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EFFECT OF PLANTING DATE AND VARIETY OF COWPEA [Vigna 
unguiculata (L.)Walp.] ON GREEN POD PRODUCTION 
 
BY 
YAKUBU EMMANUEL ANSOBA 
(10048080) 
 
 
THIS THESIS IS SUBMITTED TO THE DEPARTMENT OF CROP SCIENCE, 
UNIVERSITY OF GHANA, LEGON IN PARTIAL FULFILLMENT OF THE 
REQUIREMENTS FOR THE AWARD OF MPHIL CROP SCIENCE 
(HORTICULTURE OPTION) 
 
 
CROP SCIENCE DEPARTMENT 
COLLEGE OF AGRICULTURE AND CONSUMER SCIENCE 
FACULTY OF AGRICULTURE 
UNIVERSITY OF GHANA 
 
 
JUNE 2013 
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DECLARATION 
I declare that I designed and executed this research work hereby submitted to the Crop 
Science Department of the University of Ghana Legon, for the award of Master of 
Philosophy in Crop Science (Horticultural option), and that it has not previously been 
submitted by me for a degree at this or any other university; and that all material contained 
has been duly acknowledged. 
 
……..………………………………… 
YAKUBU EMMANUEL ANSOBA 
(Student) 
 
 
………………..………………………. 
SUPERVISOR: PROF J. C. NORMAN 
(University of Ghana, Crop Science Department) 
 
 
…………………..…………………… 
CO-SUPERVISOR: DR. R. A. L. KANTON 
(CSIR – Savanna Agricultural Research Institute) 
 
 
………………..……………………… 
DR. C. A. AMOATEY (MRS) 
(University of Ghana, Head of Department) 
 
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ABSTRACT 
A study was carried out in 2012 in a Sudan savanna ecology in Ghana aimed at identifying 
the optimal planting dates and suitable cowpea varieties for green pod production. Six 
planting dates were considered starting from the onset of the rainy season (20th June, 30th 
June, 12th July, 25th July, 2nd August and 12th August), and four improved cowpea varieties 
released by Savanna Agricultural Research Institute (SARI) of the Council for Scientific and 
Industrial Research (CSIR) as Baawutawuta, Padi-tuya, Songotra and Zaayura. The 
experimental design used was a factorial Randomised Complete Block with five replications. 
Growth and yield parameters including plant height, stem diameter, number and weight of 
leaves, number and weight of branches, pods per plant, mean pod weight, pod diameter, pod 
length, leaf area, plant canopy and fibre content of the green pods were determined. Results 
indicated that the interaction effect of planting date and varieties on plant height was not 
significant during the early ages of plants but became significant from the fifth week 
onwards. Leaf area, pod diameter and fibre content of green pods were also significantly 
affected by interaction effect between variety and planting date. Pod length, pod number per 
plant and green pod yield per plant were not influenced by the interaction effect of planting 
dates and cowpea varieties but the different varieties responded differently to the different 
planting dates. The highest mean pod number per plant and green pod yield per plant did not 
follow the same trend as Baawutawuta recorded the highest mean pod number but was not 
the highest yielder per plant; while Padi-Tuya which did not produce the highest mean pod 
number per plant was the highest yielder per plant. The improved varieties proved to be 
suitable materials for green pod production but the date of planting for higher pod yield 
varied with variety considering the fact that Baawutawuta and Padi-Tuya produced highest 
pods per plant when planted on 12th August while Songotra and Zaayura recorded their 
highest number of pods per plant when planted on June 30th. 
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DEDICATION 
 
I dedicate this work to the sweet memories of my late wife (Madam Angelina Affi-Pungu), 
and to my beloved children whose love I so much cherish. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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ACKNOWLEDGEMENT 
Thanks to the Almighty God for His divine guidance, protection and good health that has 
brought me this far in the academic laurel. 
 
I am particularly happy and express my unreserved and profound gratitude to my supervisor: 
Prof. J. C. Norman for his patience, guidance and constructive criticisms and priceless 
suggestions throughout this research work that has immensely contributed to my success. 
 
All staff and workers of the Crop Science Department of the University of Ghana Legon, 
most especially the lecturers, I appreciate you for all the assistance and knowledge imparted 
to me during the course of my studies. 
 
I am also most grateful to the Principal and staff of Methodist University College Ghana, for 
all the countless and tireless assistance given to me that has also earned me this educational 
level. May the Almighty God richly bless and promote all your Godly and academic 
activities, and carry you to endless heights. 
 
Friends and relatives advised, supported and contributed to my study and write-up; I 
acknowledge their efforts especially Patrick Apania (a friend turned brother), Simon Atombil, 
Eadbert Ansoba, Francis Kusi and Peter Asungre. 
 
Finally but not the least, I owe special words of indebtedness to Prof F. Fianu, currently at the 
Wenchi  campus of the Methodist University College Ghana and all other well-wishers who 
in diverse ways helped to make it possible for me to pursue this course.  
 
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TABLE OF CONTENTS 
DECLARATION……………………………………………………………………...……………..    i 
ABSTRACT……………………………………………………………………...………………….    ii 
DEDICATION ……………………………………………………………………...……………..    iii 
ACKNOWLEDGEMENT……………………………………………………………………...……   iv 
LIST OF TABLES……………………………………………………………………...……………  vii 
LIST OF FIGURES……………………………………………………………………...………… ..  ix 
LIST OF ABBREVIATIONS……………………………………………………………………... …x 
CHAPTER ONE……………………………………………………………………...……………..      1 
1.0 INTRODUCTION ............................................................................................................................ 1 
Objectives of the Study ........................................................................................................................... 7 
Main Objective: ...................................................................................................................................... 7 
Specific Objectives: ................................................................................................................................ 7 
CHAPTER TWO……………………………………………………………………...………………. 8 
2.0 LITERATURE REVIEW ................................................................................................................. 8 
2.1 Planting date on growth of cowpea ................................................................................................... 9 
2.2 Planting date on yield of cowpea .................................................................................................... 13 
2.3 Fibre development .......................................................................................................................... 19 
CHAPTER THREE……………………………………………………………………...…………..  21 
3.0 Materials and Methods .................................................................................................................... 21 
3.1 The Study Area and Site of Experiment ......................................................................................... 21 
3.2 Soil of the experimental area .......................................................................................................... 22 
3.3 History of land ................................................................................................................................ 24 
3.4 Materials ......................................................................................................................................... 25 
3.5 Experimental Design and Layout .................................................................................................... 25 
3.6 Land Preparation and Cultural Practices ......................................................................................... 27 
3.7 Data collected .................................................................................................................................. 29 
3.8 Data analysis ................................................................................................................................... 37 
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CHAPTER FOUR ……………..……………………………………………………………….38 
4.0 RESULTS ....................................................................................................................................... 38 
4.1 Vegetative growth ........................................................................................................................... 38 
4.2 Flowering and podding ................................................................................................................... 59 
4.3 Yield and yield components ............................................................................................................ 63 
4.4 Pod quality ...................................................................................................................................... 68 
4.5 Correlation among some parameters of the cowpea experiment .................................................... 71 
CHAPTER FIVE…..………………………………………………………………………………….73 
5.0 DISCUSSION ................................................................................................................................. 73 
5.1 Effect of Planting Date and Varieties on crop growth and yield: ................................................... 73 
CONCLUSION ………………………………………………………………………………..……...96 
RECOMMENDATIONS ……………………………………………………………………..99 
REFERENCES …….………………………………………………………………………………..100 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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LIST OF TABLES 
Table 1: Some Climatic Data of 2012 for the Period of Experimentation at Manga Station 
(Experimental Site)…………………………………………………………………………22 
Table 2: Physical and chemical properties of the soil (0 – 25cm) of the experimental area (2012) 
……………………………………………………………………………………………244 
Table 3: Effect of planting date and variety of cowpea on plant height (cm) at late vegetative stage (5 
WAS). …………………………………………………………………………………….39 
Table 4: Effect of Planting Date and Variety of Cowpea on Plant Height (cm) at Flowering (6 WAS). 
……………………………………………………………………………………………40 
Table 5: Effect of planting date and variety of cowpea on plant height (cm) at first harvest (7 WAS). 
…………………………………………………………………………………………….41 
Table 6: Effect of planting date and variety of cowpea on stem diameter (mm) at late vegetative stage 
(5 WAS). …………………………………………………………………………………42 
Table 7: Effect of planting date and variety of cowpea on stem diameter (mm) at flowering (6 WAS) 
…………………………………………………………………………………………….43 
Table 8: Effect of planting date and variety of cowpea on stem diameter (mm) at first harvest            
(7 WAS) ………………………………………………………………………………….44 
Table 9: Effect of planting date and variety of cowpea on dry stem weight (g) per plant at late 
vegetative stage (5 WAS) …………………………………………………………………45 
Table 10: Effect of planting date and variety of cowpea on dry stem weight (g) per plant at flowering 
(6 WAS) ………………………………………………………………………………….46 
Table 11: Effect of planting date and variety of cowpea on dry stem weight (g) per plant at first 
harvest (7 WAS) ………………………………………………………………………….47 
Table 12: Effect of planting date and variety of cowpea on number of leaves per plant at late 
vegetative stage (5 WAS) ……………………………………………………………….49 
Table 13: Effect of planting date and variety of cowpea on number of leaves per plant at flowering (6 
WAS) …………………………………………………………………………………….49 
Table 14: Effect of planting date and variety of cowpea on number of leaves per plant at first harvest 
(7 WAS). …………………………………………………………………………………50 
Table 15: Effect of planting date and variety of cowpea on weight (g) of dry leaves per plant at 
flowering (6 WAS). ………………………………………………………………………51 
Table 16: Effect of planting date and variety of cowpea on weight (g) of dry leaves per plant at first 
harvest (7 WAS). …………………………………………………………………………51 
Table 17: Effect of planting date and variety of cowpea on number of branches from main stem at 
flowering (6 WAS). ………………………………………………………………………52 
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Table 18: Effect of planting date and variety of cowpea on number of branches at first harvest (7 
WAS). ………………………………………………………………………………….…53 
Table 19: Effect of planting date and variety of cowpea on dry weight (g) of roots per plant at 
flowering (6 WAS). ………………………………………………………………………55 
Table 20: Effect of planting date and variety of cowpea on dry weight (g) of roots per plant at first 
harvest (7 WAS). …………………………………………………………………………56 
Table 21: Effect of planting date and variety of cowpea on dry biomass (haulm) weight (kg) per plot 
………………………………………. ……………………………………………………57 
Table 22: Effect of planting date and variety of cowpea on leaf area (cm2). ……………………58 
Table 23: Effect of planting date and variety of cowpea on canopy diameter (cm). …………………59 
Table 24: Effect of planting date and variety of cowpea on days to first flower opening …………60 
Table 25: Effect of planting date and variety of cowpea on days to 50% flowering. ………………61 
Table 26: Effect of planting date and variety of cowpea on days to first pod set. …………………62 
Table 27: Effect of planting date and variety of cowpea on days to first harvest. …………………63 
Table 28: Effect of planting date and variety of cowpea on number of pods per plant. …………64 
Table 29: Effect of planting date and variety of cowpea on weight (g) of pods per plant. …………65 
Table 30: Effect of planting date and variety of cowpea on green pods yield …………………66 
Table 31: Effect of planting date and variety of cowpea on mean pod weight (g) of green pods. ..67 
Table 32: Effect of planting date and variety of cowpea on number of seeds per pod. ………...68 
Table 33: Effect of planting date and variety of cowpea on pod length (cm). ……………………69 
Table 34: Effect of planting date and variety of cowpea on pod diameter (mm). …………………70 
Table 35: Effect of planting date and variety of cowpea on fibre content (g/100g) of green pods. ..71 
Table 36: Correlation matrix of some parameters…………………………………………………...72 
 
 
 
 
 
 
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LIST OF FIGURES 
Figure 1: Plot Size Illustration……………………………………………………………..…………27 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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LIST OF ABBREVIATIONS 
Bno.FH      Number of branches at first harvest 
DAP    Days after planting   
DFF    Days to 50% flowering 
LA                     Leaf area 
Lno.FH    Number of leaves at first harvest 
MPW     Mean pod weight 
PD    Pod diameter  
PHFH     Plant height at first harvest 
PL     Pod length 
PltCano     Plant canopy 
PPlt     Pods per plant 
SDFH    Stem diameter at first harvest 
WAS     Weeks after sowing 
Yld/Ha                  Yield per hectare 
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CHAPTER ONE 
       INTRODUCTION 
Cowpea [Vigna unguiculata (L.)Walp.] is a diploid species (2n = 2x = 22) 
belonging to the section catiang, subspecies unguiculata, genus Vigna, tribe 
Phaseoleae and the family Fabaceae (Maréchal et al., 1978). Cowpea is an annual 
legume that belongs to the family Leguminoceae and the subfamily Papilionaceae 
(Cobbley, 1976). 
 
The general classification and nomenclature of the plant has been uncertain. 
However, Sellsschop (1962) and Pursglove (1976) opined that all its cultivars 
belong to the wild cowpea, Vigna unguiculata (L) Walp which is indigenous to 
tropical Africa. Faris, (1965) also agreed that it is likely the crop was first 
domesticated in Africa and spread to Asia and the Mediterranean since the wild 
species of the crop is widely distributed in Tropical Africa. Pursglove, (1976) also 
reported that the Spaniards introduced cowpea to the West Indies and the United 
States of America. Despite all reports as above, different centres of origin of 
cowpea have been reported by various researchers as Central Africa, South 
America, Asia and Persia (Faris, 1965, Summerfield et al., 1974). Davis, (1991) 
reported of the history of cowpea dating back to ancient West African cereal 
farming, 5 to 6 thousand years ago, where it was closely associated with the 
cultivation of sorghum and pearl millet, and therefore believed to have its origin in 
Africa.  
 
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In Africa, Nigeria and Niger are predominant in cowpea production and is 
cultivated primarily for seed, but also as a vegetable (for leafy greens, green pods, 
fresh shelled green peas, and shelled dried peas), a cover crop and for fodder 
(Duke, 1983; Davis et al., 1991; Quin, 1997). Cowpea is a tropical drought 
tolerant crop that is well distributed throughout Central and West Africa, and 
Asia, but West Africa accounts for about 70% of total world production of cowpea 
(IITA, 1997). The drier savanna and the Sahelian region of West and Central 
Africa produce about 70% of cowpea’s worldwide production, with Nigeria, Niger 
and Brazil being the largest producers (Singh et al., 2002). 
 
A wide range of soil conditions supports cowpea growth but does best on well-
drained and medium fertile soils. In tropical Africa, the wild unguiculata is 
widespread, which suggest that it was domesticated here and later to other parts of 
the world (Purseglove, 1976). Johnson, (1970) also reported that in Tropical 
Africa, the cowpea crop is mostly grown in the savanna regions and the leading 
producers of cowpea include Nigeria, Benin, Burkina Faso and Niger. Cowpea is 
comparable to corn in climatic adaptation except that it requires greater heat and 
as such sensitive to frost.  
 
Though cowpea is this crop’s popular name, it has a number of common names. In 
the United States, it is called black-eyed beans, black-eyed peas or southern peas, 
whereas in India and Brazil, it is referred to as lobia and caupi, respectively. In 
French speaking countries of Africa, Niébé is the common name, but there are 
local names depending on the ethnic group, such as ‘niao’ in Senegal, ‘wakye’ in 
Nigeria and ‘luba hilu’ in the Sudan. In Ghana we have local names like ‘tuya’, 
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‘twue’, ‘teh’, ‘yor’ and ‘adua’, featuring for the same crop in Dagbani, Buili, 
Grunie, Ga, and Akan languages respectively. 
 
Cowpea is grown as a vegetable and both mono and poly-cropping are practiced 
in West Africa. Fields are located in rural areas because of cheap land and labour 
availability and the produce transported to both local and distant markets 
(Norman, 1992). Assorted meals are processed from mature cowpea pods and the 
immature pods eaten as vegetables. In especially the northern parts of Ghana, 
cowpea young leaves and shoots are eaten as spinach and that can be beneficial to 
consumers considering its rich nutritional and medicinal values. Fibre which is 
especially needed in the diet of man (Lindsay, 2010) is high in dried beans. The 
seed protein contents range from 23 to 32% of seed weight, rich in lysine and 
tryptophan, and a substantial amount of mineral and vitamins (folic acid and 
vitamin B) necessary for preventing birth defect during the pregnancy stage 
(Nielson et al., 1993; Hall et al., 2003). Cowpea is also known as containing a low 
amount of fat and high level of fibre which can prevent heart diseases by reducing 
the low-density lipoprotein (Phillips et al., 2003). In addition, cowpea 
consumption increases glucose blood more slowly because of the slowly 
digestibility of the legume starch promoting its usage for diabetic patients 
(Phillips et al., 2003). In the diets of most African families, cowpea constitutes an 
important component and also serves as a major source of cheap quality protein 
especially for smallholder rural dwellers that have little access to animal protein 
(Tanzubil, 1986). 
 
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Seeds of cowpea, leaves and green pods are used solely or in combination to 
prepare soups and stews. Various parts of cowpea are also used in the preparation 
of different meals like traditional cakes (‘kose’), ‘waakye’ (rice and beans cooked 
together), and ‘yorke-gari’ (beans served with ‘gari’ – a product of cassava). 
 
Cowpea is one of the most important grain legumes in Ghana in terms of 
production and consumption, and the second most important legume grown after 
groundnut (Tanzubil, 1986). Worldwide production of cowpeas is approximately 
20 million acres and the increasing agricultural production became an urgent issue 
since projections suggest that the global population will reach 9 billion people by 
the middle of this century (Godfray et al., 2010). According to the estimation, one 
billion people will suffer from hunger because they do not have access to food in 
terms of quantity (protein deficit) and quality (micronutrient deficit), while the 
vast majority will be living in the developing countries.  
 
For most smallholder farmers in sub-Saharan Africa cowpea is not only a source 
of income but also contributes to the sustainability of cropping systems and soil 
fertility improvement in marginal lands through the provision of ground cover and 
crop residue, suppression of weeds and fixing nitrogen (Abayomi et al., 2008). In 
West Africa, growing cowpea as a vegetable is also on part-time and in gardens as 
production is for both subsistence and for cash (Norman, 1992). Various types of 
production are practiced in Ghana as explained by Norman (1992) which includes 
truck farming, home gardening, market gardening, and dry season vegetable 
production. 
 
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Grain yields of cowpea are usually very low in Africa which range between 240 
and 300 kg/ha (Rachie, 1985). However, between 1,000 and 4,000 kilogrammes of 
grain yield per hectare are possible under optimum conditions with plants 
protected against insect pests attack. Several arthropod pests seriously reduce the 
production potential of cowpea. It is reported that post flowering insect pests 
cause economically significant grain yield losses (Jackai et al., 1985). 
 
The low productivity of cowpea is also associated with the fact that farmers still 
grow unimproved landraces because improved landraces and locally adapted 
improved cultivars are unavailable (Shiringani, 2011). Norman (1992) also 
highlighted a range of factors that limit vegetable production. Producing cowpea 
as a vegetable is certainly affected by some of such factors as climate, lack of 
capital, lack of extension services, poor cultural practices, danger of chemicals, 
transportation and lack of suitable varieties. Little or no attention is also given to 
research and development of cowpea green pod production just as is the case with 
indigenous leafy vegetables in Africa (Norman, 1992, Norman, 2003 and 
Adebooye, 2011). 
  
Eating of green pods has been a practice by Ghanaians since the introduction of 
cowpea. People, especially in the Upper East Region cook and eat fresh bean pods 
that are not dry, and also bean leaves plus young pods that have not yet been filled 
as a meal and soup respectively. These meals are prepared from only local cowpea 
varieties which take long periods to mature. Production of green pods is however 
not a common practice in the northern parts of Ghana, though one can find green 
beans being sold by some few vegetable venders. The introduction of cowpea 
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green pod production in Bawku will be of immense benefit to the population of 
not only Bawku but the Upper East Region and Ghana as a whole. The choice of 
the four varieties being evaluated is mainly due to the fact that they have recently 
been released by Savanna Agricultural Research Institute (SARI) of the Council 
for Scientific and Industrial Research (CSIR), in 2008 as also appropriate for seed 
production in the region. These early yielding cowpea varieties are well suited to 
the agro-ecological conditions of the area, which has of late been experiencing 
insufficient and erratic rainfall distribution as a result of climate change. The 
attribute of early maturity of these cowpea varieties will be beneficial to find 
reasons to produce multiples of the crops especially as green pods in the short 
rainy season that the area experience.  
 
Even though early maturing varieties have been developed to mitigate the 
maturity period yet no conscious attempt has been made to establish the 
possibility of cultivating these varieties for green pods, and also to establish 
especially the crude-fibre content of green pods. Considering the importance of 
green pods and the possibility of several croppings and harvests in one season, this 
study was undertaken to find suitable cowpea varieties and also explore their 
possible use for green pod production and appropriate planting periods for 
maximum yield.  
 
 
 
 
 
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                    1.5 Objectives of the Study 
      1.5.1 Main Objective: 
To identify the optimal planting dates and suitable cowpea varieties for green pod 
production. 
 
1.5.2 Specific Objectives: 
1. To identify suitable cowpea varieties with high green pod yield. 
2. To determine the optimal planting date for high green pod yield. 
3. To determine the fibre content of the green pods of the different cowpea varieties 
evaluated. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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CHAPTER TWO 
                     2.0 LITERATURE REVIEW 
Cowpea production in Ghana is largely dependent on rainfall. As almost every 
cowpea farmer primarily grows cowpea for seed, the crop especially the improved 
varieties, are planted late in the season sometimes after harvesting an early crop 
like early millet. In order to harvest clean seed, farmers intentionally delay 
planting so that harvesting will coincide with the end of rains thereby giving them 
a clean seed harvest. Quite often the time of planting is misjudged and yields are 
adversely affected as accurate time of planting is a key factor that influences 
production in rain-fed agriculture (Ati et al. 2002). In the Upper East region of 
Ghana, just as in many rain-fed agricultural areas of Africa, the rains start with 
light drizzles and even with intermittent dry spells making moisture a limiting 
factor for germination of seeds, emergence and possible death of young plants 
(Makarau, 1995). While rain is not adequate at the early periods of the year for 
growing some crops, most weeds grow which later compete with crops thereby 
reducing yields (Frimpong, 2002). Unlike in the Transition and Guinea Savanna 
zones of Ghana where planting starts late August and early April respectively 
(Kumaga et al. 2002), planting in Manga/Bawku which is also in the Sudan 
Savanna, is usually in June.  
 
 
 
 
 
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2.1 Effect of planting date on growth of cowpea 
2.1.1 Planting date on germination 
Shaw et al., 1994 reported that sufficient surface soil moisture was essential to 
permit early spring germination of Spiny hopsage (Gruyiu spinosa [Hook.] Moq.), 
and so it is necessary to sow in late fall or early winter. Hybrid types of sorghum 
influence seed germination as far as temperature requirement is concerned. Krieg, 
1994 reported that temperate hybrids had higher minimum temperature 
requirement than tropical adapted hybrids. Germination of cowpea could be poor 
if planted too early (Republic of South Africa National Department of Agriculture, 
1995). Slow and incomplete emergence caused by chilling damage can occur 
when sowing is done too early in soils with temperature cooler than 19oC (Ismail 
et al., 1997). Kawube et al., (2005) reported from a study that 15% salt solution 
density can be used as an alternative to seed dressing in reducing transmission of 
rice and cowpea seed-borne diseases and improving rice germination and yield in 
the field. Storage materials influence the viability of seed as determined by its 
germination percentage while varietal influences occur on the germination 
percentage of cowpea (Ihejirika, 2007). Cowpea varieties were evaluated in a rain 
forest environment to determine the physiological qualities of cowpea seeds 
produced, and reported that variety and location had significant effects on 
germination percent, germination rate index and seedling length. The study further 
deduced that high quality seeds of cowpea can be produced in transition 
environments (Olasoji et al., 2013). 
 
 
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2.1.2 Planting date on seedling establishment  
Factors that affect seedling emergence rate and establishment include planting 
depth, soil temperature and available soil water content. A key factor that also 
contributes to better sorghum stand establishment is hybrid selection. Selected 
genotypes must be tolerant to low temperatures during seed germination, seedling 
emergence, and early plant growth if early planting is to be practiced (Keim and 
Garden, 1984). It has been reported that when planting of corn is delayed until soil 
conditions are nearer the optimum for early plant growth and development, it is a 
plus to management strategies useful in overcoming early plant development 
problems (Herbek et al., 1986). Available and sufficient rainfall has an influence 
on seedling establishment of cowpea which can contribute to maximum seed yield 
(Republic of South Africa National Department of Agriculture, 1995). Emergence 
rate of sorghum may be affected by unfavourable soil environment if planting is 
done early and that can produce poor establishment of the crop (Heiniger et al., 
1997).  
 
2.1.3 Planting date on stem diameter 
Peduncle thickness of pineapple was not significantly affected by planting date 
(Norman, 1981). Congo jute planted late produced small basal diameter when 
planted in Ghana which also led to low yield of dry fibre (Amankwatia, 1979). 
Relatively big stalks were produced when roselle (Hibiscus sabdariffa L.) was 
grown early in Ghana (Amankwatia, 1992).  
 
 
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     2.1.4 Planting date on plant height 
Delayed planting can reduce dry weight, leaf area, plant height and number of 
internodes of soyabeans (Adjei-Twum, 1978). Apart from the yield of okra being 
significantly affected by planting date, the first sowing date also produced highest 
plant height when three planting dates (17th March, 2nd April, and 17th April) were 
evaluated (Sayeed, 1988). Shorter plants of Congo jute were also produced with 
late planting which also contributed to low dry fibre yield (Amankwatia, 1979). In 
a study of roselle (Hibiscus sabdariffa L.) involving sowing date in Ghana, it was 
reported that roselle produced relatively tall plants (Amankwatia and Asante, 
1992). Babatunde et al. (2002) reported of highly significant effects of sowing 
dates, intra-row spacing and the use of nitrogen fertilizers on plant height in 
roselle production. Okra planted early produced higher plant height and fruit 
length than late planted okra (Yadev, 1999; Incalcaterra et al., 2000). Obadoni, 
(2009) observed that plant height of cowpea was not significantly influenced by 
weed densities between 3 and 9 weeks inclusive. Time of first harvest of roselle in 
the Guinea savanna agro-ecological zone of Ghana had significant effect on plant 
height of the crop (Osei-Kwateng et al, 2012). 
 
     2.1.5 Planting date on flowering 
Early flowering of cowpea cultivars has been reported to lead to drought escape 
and production of high yields at some locations and in some years (Ismail et al., 
1997). Good flowering for maximum seed yield of cowpea is achieved with the 
availability of sufficient rainfall and planting cowpea too early in the season could 
also cause abscission of flowers during flowering (Republic of South Africa 
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National Department of Agriculture, 1995). Norman, (1981) reported that planting 
date did not significantly affect flowering and fruit maturity of pineapple. Yama, 
(2006) found significant differences in flowering among cowpea varieties. 
Planting dates did not influence floral initiation and opening in egg-plants when 
planted in both main and minor seasons (Nsowah, 1970).  
 
In terms of number of days to 50% flowering, there were significant differences 
among cowpea varieties studied under different weed densities (Obadoni, 2009). 
In a study in New York, when planting was done in December and January which 
was supposed to be the onset of flowering, it was reported that fewer numbers of 
days to 50% flowering of beans was recorded in one location that was noted to 
have high temperature (Wallace et al., 1995). 
 
Genotype adaptation is influenced also by a crop’s flowering period, and this 
period is a key phase in the development of crop as it is vulnerable to 
environmental stress. It is therefore the timing of this developmental stage that is 
responsible for determining a crop’s maturity and subsequent harvest 
(Summerfield, 1980). Wilson and Robinson (1995) reported that a crop’s climatic 
adaptation and yield is influenced by the period it flowers and the duration of its 
growth. Wien and Summerfield, (1984) noted that species of various crops have 
adaptive features that contribute to timely flowering. 
 
 
 
 
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     2.2 Planting date on yield of cowpea 
     2.2.1 Planting date on fruiting and pod filling 
Three planting dates (17th March, 2nd April, and 17th April) were evaluated in an 
okra crop and it was found that the first sowing date produced the highest green 
fruits (Sayeed, 1988). It has been reported that good pod filling stages for 
maximum seed yield of cowpea is also achieved with sufficient and available 
rainfall (Republic of South Africa National Department of Agriculture, 1995). 
Yadev, (1999) and Incalcaterra et al., (2000) both reported of higher number of 
fruits per plant of okra planted early, than late planted okra. Nsowah, (1970) 
reported that planting date of egg-plant varieties did not significantly influence 
fruit maturity but number of fruits and fruit weight were higher in the main season 
than in the minor season. Weight of first mature fruit, number of fruits and fruit 
weight decreased considerably with late sowings. Adcock and Lawes, (1976) 
reported that in Vicia faba L., it is possible to find two or three pods per peduncle 
but most often four or more pods are carried on a single peduncle. 
 
     2.2.2 Planting date on yield and yield components of cowpea 
One of the important cultural practices that can result in significant differences in 
the growth and yield of grain legumes is planting date (Republic of South Africa 
National Department of Agriculture, 1995). It is also reported that the type of 
cultivars planted have an influence on their optimum planting date. Good seedling 
establishment, flowering and pod filling stages for maximum seed yield of cowpea 
are achieved with the availability of sufficient rainfall. Though planting of cowpea 
can be done at the beginning of the rainy season, planting too early could make 
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germination poor and also cause abscission of flowers during flowering while on 
the other hand, planting too late may reduce yields that may be caused by early 
frost or lack of enough time for pod production (Republic of South Africa 
National Department of Agriculture, 1995). 
 
High yields of cowpea can be achieved in some locations and years when drought 
is escaped by cowpea cultivars that begin to flower early (Ismail et al., 1997). A 
report by Doku and Karikari (1970) indicates that high rains reduce seed yield of 
Bambara groundnuts. Except that leaf senescence was significantly delayed, yield 
components and yield of snap beans (Phaseolus vulgaris) were enhanced with the 
application of a growth hormone, Accel (Emongor, 2008).  
 
Peksen, (2002) reported that sowing dates on individual pod weight was not 
significant, but there were significant differences between cowpea genotypes in 
terms of pod characteristics. However, green pod yield per plant was influenced 
by sowing dates and cowpea genotypes with planting in April and May giving the 
highest green pod yield per plant. 
 
Early maturing varieties of soyabeans were advantageous in yield over late 
maturing varieties, but the result was not dependent on planting date (May et al., 
1989).  High grain yield of cowpea can be achieved with early sowing if also the 
early sowing leads to escape of the hot weather conditions that hinder 
reproductive development (Marfo and Hall, 1992). A report highlighted that 
delayed planting of early maturing cultivars of cowpea substantially delayed 
maturity and that eliminated the advantage of early harvest of the early planted 
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and early maturing cowpea cultivars (Fatokun et al., 2002). Significant differences 
between varieties of egg-plant were observed on growth characters in two planting 
dates. However, planting dates did not influence floral initiation, floral opening 
and fruit maturity but number of fruits and fruit weight were higher in the main 
season than in the minor season. In later sowings in two different years, weight of 
first mature fruit, number of fruits and fruit weight reduced considerably within 
each season (Nsowah, 1970). 
 
Plant growth and yield are influenced by planting date as a result of differences in 
air temperature, radiation and available soil moisture which occur at different 
growth stages. These factors could also interact with different dates of sowing on 
the development of plants (Osafo, 1975). Nafziger, (1994) reported that crop 
yields fast declined when planting date of crops is advanced or planting is done 
beyond optimum planting date. Vegetative growth of maize far exceeds ear and 
grain yield when planted late as compared with early planted maize that produce 
high ear and grain yield (Free et al., 1966; Pendleton, 1969). Best yields of maize 
were obtained when planted mid-March in the forest zones of Ghana and planting 
late- May to mid-June gave best yields in the Guinea savanna zone, while best 
yields were obtained in the coastal savanna zone when maize was planted in the 
2nd – 3rd week in April (Koli, 1970). Crop yield losses between 40 – 55% can 
occur when planting is done 2 weeks earlier or later than the optimum planting 
date. September to November has been adjudged the period of optimum growing 
condition for maize in the minor season of the coastal savanna (Wills, 1962). 
Early planting of maize in the minor season of the coastal savanna region of 
Ghana especially planting under irrigated conditions contribute to high or 
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increased grain yield than yields of the major season (Leyenaar and Hunter, 1978). 
These increased yields were attributed to the availability and intense solar 
radiation since that is very vital in the plants’ photosynthetic processes. It has been 
found that planting date did not significantly affect the growth and yield of sweet 
corn (Norman, 2002). A confirmed report by Laner et al., (1999) has it that 
highest grain yields of corn are got with early sowing but delays over two weeks 
in sowing recorded declining yields at a rate of between 0.2 to 1.7%. Early 
planting gives maximum grain yield as better weather conditions are met while 
planting in the later parts of the growing season bring about gradual losses in 
potential grain yield of maize (Shioga, 2010). 
 
Fruit yield performance was highest with okra planted between March and April 
than with planting between October and January (Kamalanathan et al., 1970). 
Okra responded positively to sowing date and plant spacing highlighting that 
earliest sowing (25th May) produced highest average yield generally and that 
yields decreased with each sowing date until 5th November sowing (Gupta et al., 
1981). Apart from the yield of okra being significantly affected by planting date, 
the first sowing date produced highest green fruit, plant height and number of 
leaves per plant when three planting dates (17th March, 2nd April, and 17th April) 
were evaluated (Sayeed, 1988). Iremiren and Akly, (1986) observed vigorous 
plant growth of okra, number of pods per plant and pod yield was highest with 
early sowing (1st April) as compared to late planting (1st June). A report by Singh 
et al., (1986) has it that seed yields of okra was highest in plots planted first (15th 
June). Plant height, number of fruits per plant, and fruit length of okra planted in 
June was higher and above okra planted 12th August (Yadev, 1999). The findings 
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of Incalcaterra et al., 2000 was not too different when they reported that plant 
height, number of pods and yield of okra were highest in the first sowing date than 
in the second sowing date (1st and 15th April respectively). 
 
In Ghana, Congo jute planted late produced shorter plants, small basal diameter, 
low fresh stalk yield, less retted fibre and consequently low yield of dry fibre 
(Amankwatia, 1979). Relatively tall plants, big stalks, short vegetative period and 
short flowering time were some of the findings of Amankwatia, 1992 when roselle 
(Hibiscus sabdariffa L.) was grown in Ghana.  Sweet potatoes produce highest 
tuber yields including component values when planted early while lower yields 
are recorded when planted late (Singh, 1992). 
 
An experiment conducted in South Africa registered results of seed yield of 
cowpea that revealed that there was highly significant interaction among planting 
dates, genotypes and locations (Shiringani, 2011). Year sown, sowing date, and 
season influenced the first harvesting date and yield in both pole and dwarf bean 
varieties (Saglam, 2000). Significant differences were also observed among 
varieties while interaction between season and sowing date in both pole and dwarf 
bean varieties, and also interaction between season and year in pole bean varieties 
significantly affected the yield of beans. In three seasons, cowpeas infested with 
scab were sown on different dates. Results revealed higher scab incidences when 
cowpea was sown early and also yield and yield components of this early sown 
cowpea were lower than those from late sown crops. Poor quality grain with 
plenty of shriveling was realised in the early sown crops when compared with the 
late sown crops (Mbong, 2010). In a first season (April – June 1976) four bean 
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genotypes were planted on three planting dates while four planting dates involving 
the four genotypes were carried out in a second season (Nov. 1976 – Jan. 1977). 
Generally there was yield decline with delayed sowing in the two seasons though 
in the second season yields were lower with the first planting. Also in the second 
season yields declined less rapidly (Fisher, 1980). 
 
Fatokun et al., (2002) reported that the advantage of early harvest of early planted 
early maturing cultivars of cowpea was eliminated when delayed planting of early 
maturing cultivars substantially delayed maturity. Planting cowpea early (April 
and May) was superior to planting in June and July as seeds with better hydration 
properties were produced. Better light reception, dry matter accumulation and 
more cells contributed to this result (Ibeawuchi, 2004). Cowpea seeds with lower 
water imbibition percentage and seed protein content were produced when 
harvested mature green whereas seeds with higher water imbibition percentage 
and seed protein content were produced when harvested dry. 
 
Obadoni, (2009) found that number of pods of cowpea and consequently yield 
was significantly influenced by varying weed densities and varieties.The yield 
potential of a crop is strongly influenced by its period of flowering and growth 
duration and therefore factors such as planting date and site are of immense 
importance since they contribute to the development and subsequent responsibility 
for variability in yield and yield components (Wilson and Robinson (1995).  
 
A report by Schou et al. (1978) has it that yield is influenced greatly by changes 
that occur during flowering to physiological maturity as compared with the period 
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from emergence to flowering. While Moot, (1993) in his report suggested that the 
variability in yield of grain legumes is correlated with changes in seed number, 
other scientists reported that yield components have been used widely to explain 
variations in the yield of grain legumes such as Vicia faba, Phaseolus vulgaris, 
Cicer arietinum,and Pisum sativum (Husain et al., (1988), Dapaah et al., (2000), 
Verghis (1996) and Nicholas et al. (1985) respectively. Dhital et al. (1998) 
reported of planting dates influencing both yield and yield components of cowpea 
highlighting that early planting produced both the highest number of pods per 
plant, number of seeds per pod and subsequently seed yield per hectare as 
compared with late planting which produced the lowest number of pods per plant, 
seeds per pod and seed yield per hectare respectively. 
 
In studies on planting cotton in Ghana, it was reported that planting early (late 
May to June) in the season produced significantly higher yields than planting later 
in the season (after early July) for northern Ghana, while in the southern parts, 
significantly higher yields was recorded when cotton was planted July to August 
than planting later in September. June to early July and August to early September 
planting of cotton in the north and south respectively was best for higher yields as 
pests are escaped and with sufficient moisture for growth (Koli,1973). 
 
     2.3 Fibre development 
In a study conducted to examine the influence of mutation induction on nutritional 
quality of cowpea involving two plant types of cowpea; ‘IT84S 2246 D’ mutants 
and the non-irradiated parent, results showed non-significant variation between 
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the plant types for  crude fibre content (Olabisi, 2007). Improved and local 
varieties of cowpea both contribute significant amounts of micro and macro 
nutrients with other plant parts like leaves having greater mineral content than the 
grains; and therefore consumption of the leaves alongside the grains would be of 
nutritional advantage and should be promoted in addition to encouraging farmers 
to plant the higher yielding cowpea varieties and preferred local varieties 
(Mamiro, 2011). Low fibre (0.5% - 0.7%) was one of the findings when 
Akpapunam, (1995) studied the effects of traditional lactic acid fermentation and 
the addition of malt on the physicochemical properties of maize-cowpea blends. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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CHAPTER THREE 
                  3.0 Materials and Methods 
       3.1 The Study Area and Experimental Site 
The study was carried out at the sub-Station of the Council for Scientific and 
Industrial Research (CSIR) – Savanna Agricultural Research Institute (SARI) at 
Manga near Bawku. The station is about 4 kilometres off the Bolgatanga – Bawku 
highway southwards on entering Bawku township and lies between latitude 11o 
01’ N, and longitude 00o 16’W, and has an altitude of 249 metres above sea level. 
Manga is in the Sudan-Savanna agroecology in northern Ghana. The vegetation is 
predominantly Sudan savanna, which consists of short grasses and a few and 
widely spaced trees and shrubs that have fire resistance as a characteristic (Atta-
Quayson, 1985). 
 
Environmental factors are the main factors that crop growth depend on and 
therefore influence the yielding potential of the crops. Bawku has a climate that is 
characterized by a mono-modal rainfall starting in June and stops at the end of 
September but in exceptionally wet seasons it extends into part of October. The 
rest of months are usually hot and dry. The average annual rainfall is less than 
1000 mm and is erratic in distribution, and for the year 2012 a total rainfall of 
1030.3 mm was recorded at the Manga meteorology station; showing that the 
season was an exceptional one (Table 1). In the past the rains normally started in 
May, but in recent years the rains start in June. The total rainfall received within 
the cropping season only (June to September), was 842.5 mm. Table 1 also shows 
that the mean monthly minimum air temperature ranged from 22.6oC (July) to 
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30.2oC (September) while the maximum temperature ranged from 30.5oC 
(August) to 32.8oC (June). The lowest mean relative humidity was recorded 
during the month of June (68.3%) and the highest in September (93.2%). 
 
Table 1: Some Climatic Data of 2012 for the Period of Experimentation at 
Manga Station (Experimental Site). 
Month Total Rainfall     Mean Temperature      Mean Relative Humidity 
(mm) (oC) (%) 
   Minimum Maximum    Minimum Maximum 
June 147.6 23.2 32.8 68.3 88.5 
July 256.3 22.6 31.5 74.8 91.6 
August 214.8 22.9 30.5 78.6 92.6 
September 223.8 30.2 31.4 72.1 93.2 
Source: Meteorological unit of CSIR – SARI at Manga sub-Station 
 
    3.2 Soil of the experimental area 
The soils of the Manga sub-Station of the Council for Scientific and Industrial 
Research – Savanna Agricultural Research Institute (CSIR – SARI) though has 
been mentioned as comprising of three soil series (ie Verempere series that 
occupy the upper part of the station, Tafali series occupying the middle part and 
Berenyasi series occupies the lower or valley of the station), is generally classified 
only as Verempere series (Obeng, 2000, and Affipungu, 2005).  This subgroup of 
soils is a product of weathered granite and found to be deep to very deep, red and 
brown, and mostly sandy soils. The particular field that was used was a flat land 
and according to soil classification by FAO-UNESCO (1988) the soil is Plinthic 
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Lixisol and developed from granite. The soil is well drained and moderately deep, 
and the texture of it is light to medium that also qualifies it as sandy-loam (Anane, 
2005). Using an auger, a bulk soil sample was taken from a depth of 0 – 25cm 
before sowing for analysis in the Soils Chemistry laboratory of Savanna 
Agricultural Research Institute, at Nyankpala and some physical and chemical 
properties are presented in Table 2 below. Soil was taken diagonally from both 
diagonals at approximately 10 metre intervals and put together, mixed thoroughly 
and a part of it taken for the analysis. The results revealed that the soil of the 
experimental area is mainly sandy and acidic. All other plant growth requirements 
in the soil are below average except the levels of potassium which is moderate 
(Table 2). 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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       Table 2: Physical and chemical properties of the soil surface (0 – 25) of the 
                                   experimental plot (2012) 
 
Soil Properties Experimental Plot at Manga – Bawku 
FAO-UNESCO Soil Classification Plinthic Lixisol 
Sand (%) 84.56 
Silt (%) 12 
Clay (%) 3.44 
Soil Texture Loamy sand 
Soil pH (CaCl2) 4.26 
Organic Carbon (%) 0.35 
Total Nitrogen (%) 0.06 
Available P (mg kg-1 7.77 
Exchangeable Cations cmol (+) kg-1  
Ca 0.80 
Mg 0.30 
K 33.20 
CEC [cmol (+) kg-1] 2.93 
 
Agriculture is one of the main occupations of the people in the Bawku 
Municipality and crops cultivated include maize, sorghum, sweet potatoes, 
groundnut, cowpea, and a variety of vegetables. In the field of animal production, 
almost every household traditionally rears poultry and keeps few animals like 
goats, sheep, cattle, donkeys and pigs.  
 
     3.3 History of land 
For the past three years the entire field has been put under pearl millet and maize 
production. From 2003 to 2008 the field was cropped interchangeably with maize 
and cowpea in alternate years.  
      
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     3.4 Materials 
Four cowpea varieties; IT 95 K 193 – 2, IT 97 K – 499 – 35, SARC 3 – 122 – 2, 
and SARC 4 – 75 given the names Baawutawuta, Padi-Tuya, Songotra and 
Zaayura respectively which were released by Council for Scientific and Industrial 
Research – Savanna Agricultural Research Institute (CSIR – SARI, 2008) and 
have been recommended for mass cultivation in northern Ghana were used. 
Baawutawuta (IT 95 K 193 – 2) and Songotra (IT 97 K – 499 – 35) are two best 
selections from advanced breeding lines obtained from the International Institute 
of Tropical Agriculture (IITA), Nigeria. Padi-Tuya (SARC 3 – 122 – 2) and 
Zaayura (SARC 4 – 75) were developed from exotic material derived from the 
University of Riverside, California, USA and crosses among genotypes already 
available within the Savanna Agricultural Research Institute’s germplasm. 
 
Six (6) planting dates were involved in the experiment with the first planting done 
when there was sufficient moisture for seeds to germinate. The planting dates 
were 20th June, 30th June, 12th July, 25th July, 2nd August, and 12th August of 2012. 
 
      3.5 Experimental Design and Layout 
The experiment was laid as a factorial experiment comprising the four varieties of 
cowpea and the six planting dates using a Randomized Complete Block Design 
with five replications. The factors were Six Planting dates (20th June, 30th June, 
12th July, 25th July, 2nd August, and 12th August) as one factor, and the Four 
varieties of Cowpea (Baawutawuta, Songotra, Padi-Tuya and Zaayura) constitute 
the second factor. 
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Plot size was 5m long and 5.4m wide (5m x 5.4m) = 27m2. 
Spacing used was 60cm between rows giving a total of 9 rows, and 20cm between 
plants giving a total of 25 plant–hills per row or 225 plant–hills per plot. 
 
A net plot area of 7.2 m2 was considered for harvest. Four metres long, cutting off 
½ metre each at beginning and end of rows, of the 2nd, 3rd, and 4th rows constituted 
this net plot area (Figure 1). Three other rows; the 6th, 7th, and 8th rows were those 
that were used for destructive sampling records. The three rows left (i.e. 1st, 5th, 
and 9th rows) served as guard rows. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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       Figure 1: Plot Size Illustration 
        ←0.6m ↑ 
→ 
 0.5m 
↓ 
         ↑ 
  
  
 4.0m 
  
  
↓ 
         ↑ 
 0.5m 
↓  
Row1   Row 2   Row 3 Row 4  Row 5  Row 6   Row 7  Row 8   Row 9 
 
     3.6 Land Preparation and Cultural Practices 
Land was not ploughed but harrowed with a tractor and after lining and pegging, 
ridges were made using bullocks. In order to have straight ridges, two straight 
lines along the length linking the ends of the field were ruled with the help of a 
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garden line to create paths that the bullocks first followed to make the ridges. The 
experiment was laid out and labeled on 15 June 2012; ready for the first planting 
with the next rain. 
 
Three seeds per hill were planted and thinned to one plant two weeks after 
planting.  To ensure the field was free from weeds, one manual weeding was done 
two weeks after planting. Bullocks were used to reshape the ridges at the end of 
the third week after planting which also controlled weeds. A third manual weed 
control was done in the fifth week and thereafter, hand–pulling of big weeds was 
carried out as and when necessary. 
 
Insect pests that are a problem to cowpea production in Ghana like leafhoppers, 
leaf miners, Aphid spp, Thrips spp, Mylabris sp, and pod sucking bugs (Agyen-
Sampong, 1978) were controlled by spraying plants weekly with Lamda 
cyhalothrin at a rate of 60ml per 15 litre knapsack, starting from 2nd week after 
planting and stopped after the 6th week. 
 
 
 
 
 
 
 
 
 
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     3.7 Data collected 
      3.7.1 Growth Parameters: 
      3.7.1.1 Plant Stand 
Three weeks after planting all plants were counted in the three middle rows. 
 
3.7.1.2 Plant Height 
Heights of 10 plants in each plot, that were randomly selected, were taken and 
average plant heights per plot recorded from four weeks after planting and at 
weekly intervals for four times. The periods involved were: at early vegetative 
stage {28 days after planting (DAP)}, late vegetative stage {35 days after planting 
(DAP)}, at flowering {42 days after planting (DAP)} and at first harvest {49 days 
after planting (DAP)}. Plant height was taken using a graduated measuring pole in 
centimetres (cm). The heights of the 10 plants were taken from the base of the 
plant to the terminal bud of the main stem and the average recorded. 
 
      3.7.1.3 Number of leaves per plant  
Leaf number per plant was taken at early vegetative stage (28 DAP), late 
vegetative stage (35 DAP), at flowering ({42 DAP) and at first harvest (49 DAP). 
10 plants in each plot were hand pulled (destructive sampling) and leaves 
detached from them. The average number of leaves per plant was recorded after 
counting all the leaves.  
 
 
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      3.7.1.4 Fresh and dry leaves weight per plant 
After recording leaf number from weekly destructive samplings of plants at early 
vegetative stage (28 DAP), late vegetative stage (35 DAP), at flowering (42 DAP) 
and at first harvest (49 DAP), fresh weights were taken in the laboratory with a 
sensitive electronic scale. Small-sized electronic ovens in the laboratory were used 
to dry materials that needed to be dried. Due to the fact that ovens available were 
small in size, sub-samples of the leaves were taken and their weights recorded and 
then dried in an electronic oven at a temperature of 70oC for 30 hours (by which 
period leaves were very dry) and their dry weights recorded. From the dry weights 
of samples taken, dry weight of the leaves per plant was determined by 
proportion. 
 
     3.7.1.5 Fresh and dry stem weight per plant 
The fresh stem weight of the 10 plants that were used for determining leaf fresh 
weight was used to determine mean fresh stem weight. Dry stem weight per plant 
was determined after known weights of samples of the stems were oven-dried at 
70oC for 48 hours (by which time the stems were fully dry) and extrapolated. The 
stems were not chopped into pieces but folded and placed on an electronic scale 
and their weights determined. To dry samples that were taken for that purpose, the 
samples were put in large-sized brown envelopes before putting them into the 
electronic oven. After drying, the samples were removed and immediately 
weighed and the dry stem weight per plant was determined by first converting the 
result to reflect that for the 10 stems, and then their average calculated and 
recorded.   
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      3.7.1.6 Fresh and dry root weight per plant 
The roots from the 10 plants destructively sampled at the four ages of the plant 
growth were cut and the fresh root weight per plant determined by weighing them 
in the laboratory with a sensitive electronic scale and finding their average which 
was recorded as fresh root weight per plant. Known weights of sampled roots 
were oven-dried at 70oC for 48 hours (by which period roots were fully dry) in the 
laboratory with an electronic oven and their dry weight per plant determined. 
 
     3.7.1.7 Leaf Area 
In every plot, the length and width of two leaves each from mid-height of five 
plants were measured with a ruler graduated in centimetres at 50 DAP giving a 
total of 10 leaves per plot at each measurement. The length was measured 
following the mid-rib starting from the attachment of the leaf to the petiole 
through to the end of the mid-rib per leaf. Leaf width was measured at the 
broadest part of the leaf. Their areas were then calculated by multiplying their 
lengths by their widths and also multiplied by 0.75 (Agueguia, 1999; Adeoye, et 
al., 2011). Average leaf area was recorded in centimetres. 
 
Calculation 
Leaf area was determined by the formula: 
Leaf area (LA) = Laminal length x Maximum width x 0.75 
 
 
 
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3.7.1.8 Days to first flower appearance:  
Following daily field observations, the number of days from planting to the day 
the first flower bud opened was recorded in each plot. 
 
 3.7.1.9 Days to 50% flowering  
By visual observation, the number of days from planting to the day that 
approximately 50% of plants were carrying open-flower buds was recorded per 
plot. 
 
      3.7.1.10 Days to first pod set  
The number of days from planting to first pod initiation in each plot was recorded 
as days to first pod set. 
 
      3.7.1.11 Days to first harvest  
This was taken as the number of days from planting to the day that green pods 
were first harvested in each plot. 
 
      3.7.1.12 Number of branches from main stem per plant  
The number of branches on the main stem per plant was counted from four weeks 
after planting at weekly intervals for four weeks. The periods involved were: at 
early vegetative stage (28 DAP), late vegetative stage (35 DAP), at flowering (42 
DAP) and at first harvest (49 DAP). The total number of branches from the main 
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stems of the 10 plants used in determining leaf number, weights of both leaves 
and stems, were counted and averages recorded as number of branches per plant. 
   
      3.7.1.13 Stem diameter  
Stem diameter was taken starting from early vegetative stage (28 DAP; the 
diameters of 10 plants randomly selected in each plot were recorded weekly using 
a digital caliper in millimetres. This was done at weekly intervals for 4 times (at 
early vegetative stage (28 DAP DAP), late vegetative stage (35 DAP), at 
flowering (42 DAP) and at first harvest (49 DAP). Their averages were calculated 
and recorded as stem diameter. All stem measurements on selected plants were 
taken at approximately five centimetres (5cm) above ground level. 
 
      3.7.1.14 Plant canopy diameter per plant  
In the absence of a leaf canopy analyzer, manual canopy diameter measurements 
using a measuring tape were taken at the top of 5 plants per plot. Four different 
measurements were taken on each plant and their averages recorded as plant 
canopy diameter for each of the five plants per plot. The average canopy diameter 
of the five plants from each plot were then computed and recorded as the canopy 
diameter per plant. 
 
 
 
 
 
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     3.7.2 Yield Parameters: 
      3.7.2.1 Pod number per plot  
The total number of green pods harvested in each plot was recorded at the 
growing end of plants. This is when plants have especially reached their 
maximum life spans and that, not only do they not flower and form pods again but 
are senescing. Pods in each plot were harvested at different periods when they 
were matured (green pod stage); so all green pods harvested at the different times 
were added together and recorded as the number of pods per plot. 
 
     3.7.2.2 Pod weight per plot  
The overall weight in kilograms of all green pods harvested in each plot was 
recorded as the pod weight per plot. This was arrived at by adding up all the 
various harvest weights taken with a sensitive electronic scale in the laboratory at 
the different times harvested. 
      
      3.7.2.3 Pod length 
10 randomly selected green pods from each harvest were measured individually 
with a ruler and their average length taken as pod length per plot in centimetres. 
These measurements were done in the laboratory. 
 
 
 
 
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     3.7.2.4 Pod diameter  
An average pod diameter was recorded after 10 pods per plot were randomly 
harvested and their diameter measured with a digital caliper in the laboratory and 
recorded. Measurements were taken from approximately mid-length of each pod. 
 
3.7.2.5 Number of seeds per pod  
Total seed grooves were counted from the 10 randomly selected pods for pod 
length and diameter records, and their average number recorded as the number of 
seeds per pod that probably would have been formed if left to grow to full 
maturity. 
 
3.7.2.6 Number of pods per plant 
The total number of green pods harvested from five randomly selected plants was 
obtained and the average calculated to arrive at the number of green pods per 
plant. 
 
3.7.2.7 Pod weight per plant at harvest 
The total weight of pods harvested from five plants determined. The average of 
the result obtained from the five plants was recorded as weight of pods per plant 
in grammes. 
   
 
 
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3.7.2.8 Pod yield per hectare 
The green pod yield per hectare was recorded using the following formula: Pod 
yield per plant in grams x plant population of 83,333 plants per hectare (that is 
when one plant is maintained at a spacing of 20cm x 60cm), and the result 
converted into tons. 
 
3.7.3 Fibre content of green pods 
Green pods were harvested at a developmental stage that though pods were almost 
fully developed, seeds were not fully developed, and also when pods could snap. 
Samples of these green pods were sent to Food Research Institute in Accra and 
analysed in their Chemistry Laboratory for the crude fibre content of the pods. 
The procedure used involved Pearson’s method of food analysis (Ronald et al., 
1991). 3g of each sample was stirred in petroleum spirit, settled and decanted 3 
times. Air-dried extracted samples were put in 1000 ml conical flasks and 200 mls 
0.255 N sulphuric acid measured at ordinary temperature added. These were 
gently boiled for 30 minutes while rotating flasks every few minutes in order to 
mix contents and removing particles from the sides. After the 30 minute boiling, 
the acid mixture was allowed to stand for approximately one minute and then 
poured into a shallow layer of hot water through a prepared paper-funnel, which 
was completed in 10 minutes. The insoluble matter was washed with boiling water 
until free from acid, then washed back into the original flasks by using wash 
bottles containing 200ml 0.313N sodium hydroxide solution. These collections 
were boiled again and cooled for one minute and then filtered immediately 
through a suitable filter paper. These insoluble materials were again transferred to 
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the filter paper by means of boiling water, washed first with boiling water and 
then with 1% hydrochloric acid and finally with boiling water until they were free 
from acid. Samples were then washed two times with alcohol and 3 times with 
ether. The insoluble samples were dried on an ash-less filter paper of known 
weight at 100oC to a constant weight. Finally the papers and contents were 
incinerated to ash and weighed; the weights of the ash were then subtracted from 
the increase of weight on the paper due to the insoluble material and the result is 
the fibre contained. 
 
3.8 Data analysis 
Statistical analysis of the data was done by the Analysis of Variance (ANOVA) 
using Excel 2010 and GenStat 2011 programme packages and where differences 
were significant, means were separated at the 5% using the Fisher’s Least 
Significant Difference (LSD = 0.05) test procedure. 
 
       3.9 Correlation matrix 
To establish possible relationship among parameters observed, correlation 
analysis was carried out. Plant height at first harvest (PHFH), stem diameter at 
first harvest (SDFH), number of leaves at first harvest (Lno.FH), number of 
branches at first harvest (Bno.FH), days to 50% flowering (DFF), pods per plant 
(PPlt), mean pod weight (MPW), leaf area (LA),plant canopy (PltCano), pod 
diameter (PD), pod length (PL) and yield of green pods per hectare (Yld/Ha) were 
the parameters involved in the relationship analysis. 
 
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CHAPTER FOUR 
      4.0 RESULTS 
      4.1 Vegetative growth 
      4.1.1 Plant height 
There were significant interactions between planting date and variety for plant 
heights at late vegetative stage (35 DAP), flowering (42 DAP) and first harvest 
(49 DAP). At late vegetative stage, Padi-Tuya produced significantly taller plants 
compared to the other three varieties (Table 3). Baawutawuta produced the 
shortest plants. At all the three growth stages, planting on the fourth date (25th 
July) produced the tallest plants except for Baawutawuta which produced its 
tallest plants when planted on 12th August. Second highest plant heights were 
obtained at the sixth planting date (12th August), which is especially true for Padi-
Tuya, Songotra, and Zaayura but Baawutawuta differed again from this trend by 
producing its second tallest plants when planted on the fifth date (2nd August). For 
both Baawutawuta and Songotra, shortest plants were produced with the second 
planting date (30th June). Padi-Tuya registered its shortest plant height with the 
first planting (20th June) while that of Zaayura was with the fifth planting date (2nd 
August). 
 
Padi-Tuya produced plants that were significantly different in height from 
Baawutawuta, Songotra and Zaayura at flowering (Table 4). For Padi-Tuya, tallest 
plants were produced with the planting on 25th July and the shortest when planted 
on 20th June. Plant heights of Padi-Tuya, Songotra and Zaayura showed similar 
trend with planting date as tallest plants of each variety was found with plantings 
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of 25th July followed closely by plantings on 12th August . Though Baawutawuta 
did not follow the exact order as the earlier varieties, its fourth planting (25th July) 
produced its tallest plants but this time followed by its first planting of 20th June 
(Table 4).  
 
Table 3: Effect of planting date and variety of cowpea on plant height (cm) at 
         late vegetative stage (35 DAP). 
 
 Planting Dates  
Varieties 20th June 30th June 12th July 25th July 2nd August 12th August Mean 
Baawutawuta 13.80 13.04 13.96 14.56 14.60 14.68 14.11 
Padi-Tuya 17.64 21.64 26.16 41.40 23.02 28.40 26.38 
Songotra 15.48 15.30 16.70 20.36 15.88 19.56 17.21 
Zaayura 17.76 18.28 19.24 23.32 16.22 21.28 19.35 
Mean 16.17 17.07 19.02 24.91 17.43 20.98  
Lsd (P=0.05): Planting date = 3.03, variety = 2.47, planting date x variety = 6.06 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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Table 4: Effect of planting date and variety of cowpea on plant height (cm) 
         at flowering (42 DAP). 
 
 Planting Dates  
Varieties 20th June 30th June 12th July 25th July 2nd August 12th August Mean 
Baawutawuta 17.36 15.08 15.92 19.78 16.48 16.76 16.90 
Padi-Tuya 24.64 36.36 38.36 75.06 38.52 64.48 46.24 
Songotra 20.80 18.64 20.98 27.78 18.08 26.56 22.14 
Zaayura 23.96 22.36 24.64 35.44 18.62 33.16 26.36 
Mean 21.69 23.11 24.98 39.52 22.93 35.24  
Lsd (P=0.05): Planting date = 4.86, variety = 3.96, planting date x variety = 9.71 
 
Results in Table 5 show that interaction effect of planting date and variety for 
plant heights at first harvest was significantly different with Padi-Tuya planted on 
25th July producing significantly taller plants.  The varieties also showed 
significant differences in mean heights at this plant age. Padi-tuya produced plants 
significantly taller than the other three varieties; Zaayura had plants also taller 
than both Songotra and Baawutawuta while Songotra was significantly taller than 
Baawutawuta. Significant differences in plant height among planting dates at this 
plant age indicate that except for the sixth planting date (12th August), planting on 
25th July produced significantly taller plants than the other planting dates. The first 
planting date (20th June) and the last planting date (12th August) did not show 
significant difference in plant height, but both produced significantly taller plants 
than planting on both 30th June and 2nd August. 
 
 
 
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Table 5: Effect of planting date and variety of cowpea on plant height (cm) at 
         first harvest (49 DAP). 
 
 Planting Dates  
Varieties 20th June 30th June 12th July 25th July 2nd August 12th August Mean 
Baawutawuta 22.0 16.3 21.4 29.4 18.6 20.4 21.35 
Padi-Tuya 61.2 53.4 75.7 102.5 77.8 99.8 78.40 
Songotra 33.3 24.6 26.8 33.1 27.0 31.8 29.43 
Zaayura 47.6 33.0 38.7 53.4 25.6 40.6 39.82 
Mean 41.03 31.83 40.65 54.6 37.25 48.15  
Lsd (P=0.05): Planting date = 7.44, variety = 6.08, planting date x variety = 14.90 
 
4.1.2 Stem diameter 
There was no significant (P<0.05) sowing date by variety interaction at all the 
stages of plant age for stem diameter. However there were significant differences 
among sowing dates and among cowpea varieties evaluated. Mean stem diameter 
recorded at the late vegetative growth stage (35 DAP) of the plants indicated that 
planting on both 25th July and on 12th August produced stems that were not 
significantly different in diameter but were different from all the other planting 
dates planted (Table 6). Planting on 20th June was also not different from both 
plantings of 30th June and 2nd August but was significantly larger than plants of 
12th July planting. Mean stem diameter among varieties at this age of plants show 
that Padi-Tuya and Zaaayura were not significantly different in diameter but were 
both significantly larger than Songotra and Baawutawuta which were also not 
significantly different from each other (Table 6). 
 
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Table 6: Effect of planting date and variety of cowpea on stem diameter (mm) at 
           late vegetative stage (35 DAP). 
 
 Planting Dates  
Varieties 20th June 30th June 12th July 25th July 2nd August 12th August Mean 
Baawutawuta 4.10 3.89 3.79 4.64 4.10 4.77 4.21 
Padi-Tuya 4.80 4.44 4.56 5.27 4.52 4.95 4.76 
Songotra 4.06 3.98 3.73 4.77 4.19 4.92 4.28 
Zaayura 4.94 4.76 3.88 5.32 4.41 5.01 4.72 
Mean 4.48 4.27 3.99 5.00 4.30 4.91  
Lsd (P=0.05): Planting date = 0.35, variety = 0.29, planting date x variety = NS 
 
At flowering there were significant differences in mean stem diameter among 
varieties. Zaayura and Padi-Tuya produced plants with marginally bigger stems, 
whilst Bawutawuta produced plants with the smallest stems (Table 7). A similar 
trend was exhibited by the varieties at first harvest with Zaayura and Padi-Tuya 
producing plants with the biggest mean stems whilst Songotra produced plants 
with the smallest stems (Table 8). Generally, planting on 25th July produced 
bigger mean stems at both flowering and at first harvest (Tables 7 and 8). At 
flowering, planting on 20th June, 25th July and 12th August were similar in mean 
stem diameter but were all significantly different from plantings of 30th June, 12th 
July and 2nd August (Table 7). Bawutawuta, Padi-Tuya and Songotra all produced 
plants with the biggest stems when planted on the 25th of July.  
 
 
 
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Table 7: Effect of planting date and variety of cowpea on stem diameter (mm) 
     at flowering (42 DAP). 
 
 Planting Dates  
Varieties 20th June 30th June 12th July 25th July 2nd August 12th August Mean 
Baawutawuta 5.26 4.64 4.33 5.68 5.05 5.45 5.07 
Padi-Tuya 6.22 4.91 4.96 6.45 5.24 5.87 5.61 
Songotra 5.43 4.70 4.51 5.60 4.88 5.56 5.12 
Zaayura 6.65 5.45 4.75 6.31 5.43 5.80 5.73 
Mean 5.89 4.92 4.64 6.01 5.15 5.67  
Lsd (P=0.05): Planting date = 0.43, variety = 0.35, planting date x variety = NS 
 
At first harvest (Table 8), planting on 20th June and 25th July were not 
significantly different in mean stem diameter, but produced mean stem diameters 
that were significantly different from the rest of the planting dates. Bawutawuta, 
Padi-Tuya and Zaayura all produced plants with the biggest stems when planted 
on the 25th of July and plants with the smallest stems for Baawutawuta and Padi-
Tuya only when planted on the 30th of June while Zaayura produced smallest 
plants with the planting of 12th July (Table 8). However, Songotra produced plants 
with bigger stems when planted on the 20th of June and plants with the smallest 
stems when planted on 30th of June. 
 
 
 
 
 
 
 
 
 
 
 
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Table 8: Effect of planting date and variety of cowpea on stem diameter (mm) 
         at first harvest (49 DAP). 
 
 Planting Dates  
 
Varieties 20th June 30th June 12th July 25th July 2nd August 12th August Mean 
Baawutawuta 6.17 5.28 5.43 6.73 6.34 6.12 6.01 
Padi-Tuya 7.05 5.47 5.92 7.27 6.92 6.44 6.51 
Songotra 6.44 5.48 5.56 6.36 6.04 5.90 5.96 
Zaayura 7.11 6.27 5.89 7.28 6.72 6.14 6.57 
Mean 6.69 5.63 5.70 6.91 6.50 6.15  
Lsd (P=0.05): Planting date = 0.47, variety = 0.39, planting date x variety = NS 
 
4.1.3 Dry stem weight 
No significant interaction effects between planting date and varieties of cowpea 
on dry stem weight per plant was observed at the various ages of plant growth 
(Tables 9, 10, and 11). However, varieties and planting dates showed significant 
differences among dry stem weight per plant at certain stages of growth. At 35 
DAP, the 2nd, 3rd and 4th planting dates (30th June, 12th July and 25th July)  stem 
dry weights were all significantly different from the other planting dates but were 
in themselves non-significant (Table 9). Planting on 20th June, 2nd August and 12th 
August also produced stem dry weights that were not significantly different.  
 
Significantly different dry stem weight among varieties was also observed at the 
vegetative stage (35 DAP) with Padi-Tuya producing significantly higher stem dry 
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weight compared with the other varieties. Zaayura was also significantly different 
from both Baawutawuta and Songotra (Table 9). 
 
Table 9: Effect of planting date and variety of cowpea on stem dry weight (g) 
           at late vegetative stage (35 DAP). 
 
 Planting Dates  
Varieties 20th June 30th June 12th July 25th July 2nd August 12th August Mean 
Baawutawuta 1.54 1.84 1.80 1.82 1.38 1.22 1.60 
Padi-Tuya 2.46 3.26 3.26 3.28 2.46 1.72 2.74 
Songotra 1.64 1.78 1.68 1.76 1.64 1.56 1.68 
Zaayura 2.04 2.36 2.34 2.90 2.22 1.76 2.27 
Mean 1.92 2.31 2.27 2.44 1.92 1.57  
Lsd (P=0.05): Planting date = 0.38, variety = 0.31, planting date x variety = NS 
 
At flowering stage, stem dry weight was significantly different among planting 
dates (Table 10). Planting on 25th July resulted in significantly different stem dry 
weight than all the other planting dates. It is observed that planting on 30th June 
produced dry stem weights that were significantly different from plantings of 20th 
June, 12th July, 2nd August and 12th August. There was no significant difference 
among plantings of 20th June, 12th July and 12th August (Table 10). 
 
 
 
 
 
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Table 10: Effect of planting date and variety of cowpea on stem dry weight (g) 
                                     at flowering (42 DAP). 
 
 Planting Dates  
Varieties 20th June 30th June 12th July 25th July 2nd August 12th August Mean 
Baawutawuta 2.66 4.20 3.00 7.24 1.48 2.68 3.54 
Padi-Tuya 3.22 5.20 3.72 8.64 3.02 3.64 4.57 
Songotra 3.42 4.76 3.42 8.24 2.40 3.98 4.37 
Zaayura 2.78 4.16 3.06 8.12 1.90 3.36 3.90 
Mean 3.02 4.58 3.30 8.06 2.20 3.42  
Lsd (P=0.05): Planting date = 1.07, variety = NS, planting date x variety = NS 
 
For stem dry weight at first harvest, the interaction between planting date and 
variety was not significant. However, there were significant differences among 
planting dates as well as varieties (Table 11). Padi-Tuya and Zaayura produced 
stem dry weights that were both significantly higher than both Baawutawuta and 
Songotra. Stem dry weights among the first four planting dates were similar at 
first harvest. However, plantings of 30th June and 25th July produced stem dry 
weights that were significantly different from those produced for both plantings in 
August (Table 11).   
 
 
 
 
 
 
 
 
 
 
 
 
 
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Table 11: Effect of planting date and variety of cowpea on stem dry weight (g) 
                                     at first harvest (49 DAP). 
 
 Planting Dates  
Varieties 20th June 30th June 12th July 25th July 2nd August 12th August Mean 
Baawutawuta 6.10 7.90 6.76 6.86 2.02 3.82 5.58 
Padi-Tuya 7.10 9.46 8.96 8.38 5.00 7.18 7.68 
Songotra 4.36 5.62 6.12 6.12 4.58 4.82 5.27 
Zaayura 6.98 9.06 7.14 10.28 3.38 5.24 7.01 
Mean 6.14 8.01 7.25 7.91 3.75 5.27  
Lsd (P=0.05): Planting date = 2.01, variety = 1.65, planting date x variety = NS 
 
4.1.4 Number of leaves 
Significant differences of planting dates and varieties on number of leaves per 
plant at late vegetative stage (35 DAP) were observed. There was no significant 
variety x planting date on cowpea number of leaves (Table 12). Songotra 
produced significantly lower number of leaves at this stage of plant growth. 
Though Baawutawuta and Padi-Tuya were not significantly different in their leaf 
numbers at 35 DAP, they both produced significantly different leaf numbers than 
Zaayura (Table 12). Planting dates also showed significant differences among leaf 
numbers at late vegetative growth stage (35 DAP). Planting on 25th July was 
significantly different from planting on 12th July and also different from all the 
other planting dates in number of leaves produced per plant was observed. Also 
plantings of 12th July and 2nd August were similar but produced leaf numbers 
significantly different from planting of 12th August (Table 12). 
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At flowering there was no significant interactions between cowpea varieties and 
planting dates, however, there were significant differences among varieties and 
the contrasting planting dates (Table 13). Baawutawuta produced significantly 
higher mean number of leaves than Padi-Tuya and Zaayura. The mean leaf 
numbers of Padi-Tuya and Songotra were not significantly different but were both 
significantly different from Zaayura. The 2nd, 3rd, 4th and 6th planting dates didn’t 
produce significantly different mean leaf numbers at flowering but were all 
significantly different from mean number of leaves produced at the 5th planting 
date (Table 13). 
 
Table 14 shows number of leaves per plant at first harvest (49 DAP). There were 
no significant differences among varieties and also interaction between planting 
dates and varieties was not significant. However, there was significant difference 
in planting dates. The 3rd planting date (12th July) produced significantly higher 
number of leaves at first harvest than the 20th June, 25th July, 2nd August and 12th 
August planting dates (Table 14). 
 
 
 
 
 
 
 
 
 
 
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Table 12: Effect of planting date and variety of cowpea on number of leaves 
             at late vegetative stage (35 DAP). 
 Planting Dates  
Varieties 20th June 30th June 12th July 25th July 2nd August 12th August Mean 
Baawutawuta 40.80 45.60 52.80 60.40 48.20 36.40 47.37 
Padi-Tuya 40.80 44.00 49.80 56.40 46.80 38.00 45.97 
Songotra 33.20 34.40 36.00 38.00 34.80 32.20 34.77 
Zaayura 36.80 37.20 40.00 43.60 40.00 36.80 39.07 
Mean 37.90 40.30 44.65 49.60 42.45 35.85  
Lsd (P=0.05): Planting date = 5.04, variety = 4.12, planting date x variety = NS 
 
 
 
Table 13: Effect of planting date and variety of cowpea on number of leaves 
             at flowering (42 DAP). 
 
 Planting Dates  
Varieties 20th June 30th June 12th July 25th July 2nd August 12th August Mean 
Baawutawuta 52.2 65.8 65.8 85.6 39.0 72.8 63.53 
Padi-Tuya 52.0 52.8 52.8 52.4 52.0 54.0 52.67 
Songotra 53.4 61.0 61.0 67.4 46.2 69.4 59.73 
Zaayura 39.0 44.2 44.2 48.6 34.2 49.8 43.33 
Mean 49.1 56.00 56.00 63.50 42.80 61.50  
Lsd (P=0.05): Planting date = 10.00, variety = 8.17, planting date x variety = NS 
 
 
 
 
 
 
 
 
 
 
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Table 14: Effect of planting date and variety of cowpea on number of leaves 
             at first harvest (49 DAP). 
 
 Planting Dates  
Varieties 20th June 30th June 12th July 25th July 2nd August 12th August Mean 
Baawutawuta 59.4 77.0 85.2 69.4 38.4 45.6 62.50 
Padi-Tuya 58.8 68.2 87.4 49.4 49.4 49.2 60.40 
Songotra 52.0 56.0 66.6 46.0 47.8 48.8 52.87 
Zaayura 57.8 68.4 78.6 59.0 41.8 53.6 59.87 
Mean 57.00 67.40 79.45 55.95 44.35 49.30  
Lsd (P=0.05): Planting date = 12.20, variety = NS, planting date x variety = NS 
 
4.1.5 Dry leaf weight per plant 
There was no significant variety by planting date interaction across the various 
sampling dates on leaf dry weight at flowering and at first harvest (Tables 15, and 
16). However, there was significant variety and planting dates effects on cowpea 
leaf dry matter. Planting on 25th of July produced significantly greater leaf dry 
matter than the rest of the planting dates at the flowering stage (Table 15). 
Plantings of 30th June, 12th July and 12th August were similar but all yielded 
significantly higher leaf dry matter than planting on 2nd August. Means of 
varieties indicate that Padi-Tuya produced significantly higher leaf dry matter than 
the rest of the varieties (Table 15). 
 
At first harvest, planting on 12th July produced significantly higher leaf dry matter 
than the rest of the planting dates (Table 16). At this stage also, Padi-Tuya 
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produced significantly higher leaf dry matter than the other three varieties (Table 
16). 
 
Table 15: Effect of planting date and variety of cowpea on weight (g) of 
             dry leaf weight at flowering (42 DAP). 
 
 Planting Dates  
Varieties 20th June 30th June 12th July 25th July 2nd August 12th August Mean 
Baawutawuta 4.02 5.38 5.34 7.86 2.72 5.46 5.13 
Padi-Tuya 5.72 6.26 6.32 6.90 5.22 6.80 6.20 
Songotra 4.52 5.06 5.02 5.82 4.00 5.24 4.94 
Zaayura 3.64 4.12 4.34 5.42 3.24 4.36 4.19 
Mean 4.48 5.21 5.26 6.50 3.80 5.47  
Lsd (P=0.05): Planting date = 0.99, variety = 0.81, planting date x variety = NS 
 
Table 16: Effect of planting date and variety of cowpea on weight (g) of 
             dry leaf weight at first harvest (49 DAP). 
 
 Planting Dates  
Varieties 20th June 30th June 12th July 25th July 2nd August 12th August Mean 
Baawutawuta 5.14 6.88 8.12 5.66 2.62 4.16 5.43 
Padi-Tuya 6.94 7.10 8.52 5.66 5.82 7.66 6.95 
Songotra 5.10 5.54 6.88 4.22 4.84 4.44 5.17 
Zaayura 5.42 6.14 6.68 5.64 4.40 4.92 5.53 
Mean 5.65 6.42 7.55 5.30 4.42 5.30  
Lsd (P=0.05): Planting date = 1.57, variety = 1.28, planting date x variety = NS 
 
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4.1.6 Number of branches 
At flowering, information on interaction between planting date and variety 
indicated not significant but the production of branches by Songotra was 
significantly different from both Baawutawuta and Padi-Tuya but not different 
from Zaayura (Table 17). Baawutawuta recorded the least number of branches 
while Songotra recorded the highest number.  There was significant difference 
(P<0.05) within planting dates in the number of branches on the main stems were 
determined (Table 17). Planting on the 12th August produced significantly lower 
number of branches than the other planting dates while planting on 30th June 
produced significantly higher number of branches than planting in July and 
August (Table 17). Baawutawuta and Padi-Tuya recorded high numbers of 
branches on the main stem when planted on 25th July while both Songotra and 
Zaayura recorded high branch numbers when planted on 30th June but all varieties 
recorded lowest number of branches when planting was done on 12th August.  
 
Table 17: Effect of planting date and variety of cowpea on number of 
             branches from main stem at flowering (42 DAP). 
 Planting Dates  
Varieties 20th June 30th June 12th July 25th July 2nd August 12th August Mean 
Baawutawuta 3.80 4.20 4.00 4.40 2.80 2.40 3.60 
Padi-Tuya 4.00 4.40 3.60 4.80 4.20 1.00 3.67 
Songotra 4.60 6.00 4.20 4.60 4.80 2.00 4.37 
Zaayura 4.00 4.40 3.80 4.20 3.80 3.00 3.87 
Mean 4.10 4.75 3.90 4.50 3.90 2.10  
Lsd (P=0.05): Planting date = 0.67, variety = 0.55, planting date x variety = NS 
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Data taken on branch numbers at first harvest did not show any significant effect 
of planting date or varieties (Table 18). The interaction between variety and 
planting date was also not significant.  However, Baawutawuta recorded high 
branch number with plantings of 25th July and 2nd August and recorded its lowest 
number with plantings of 30th June and 12th August. Padi-Tuya on the other hand 
recorded higher branch numbers when planted on 2nd August than when planted 
on 12th August. For both Songotra and Zaayura, high branch numbers were 
recorded when planted on 30th June while planting on 12th August recorded the 
least branch numbers. Generally the lowest number of branches at this stage were 
with 12th August planting. Baawutawuta produced the highest number of branches 
while Zaayura produced the least (Table 18). 
 
Table 18: Effect of planting date and variety of cowpea on number of 
                        branches from main stem at first harvest (49 DAP). 
 
 Planting Dates  
Varieties 20th June 30th June 12th July 25th July 2nd August 12th August Mean 
Baawutawuta 2.00 1.80 2.00 2.20 2.20 1.80 2.00 
Padi-Tuya 1.40 2.00 1.80 1.40 2.40 0.60 1.60 
Songotra 1.40 2.00 1.20 1.40 1.40 1.00 1.40 
Zaayura 1.20 1.60 1.20 1.20 1.40 1.00 1.27 
Mean 1.50 1.85 1.55 1.55 1.85 1.10  
Lsd (P=0.05): Planting date = NS, variety = NS, planting date x variety = NS 
 
 
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4.1.7 Roots dry weight 
Dry weight of roots was not significantly different at all three stages of plant 
growth when tested for interaction effect of planting dates and varieties of 
cowpea. There were however significant differences exhibited by planting dates 
and also varieties at all stages of growth. For the two growth stages, dry weights 
of roots were significantly different with planting on 25th July (Tables 19, and 20). 
The trend was almost the same with the different varieties as highest root dry 
weight was recorded for each variety on the planting of 25th July except Songotra 
which recorded highest root dry weight at first harvest with the planting of 12th 
July.       
 
Significant differences were observed with planting dates at flowering stage for 
dry weight of roots (Table 19). The fourth planting date (25th July) was 
significantly different from all the other planting dates but the third planting date 
(12th July) and sixth planting date (12th August) were not significantly different. 
Planting on 12th August was significantly different from plantings of 20th June, 
30th June and 2nd August, and again planting on both 12th July and 2nd August 
were not different but they were both significantly different from plantings of 20th 
and 30th June. Planting on 20th June was also significantly different from planting 
on 30th June in root dry weight. At this age of plants Padi-Tuya produced 
significantly higher root dry weight than the other varieties involved (Table 19). 
Zaayura was also significantly different from Baawutawuta. But Zaayura and 
Songotra as well as Baawutawuta and Songotra were not significantly different 
from each other. 
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Table 19: Effect of planting date and variety of cowpea on dry weight (g) of 
             roots per plant at flowering (42 DAP). 
 
 Planting Dates  
Varieties 20th June 30th June 12th July 25th July 2nd August 12th August Mean 
Baawutawuta 0.56 0.30 0.78 1.26 0.70 0.88 0.75 
Padi-Tuya 0.90 0.50 1.02 1.62 1.00 1.36 1.07 
Songotra 0.46 0.24 0.90 1.58 0.80 0.76 0.79 
Zaayura 0.64 0.36 0.96 1.62 0.62 0.98 0.86 
Mean 0.64 0.35 0.92 1.52 0.78 1.00  
Lsd (P=0.05): Planting date = 0.14, variety = 0.12, planting date x variety = NS 
 
From Table 20 there were significant differences at first harvest stage of plants 
among planting dates and varieties. Both plantings of 12th July and 25th July did 
not show significant differences among themselves but were significantly 
different in weight of dry root per plant from the rest of the dates planted. Planting 
on 30th June was also significantly different with weight of dry roots per plant 
from planting on 12th August. However, planting on 20th June, 30th June and 2nd 
August were not significantly different.  Root dry weight for Padi-Tuya was 
significantly different from that of Baawutawuta, Songotra and Zaayura but there 
was no significant difference among the three latter varieties (Table 20).   
 
 
 
 
 
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Table 20: Effect of planting date and variety of cowpea on dry weight (g) of 
             roots per plant at first harvest (49 DAP). 
 
 Planting Dates  
Varieties 20th June 30th June 12th July 25th July 2nd August 12th August Mean 
Baawutawuta 0.92 1.14 1.50 1.36 0.74 0.78 1.07 
Padi-Tuya 1.28 1.44 1.76 1.94 1.34 1.20 1.49 
Songotra 0.92 1.04 1.42 1.30 0.96 0.88 1.09 
Zaayura 0.94 1.18 1.46 1.92 1.06 0.76 1.22 
Mean 1.02 1.20 1.54 1.63 1.03 0.91  
Lsd (P=0.05): Planting date = 0.26, variety = 0.21, planting date x variety = NS 
 
4.1.8 Dry biomass weight per plot 
At the vegetative stage, both planting date and interaction effect of planting date x 
variety did not show significant difference in dry biomass weight per plot (Table 
21). All the same Baawutawuta planted on 25th July produced the highest biomass 
weight per plot and planting on 12th August produced the least biomass weight. 
The highest biomass weight per plot for Padi-Tuya was recorded when planted on 
2nd August while its least figure was recorded when planted on 12th July. If not for 
the lowest dry biomass weight of Songotra, both Songotra and Zaayura reacted 
oppositely to Padi-Tuya with regard to dry biomass weight per plot. Their highest 
weights were recorded with the planting of 12th August while their lowest weights 
recorded when planted on 12th July and 25th July for Songotra and Zaayura 
respectively (Table 21). Significant difference was indicated with variety reactions 
at the vegetative stage with Padi-Tuya being significantly different from Songotra 
and Zaayura but similar to Baawutawuta which is also significantly different from 
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Songotra (Table 21). Baawutawuta was not significantly different from Zaayura 
and also Songotra and Zaayura were not significantly different from one another 
too.  
 
Table 21: Effect of planting date and variety of cowpea on dry biomass 
             (stems and leaves only) weight (kg) per plot after last harvest. 
 
 Planting Dates  
Varieties 20th June 30th June 12th July 25th July 2nd August 12th August Mean 
Baawutawuta 1.16 1.12 1.12 1.38 1.21 0.94 1.15 
Padi-Tuya 1.37 1.36 1.00 1.28 1.66 1.56 1.37 
Songotra 0.89 0.94 0.74 0.82 0.93 1.06 0.90 
Zaayura 1.02 1.04 1.00 0.90 1.00 1.20 1.03 
Mean 1.11 1.12 0.97 1.10 1.20 1.19  
Lsd (P=0.05): Planting date = NS, variety = 0.23, planting date x variety = NS 
 
4.1.9 Leaf area 
Interaction effect of planting date and varieties on leaf area were all significant 
(P<.05). Leaf area of Padi-Tuya was significantly different from that of Zaayura, 
Songotra and Baawutawuta (Table 22). Leaf area of Zaayura was also different 
from Baawutawuta and Songotra , while those of Baawutawuta and Songotra were 
similar. Planting on 25th July was significantly different from all the other dates 
invovled. Padi-Tuya produced largest leaves when planted on the 25th July and 
smallest leaf area with the planting of June 30th. Zaayura recorded its largest leaf 
area with the planting of 25th July and smallest when planted on 2nd August. 
Baawutawuta produced largest leaf area when planted on 20th June and smallest 
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leaf area when also planted on 2nd August. Songotra was similar to Padi-Tuya with 
largest leaf area produced when planted on 25th July and smallest when planted on 
30th June. However, Padi-Tuya produced the largest leaf area than the other 
varieties while Songotra produced the smallest leaves in terms of area (Table 22). 
 
Table 22: Effect of planting date and variety of cowpea on leaf area (cm2). 
 
 Planting Dates  
Varieties 20th June 30th June 12th July 25th July 2nd August 12th August Mean 
Baawutawuta 38.73 35.95 31.83 37.26 29.86 30.79 34.1 
Padi-Tuya 47.69 39.33 42.97 62.03 56.70 55.70 50.7 
Songotra 31.46 28.30 25.34 37.99 32.23 31.89 31.2 
Zaayura 47.45 42.10 39.21 56.29 30.49 32.54 41.3 
Mean 41.33 36.42 34.84 48.39 37.32 37.73  
Lsd (P=0.05): Planting date = 4.71, variety = 3.85, planting date x variety = 9.43 
 
      4.1.10 Plant canopy 
Plant canopy diameter was not significantly different with interaction effect 
between planting date and varieties. Planting dates also did not show significant 
difference (Table 23). However, there were significant differences among 
varieties. Songotra developed significantly smaller plant canopy than the other 
varieties. For Baawutawuta and Padi-Tuya, broadest diameters were recorded 
when planting took place on 25th July and smallest diameters were recorded when 
planting was done on the sixth planting date (12th August). Songotra developed 
broadest plant canopy diameters with the planting on 12th July and small 
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diameters when planting was done on 12th August, while Zaayura developed 
broadest canopy diameters with planting of 12th July and smallest diameter with 
planting on 2nd August. Considering the varieties (Table 23), Padi-Tuya generally 
developed broader canopy than the other varieties and Songotra developed 
smallest canopy.  
 
Table 23: Effect of planting date and variety of cowpea on canopy diameter (cm). 
 
 Planting Dates  
Varieties 20th June 30th June 12th July 25th July 2nd August 12th August Mean 
Baawutawuta 38.08 40.64 41.48 42.44 38.62 36.00 39.54 
Padi-Tuya 40.36 41.18 41.28 41.86 40.74 37.40 40.47 
Songotra 35.52 36.34 36.72 35.66 36.14 34.64 35.84 
Zaayura 40.46 40.46 40.94 39.64 37.24 37.60 39.39 
Mean 38.61 39.66 40.11 39.9 38.19 36.41  
Lsd (P=0.05): Planting date = NS, variety = 2.97, planting date x variety = NS 
 
     4.2 Flowering and podding 
     4.2.1 Days to first flower opening 
Number of days from planting to the day the first flower opened was not 
significantly affected by planting date and variety interaction (Table 24). The 
results however indicated that planting date produced significant differences. 
Planting on 25th July was significantly different from all other planting dates 
involved. It resulted in fewer numbers of days to first flower opening across all 
the varieties. The other dates on which planting was done were not significantly 
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different from one another even though mere figure differences in the number of 
days to first flowers opening are observed. Higher number of days to first flower 
opening for Baawutawuta was when it was planted on 2nd August. Padi-Tuya was 
late to produce first flowers when planting was on 12th August, while Songotra 
also delayed in producing first flowers with plantings of 30th June. Zaayura on the 
other hand was late to produce first flowers when planted on both 20th June and 
12th July. 
 
There were also significant differences among varieties used (Table 24). 
Baawutawuta took significantly higher number of days to produce first flowers 
than all the other varieties. Padi-Tuya was also significantly different from both 
Songotra and Zaayura in the number of days to first flower. Songotra and Zaayura 
did not exhibit significant differences among themselves with first flowers 
opening. Generally, Songotra was the earliest to flower (Table 24). 
 
     Table 24: Effect of planting date and variety of cowpea on days to first flower  
           opening. 
 
 Planting Dates  
Varieties 20th June 30th June 12th July 25th July 2nd August 12th August Mean 
Baawutawuta 40.20 40.20 39.20 37.60 40.40 39.60 39.5 
Padi-Tuya 37.40 38.40 37.80 36.60 38.00 38.60 37.8 
Songotra 36.00 37.60 36.60 34.80 36.00 36.60 36.3 
Zaayura 37.60 37.20 37.60 35.60 36.00 36.80 36.8 
Mean 37.80 38.35 37.80 36.15 37.60 37.90  
Lsd (P=0.05): Planting date = 0.85, variety = 0.69, planting date x variety = NS 
 
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4.2.2 Days to 50% flowering 
Interaction between planting dates and varieties was significant (Table 25). With 
all varieties, planting on 25th July produced plants that reached fifty percent (59%) 
flowers earliest. Planting any of the varieties earlier or later than 25th July 
generally produced plants that took longer days to reach 50% flowering. 
 
Table 25: Effect of planting date and variety of cowpea on days to 50%  
            flowering. 
 
 Planting Dates  
Varieties 20th June 30th June 12th July 25th July 2nd August 12th August Mean 
Baawutawuta 42.60 44.40 44.00 42.20 44.00 43.00 43.4 
Padi-Tuya 41.20 41.80 41.20 40.20 43.40 41.80 41.6 
Songotra 40.40 41.00 40.40 38.20 40.40 38.40 39.8 
Zaayura 41.60 41.60 42.20 38.40 40.00 38.40 40.4 
Mean 41.45 42.20 41.95 39.75 41.95 40.40  
Lsd (P=0.05): Planting date = 0.75, variety = 0.61, planting date x variety = 1.50 
 
4.2.3 Podding 
The number of days from planting to the day first pods appeared was observed. 
There was no significant interaction effect of planting date and varieties (Table 
26). Planting date however produced significant differences. Planting on 25th July 
had plants producing pods earlier than planting on other dates involved; and that 
planting on 20th June resulted in late podding. Planting on 20th June was 
significantly different from all other planting dates involved. 30th June, 12th July, 
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2nd August and 12th August planting dates were not different from one another but 
were all significantly different from the planting of 25th July. The Baawutawuta 
variety was the latest to set pods and was significantly different from the other 3 
varieties while Padi-Tuya was also significantly different from Songotra and 
Zaayura, but the latter two varieties were not significantly different (Table26). 
 
Table 26: Effect of planting date and variety of cowpea on days to first pod set. 
 
 Planting Dates  
Varieties 20th June 30th June 12th July 25th July 2nd August 12th August Mean 
Baawutawuta 42.00 41.80 40.40 39.20 41.60 41.40 41.1 
Padi-Tuya 41.00 40.00 40.00 38.00 39.80 40.40 39.9 
Songotra 39.80 39.20 39.60 36.60 38.00 38.20 38.6 
Zaayura 40.80 39.20 39.20 37.20 38.00 38.20 38.8 
Mean 40.90 40.05 39.80 37.75 39.35 39.55  
Lsd (P=0.05): Planting date = 0.78, variety = 0.64, planting date x variety = NS 
 
4.2.4 First harvest 
Significant interaction between planting date and varieties was observed for 
number of days taken from planting to first harvest (Table 27). For all varieties, 
number of days to first harvest was significantly lower with planting on 30th June 
than the other dates. Higher number of days to first harvest was observed with 
both planting on 20th June and 12th August. 
  
 
 
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Table 27: Effect of planting date and variety of cowpea on days to first harvest. 
 
 Planting Dates  
Varieties 20th June 30th June 12th July 25th July 2nd August 12th August Mean 
Baawutawuta 55.00 45.60 50.80 51.20 50.80 51.00 50.7 
Padi-Tuya 51.40 44.00 49.60 50.40 48.00 53.60 49.5 
Songotra 49.80 44.40 48.20 48.20 48.00 51.00 48.3 
Zaayura 51.40 44.00 49.00 49.20 49.40 51.00 49.0 
Mean 51.90 44.50 49.40 49.75 49.05 51.65  
Lsd (P=0.05): Planting date = 1.05, variety =0.86, planting date x variety = 2.10 
 
4.3 Yield and yield components 
4.3.1 Pod number per plant 
The number of green pods per plant when subjected to analysis of variance did not 
show any significant interaction effect between planting dates and cowpea 
varieties. There was also no significant difference among planting dates. 
However, there were significant differences among varieties (Table 28). 
Baawutawuta produced significantly higher number of green pods per plant than 
Padi-Tuya, Songotra and Zaayura while no significant differences were found 
among Padi-Tuya, Songotra and Zaayura. 
 
 
 
 
 
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Table 28: Effect of planting date and variety of cowpea on number of pods per  
            plant. 
 
 Planting Dates  
Varieties 20th June 30th June 12th July 25th July 2nd August 12th August Mean 
Baawutawuta 12.40 12.20 12.40 14.40 11.00 13.00 12.6 
Padi-Tuya 10.20 8.60 10.60 10.80 11.40 11.60 10.5 
Songotra 9.20 10.80 9.80 8.80 8.80 8.40 9.3 
Zaayura 9.00 12.60 10.60 10.20 9.40 9.40 10.2 
Mean 10.20 11.05 10.85 11.05 10.15 10.60  
Lsd (P=0.05): Planting date = NS, variety = 1.82, planting date x variety = NS 
 
4.3.2 Green pod weight per plant 
The weight of green pods was not significantly different among planting dates, 
and the interaction between planting dates and varieties. However, varieties 
exhibited significant differences among themselves (Table 29). Padi-Tuya was 
significantly different from both Songotra and Zaayura but not different from 
Baawutawuta. Songotra, Zaayura and Baawutawuta were similar in the amount of 
green pod weight produced. Generally Padi-Tuya recorded the highest weight of 
green pods per plant while Zaayura recorded the least weight of green pods per 
plant (Table 29).  
 
 
 
 
 
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Table 29: Effect of planting date and variety of cowpea on weight (g) of green  
            pods per plant. 
 
 Planting Dates  
Varieties 20th June 30th June 12th July 25th July 2nd August 12th August Mean 
Baawutawuta 51.1 41.7 44.3 53.2 41.3 47.9 46.6 
Padi-Tuya 61.5 47.9 51.6 50.6 53.3 50.8 52.6 
Songotra 50.6 49.5 43.8 43.1 39.4 32.5 43.1 
Zaayura 38.3 46.3 33.3 39.4 41.0 48.6 41.1 
Mean 50.38 46.35 43.25 46.58 43.75 44.95  
Lsd (P=0.05): Planting date = NS, variety = 8.81, planting date x variety = NS 
 
4.3.3 Green pod yield per hectare 
Table 30 shows green pod yield per hectare. This was not significantly affected by 
planting date, variety, and interaction effect of planting date and variety (Table 
30).  
 
 
 
 
 
 
 
 
 
 
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Table 30: Effect of planting date and variety of cowpea on green pod yield (tons)  
            per hectare. 
 
 Planting Dates  
Varieties 20th June 30th June 12th July 25th July 2nd August 12th August Mean 
Baawutawuta 4.26 3.47 3.69 4.44 3.44 3.99 3.9 
Padi-Tuya 5.12 3.99 4.30 4.21 4.44 4.23 4.4 
Songotra 4.21 4.13 3.65 3.59 3.28 2.70 3.6 
Zaayura 3.19 3.86 2.78 3.28 3.42 4.05 3.4 
Mean 4.19 3.86 3.60 3.88 3.64 3.74  
 Lsd (P=0.05): Planting date = NS, variety = NS, planting date x variety = NS 
 
4.3.4 Mean pod weight 
Table 31 shows mean green pod weight. There were significant differences in 
planting date effect, variety effect. The interaction between planting date and 
varieties was also significant. Planting Baawutawuta on 30th June produced 
significantly lower mean pods than planting on 20th June. Except with the planting 
of 30th June, Padi-Tuya planted on 20th June produced mean pod weighst that were 
significantly higher than pods from plantings of the other dates. Planting Padi-
Tuya on 30th June produced significantly heavier pods than planting on 25th July, 
2nd August and 12th August. Songotra planted on 20th June and 25th July did not 
show any significant difference in mean pod weight but planting on 20th June 
produced significantly heavier pods than planting on the other dates, while 
planting on 25th July was significantly different from planting on 12th August. 
Planting Zaayura on 12th August produced significantly heavier mean pods than 
planting on 20th June, 30th June, 12th July and 25th July. 
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Table 31: Effect of planting date and variety of cowpea on mean pod weight (g)  
            of green pods. 
 
 Planting Dates  
Varieties 20th June 30th June 12th July 25th July 2nd August 12th August Mean 
Baawutawuta 4.12 3.32 3.57 3.67 3.70 3.63 3.7 
Padi-Tuya 6.02 5.52 4.87 4.53 4.56 4.33 5.0 
Songotra 5.50 4.62 4.47 4.90 4.50 4.14 4.7 
Zaayura 4.17 3.72 3.09 3.77 4.41 4.98 4.0 
Mean 4.95 4.29 4.00 4.22 4.29 4.27  
    Lsd (P=0.05): Planting date = 0.36, variety = 0.29, planting date x variety = 0.72 
 
4.3.5 Number of seeds per pod 
Table 32 shows the number of seeds per pod. There were significant differences in 
planting dates, varieties of cowpea, and the interaction between planting dates and 
varieties. The interaction between planting date and variety indicated that planting 
Songotra on 25th July produced significantly greater number of seeds per pod than 
planting on 2nd August, while planting Zaayura on 12th August produced 
significantly greater number of seeds per pod than planting it on both 30th June 
and 12th July (Table 32). Both Baawutawuta and Padi-Tuya did not show 
significant interaction with planting dates. 
 
 
 
 
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Table 32: Effect of planting date and variety of cowpea on number of seeds per  
             pod. 
 
 Planting Dates  
Varieties 20th June 30th June 12th July 25th July 2nd August 12th August Mean 
Baawutawuta 12.20 12.00 12.60 12.40 12.80 12.80 12.5 
Padi-Tuya 9.40 9.20 9.00 9.00 10.60 9.60 9.5 
Songotra 10.60 10.40 10.60 12.00 9.20 10.80 10.6 
Zaayura 9.00 8.40 6.60 8.80 9.80 10.60 8.9 
Mean 10.3 10 9.7 10.55 10.6 10.95  
Lsd (P=0.05): Planting date = 0.98, variety = 0.80, planting date x variety = 1.96 
 
4.4 Pod quality 
4.4.1 Pod length 
Significant differences were recorded with planting dates and varieties but their 
interaction was not significant (Table 33). Planting on 20th June produced 
significantly longer pods than planting on 30th June, 25th July, 2nd August and 12th 
August but this was not significantly different from planting on 12th July. Planting 
on 12th July was also significantly different from planting on 30th June, 2nd August 
and 12th August. There were no significant differences in pod length among 
planting on 30th June, 25th July, 2nd August and 12th August. Significantly longer 
pods were produced by the Padi-Tuya variety than the other varieties. Though 
Baawutawuta produced the shortest mean pod, this was not significantly different 
from those of Baawutawuta, Songotra, and Zaayura.  
 
 
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Table 33: Effect of planting date and variety of cowpea on pod length (cm). 
 
 Planting Dates  
Varieties 20th June 30th June 12th July 25th July 2nd August 12th August Mean 
Baawutawuta 16.28 14.82 15.98 15.81 15.04 14.40 15.4 
Padi-Tuya 17.80 16.57 17.24 16.07 16.42 15.30 16.6 
Songotra 16.28 14.65 16.86 15.93 15.20 15.70 15.8 
Zaayura 16.10 15.31 15.40 15.40 14.58 15.83 15.4 
Mean 16.61 15.34 16.37 15.80 15.31 15.31  
Lsd (P=0.05): Planting date = 0.72, variety = 0.59, planting date x variety = NS 
 
4.4.2 Pod diameter 
There were significant differences among varieties, sowing dates and also the 
interaction between varieties and sowing dates with regards to pod diameter. All 
the varieties produced significantly larger pods when planted on the 12th August 
than planting on all the other dates (Table 34). Baawutawuta, Padi-Tuya and 
Zaayura planted on 20th June, 30th June, and 2nd August did not show significant 
differences in pod diameter, but were all significantly different from both 
plantings in July. Planting of Songotra on 20th June, 30th June and 2nd August all 
produced pods that were significantly larger than pods produced when planted in 
July. There was a significant pod diameter difference when Songotra was planted 
on 20th June than when planted on 2nd August (Table 34). 
 
 
 
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Table 34: Effect of planting date and variety of cowpea on pod diameter (mm). 
 
 Planting Dates  
Varieties 20th June 30th June 12th July 25th July 2nd August 12th August Mean 
Baawutawuta 6.95 6.91 4.74 5.06 6.47 10.34 6.7 
Padi-Tuya 7.58 7.48 5.96 6.34 7.03 12.56 7.8 
Songotra 7.76 7.49 5.33 5.83 6.75 13.34 7.7 
Zaayura 7.40 7.48 5.93 6.28 7.31 13.59 8.0 
Mean 7.42 7.34 5.49 5.88 6.89 12.46  
Lsd (P=0.05): Planting date = 0.31, variety = 0.25, planting date x variety = 0.61 
 
4.4.3 Pod fibre content 
Results obtained from analysis of green pods for their fibre content showed 
significance in interaction between planting date and variety (Table 35). Planting 
of all the varieties on 12th August was significantly different from all other 
planting dates and for Baawutawuta planting also on 20th June and on 2nd August 
were both significantly different from planting on both 12th and 25th July. Results 
obtained from planting on 20th June, 30th June and 2nd August were not different 
from one another just as planting on 12th and 25th July were also not different from 
each other. For the other three varieties: Padi-Tuya, Songotra and Zaayura, except 
for planting on 12th August, all the other planting dates were not different from 
one another (Table 35). 
 
 
 
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Table 35: Effect of planting date and variety of cowpea on fibre content (g/100g)  
            of green pods. 
 
 Planting Dates  
Varieties 20th June 30th June 12th July 25th July 2nd August 12th August Mean 
Baawutawuta 2.70 2.69 2.64 2.61 2.71 2.78 2.7 
Padi-Tuya 1.88 1.87 1.88 1.83 1.84 1.99 1.9 
Songotra 2.00 1.99 1.99 1.99 2.04 2.07 2.0 
Zaayura 2.13 2.16 2.13 2.14 2.17 2.20 2.1 
Mean 2.18 2.18 2.16 2.14 2.19 2.26  
Lsd (P=0.05): Planting date = 0.02, variety = 0.02, planting date x variety = 0.05 
 
4.5 Correlation among some parameters of the cowpea experiment 
Correlation analysis was carried out on some of the parameters and the results 
revealed that there were also positive correlations among some of them as shown 
in the correlation matrix in Table 36. Plant height at first harvest (PHFH) 
positively correlated with Stem diameter at first harvest (SDFH), Number of 
leaves at first harvest (Lno.FH), Pods per plant (PPlt), Mean pod weight (MPW), 
Leaf area (LA), Plant canopy (PltCano), Pod diameter (PD) and Pod length (PL) 
while pods per plant (PPlt) was positively correlated with Leaf area (LA), Plant 
canopy (PltCano) and Pod length (PL). In other relations, Stem diameter at first 
harvest (SDFH) also was positively correlated with Number of branches at first 
harvest (Bno.FH), Pods per plant (PPlt), Mean pod weight (MPW), Leaf area 
(LA), Plant canopy (PltCano), and Pod length (PL) while Mean pod weight 
(MPW) was positively correlated with Leaf area (LA), Pod diameter (PD) and Pod 
length (PL). 
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Table 36: Correlation matrix of some parameters 
PHFH 1.000       
SDFH 0.411** 1.000      
Lno.FH 0.056 -0.121 1.000     
Bno.FH -0.063 0.077 0.380** 1.000    
DFF -0.136 -0.191 0.132 -0.042 1.000   
PPlt 0.081 0.406** 0.245* 0.043 0.207* 1.000  
MPW 0.268* 0.116 -0.198 -0.004 -0.320 -0.109 1.000 
LA 0.701** 0.481** 0.082 0.016 -0.066 0.190* 0.142  1.000   
PltCano 0.177 0.290* 0.251* 0.062 0.077 0.350** -0.001  0.271* 1.000 
PD 0.140 -0.011 -0.223 -0.494 -0.258 -0.057 0.161 -0.006-0.210       1.000   
PL 0.292* 0.165 0.082 -0.024 -0.082 0.182* 0.530** 0.194* 0.220*     -0.091   1.000 
Yld/Ha 0.268* 0.446** 0.120 0.046 0.017 0.826** 0.441** 0.273* 0.308       0.035    0.457**    1.000 
 PHFH SDFH      Lno_FH   Bno_FH       DFF         PPlt          MPW          LA           PltCano        PD       PL             Yld/Ha 
 
    *=p=0.05,         **=0.01 
Legend: PHFH = Plant height at first harvest, SDFH = Stem diameter at first harvest, Lno.FH = Number of leaves at first harvest, 
               Bno.FH = Number of branches at first harvest, DFF = Days to 50% flowering, PPlt = Pods per plant, MPW = Mean pod  
    weight, LA = Leaf area, PltCano = Plant canopy, PD = Pod diameter, PL = Pod length, Yld/Ha
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CHAPTER FIVE 
                 5.0 DISCUSSION 
In this chapter the results obtained from the field experiments conducted at the 
Manga Out-Station of the Savanna Agricultural Research Station (S. A. R. I.) 
during the 2012 cropping season on the effect of planting date and four varieties o 
cowpea on green pod production are discussed. 
 
5.1Effect of Planting Date and Varieties on: 
5.1.1 Crop Growth 
5.1.1.1 Plant Height 
Interaction effects were observed from the fifth week after sowing (WAS). Data 
on plant heights taken on 5th, 6th, and 7th WAS generally showed that there were 
significant differences among planting dates, some of the varieties, and also 
interaction between planting dates and varieties. Both Baawutawuta and Songotra 
did not show significant interact on differences at the three growth stages that 
plant height was recorded but Padi-Tuya and Zaayura showed. Both varieties: 
Padi-Tuya and Zaayura, planted on 25th July produced significantly taller plants 
when plant height was recorded at 35, 42 and 49 DAP. At 35 DAP, Padi-Tuya 
planted on 12th August produced significantly taller plants than both plantings in 
June but was similar to plantings on both 12th July and 2nd August while both 
plantings in June were also not significantly different in plant height. Zaayura 
planted on 25th July produced significantly taller plants than when it was planted 
on 2nd August but similar in height to all other dates it was planted. Plant height 
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records indicated that at 42 DAP, Padi- Tuya planted on 12th August also 
produced significantly taller plants than the other dates it was planted on except 
25th July. Planting on 30th June, 12th July and 2nd August to Padi-Tuya were 
similar but produced significantly taller plants than planting on 20th June. At 42 
DAP Zaayura planted on 12th August also produced plants that were significantly 
taller than those planted on 30th June and 2nd August but was similar to planting of 
25th July, while planting on 20th June, 12th July and 12th August were not 
significantly different in height. At 49 DAP, except 25th July, Padi-Tuya planted 
on 12th August produced plants that were significantly taller than the other 
planting dates. Planting on 2nd August was also significantly different in height 
from both plantings in June but was similar to the planting of 12th July. Planting of 
Padi-Tuya on 12th July was not significantly different from planting on 20th June 
but significantly different in height from planting on 30th June. At 49 DAP 
Zaayura planted on 20th June, 30th June, 12th July and 12th August did not produce 
plants that were significantly different in height from one another; meanwhile 
planting the variety on 2nd August also produced plants that were significantly 
shorter than those planted on 20th June and 12th August. There was no significant 
difference among planting Zaayura on 30th June, 12th July and 2nd August. 
Generally, at all the plant growth stages that plant height measurements were 
taken, planting the varieties on 25th July yielded significantly taller plants (Tables 
3, 4 and 5). There were differences in plant height among the varieties and that 
may be due to genetic variations. Cowpea varieties exhibited taller plants with late 
planting in each of the months that planting was done and with planting on 25th 
July producing tallest plants (Tables 3 and 4). This contradicts the findings of 
Adjei-Twum, (1978); Sayeed, (1988); Yadev, (1999); Incalcaterra et al., (2000); 
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Abdou-Razakou, (2013) and Rajesh, (2010) who all reported higher plants with 
early planting, but agrees with the findings of Norman, (1981) that planting in 
April to August produced significantly higher length of pineapple peduncle. It is 
therefore important to consider planting these cowpea varieties after mid-July if 
taller plants that also keep green pods above ground, thereby avoiding soil 
contamination are a goal. It is also evident from the results that plant height is 
positively correlated to other parameters (Table 37) including stem diameter (r = 
0.411**), pods per plant (r = 0.081), mean pod weight (r = 0.268*) and yield per 
hectare (r = 268*). Though some of the correlations are weak, the results show 
that plant height has a reflection on the number of pods per plant and mean pod 
weight. This finding is similar to the reports by Kuruvadi and Escobar (1987) that 
worked on soya bean and found that, yield and number of pods per plant is 
associated.  
 
5.1.1.2 Stem Diameter 
Stem diameter was observed with the aim of finding varieties and planting dates 
that will produce thick stems. Thick stems have an added advantage of being able 
to support heavy vegetative growth and pods. There was no stage of plant growth 
that stem diameter showed significant interaction between planting date and 
varieties. Varieties exhibited significant differences among themselves which is in 
agreement with the report of Abdou-Razakou, (2013) in his study to select 
drought tolerant varieties of cowpea. Baawutawuta and Songotra generally 
recorded thin stems that were not significantly different from one another. 
Baawutawuta increased slowly in stem diameter as observed during the first 42 
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DAP; considering that it all along to this period produced the thinnest stems. Padi-
Tuya and Zaayura produced larger stems which were not significantly different 
from one another but were both significantly different from both Baawutawuta 
and Songotra. Stems were also thick enough and held plant parts including pods 
above ground, which is a vital characteristic of erect varieties. Except 
Baawutawuta and Songotra at 35 DAP, Zaayura at 42 DAP and again Songotra at 
49 DAP, planting the varieties on 25th July constantly produced larger stems 
across all planting dates. This observation does not agree with the report by 
Norman, (1981) that planting date had no significant difference on peduncle of 
pineapple, while Amankwatia, (1979) and Singh, (1992) reported of reduced 
stems of Congo jute and sweet potato respectively when planted late. At 35 DAP, 
the 25th July and 12th August plantings were not significantly different from one 
another in stem diameter but were both significantly larger than the rest of the 
planting dates. Planting on 30th June, 12th July and 2nd August did not produce 
stems that were significantly different from one another, while both plantings in 
June and on 2nd August were also similar, but planting on 20thJune produced stems 
that were significantly different from those produced when planted on 12th July. 
At 42 DAP, plantings of 20th June, 25th July and 12th August produced stems that 
were significantly larger than each other but were all significantly larger than 
stems produced when planted 30th June, 12th July and 2nd August. Planting on 30th 
June and on 2nd August were similar to plantings of 30th June and on 12th July as 
they did not produce stems that were significantly different in each set, but 
planting on 2nd August produced stems that were significantly larger than those 
produced when planted on 12th July. At 49 DAP, while planting on 20th June, 25th 
July and 2nd August were not significantly different in stem diameter, planting on 
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30th June and on 12th July were also not significantly different. No significant 
difference was shown with both plantings in August too. However, planting on 
20th June, 25th July and on 2nd August produced stems that were significantly 
larger than stems produced when planted on both 30th June and 12th July. It is 
therefore necessary to look critically at the various varieties against planting dates 
that will produce thicker stems that are capable of supporting crop yield. Planting 
both Padi-Tuya and Zaayura on June 20th June and 25th July are appropriate 
varieties and planting dates that will produce thicker stems. 
  
5.1.1.3 Dry stem weight per plant 
Dry stem weight followed similar trend as for stem diameter. No significant 
interaction was observed but differences among the varieties, except during 
floweing, generally indicated Padi-Tuya and Zaayura produced bigger stems while 
Baawutawuta and Songotra produced smaller stem weights. Consistently, the 
varieties planted on 25th July produced bigger stems across all planting dates 
except Padi-Tuya at 49 DAP which produced the biggest dry stem weight with 
planting of 30th June. Baawutawuta in the first 42 DAP was again the variety that 
recorded the least dry stem weights while Padi-Tuya plants produced heaviest dry 
stems. Rajesh, (2010) also reported significant increase in vegetative characters in 
his study on Glycine max and Phaseolus mungo. At 35 DAP, the 30th June, 12th 
July and 25th July plantings were not significantly different from one another in 
stem dry weight per plant but both plantings on 30th June and 25th July produced 
stems that were significantly different from plantings of 20th June and both 
plantings in August. Planting on 12th July was similar in stem dry weight per plant 
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to planting on 20th June and 2nd August but significantly different from planting on 
12th August. At 42 DAP, the planting on 25th July produced stems that were 
significantly heavier than those produced when planted on all the other dates. 
Except with the planting of 30thJune that was also significantly different from the 
planting of 2nd August, the other planting dates produced stems that were not 
significantly different from one another. At 49 DAP, the first four dates planted 
were not significantly different from one another in stem dry weight per plant but 
were all significantly bigger than stems produced when planted on 2nd August, 
while both plantings of 30th June and 25th July were also significantly different 
from stems produced when planted on 12th August. The results generally reveals 
that bigger stem dry weights are achieved when planting of the cowpea varieties is 
done at the end of June (30th June) to the fourth week of July (25th July); and so 
such dates should be considered when dry matter production, as an added benefit, 
is conceived. 
 
5.1.1.4 Number of Branches from Main Stem 
Interaction effect between planting date and varieties was not significantly 
affected at 35, 42 and 49 DAP when number of branches from the main stem was 
considered. There were however, significant differences among varieties and this 
was recorded only at flowering. Reports by Babatunde et al., (2002) and Osei-
Kwateng et al., (2012) both confirm significant differences in number of branches 
observed among varieties of roselle.  The significant differences recorded in the 
number of branches of the cowpea varieties may be attributed to inherent variety 
characteristics or their genetic make-up. At flowering (42 DAP) Baawutawuta, 
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Baawutawuta, Padi-Tuya and Zaayura did not show significant differences among 
themselves, while Songotra and Zaayura were not also significantly different in 
number of branches on main stem, but Songotra showed significantly higher 
number of branches than both Baawutawuta and Padi-Tuya. Zaayura in this study 
appears to be a poor branching variety while Baawutawuta had more branches 
especially at maturity and also with shorter internodes which have contributed to 
the low heights of that variety. Significant differences in planting date with 
regards to branches on main stem was also recorded at flowering only and the 
means suggest that planting at the end of June produced the highest number of 
branches. There was no significant difference in the number of branches among 
plantings on 20th June, 12th July, 25th July and 2nd August but all were significantly 
different from planting on 12th August. 
 
5.1.1.5 Number of leaves per plant 
Interaction effects between planting dates and the four varieties was not 
significant in the number of leaves per plant. However, as individual factors, 
planting dates were significantly different among treatments with planting on 25th 
July significantly outstanding. At 35 DAP except planting on 12th July, planting 
on 25th July resulted in significantly higher number of leaves per plant than the 
rest of the dates (Table 12). Planting on 30th June, 12th July and 2nd August were 
not significantly different while planting on 20th June, 30th June, 12th July and 2nd 
August were also similar. Planting on 20th June and 12th August were also not 
significantly different but planting on 12th July produced leaf numbers that were 
significantly different from those obtained with the planting of both 20th June and 
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12th August. Also at 35 DAP, planting very early in August produced leaf 
numbers that were significantly different from planting on 12th August. At 42 
DAP, planting on 30th June, 12th July, 25th July and 12th August did not show 
significant differences in leaf numbers per plant but were all significantly different 
from both plantings on 20th June and 2nd August, while planting on 20th June and 
on 2nd August were not significantly different in leaf numbers (Table 13). At first 
harvest (49 DAP), planting on 12th July produced leaf numbers that were not 
significantly different from leaves per plant produced from planting of 30th June, 
and planting on 20th June, 30 June and 25th July were not also significantly 
different, but both plantings in June were significantly different from planting on 
2nd August. Planting on 30th June was also significantly different from planting on 
12th August. 
 
Considering the varieties involved in the experiment, except at first harvest, 
significant cowpea varietal differences occurred as was reported by Osei-Kwateng 
et al, (2012) on roselle. The varieties Baawutwuta and Padi-Tuya possibly by their 
genetic make-up (Wien and Summerfield, 1984) significantly produced more 
leaves than Songotra and Zaayura at 35DAP and at 42DAP. Songotra produced 
significantly lower number of leaves than the other three varieties (Table 12 & 
13). There was no significant difference in the number of leaves per plant among 
the varieties at 42 DAP (Table 14) and this suggests that Songotra and Zaaayura 
progressively increased in number of leaves with age and that Baawutawuta and 
Padi-Tuya produced more leaves at early growth stage (35 DAP) when planted on 
25th July. Production of leaves from the varieties could contribute to the 
production of a lot of biomass that can be harvested for animal feeding or 
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incorporated to improve the soil. There was a positive relationship (r = 0.056) 
between number of leaves and plant height (Table 36) which shows that increase 
in plant height resulted in increase in number of leaves. 
 
5.1.1.6 Leaf Area 
Significant differences in leaf area were recorded with planting date, varieties and 
even their interaction effects. The findings are in agreement with Muoneke et al. 
(2002) who reported significant leaf area on a roselle and cowpea intercrop, and 
Sreelatha et al. (1997) and Begum et al. (2003) who both found significant 
differences in leaf area in French beans. With the exception of Baawutawuta, 
planting of the varieties on 25th July generally produced significantly larger leaves 
than the other dates planted. Padi-Tuya produced leaves significantly larger than 
the other varieties. Padi-Tuya, even though was not significantly different from 
the other varieties in leaf number especially at first harvest (7 WAP), yet it 
recorded significantly higher leaf dry weight. This result might have been 
influenced by the large leaf area that the variety registered and that may have 
influenced the plants’ photosynthetic activity and therefore growth and yield. Leaf 
area also correlated positively (r = 0.190* and r = 0.481**) with number of pods 
per plant and stem diameter at first harvest (Table 36). 
 
5.1.1.7 Plant canopy 
Except for varieties there was no significant difference observed on plant canopy 
(Table 23). Songotra produced significantly smaller canopy as compared with the 
other varieties and this might have contributed to the significant difference among 
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varieties in weight of biomass per plot (Table 21). There was no significant 
difference in plant canopy among Baawutawuta, Padi-Tuya and Zaayura. Results 
of correlation analysis of some of the parameters (Table 36), revealed that there 
was positive correlation between plant canopy and stem diameter at first harvest (r 
= 0.290*), number of leaves at first harvest (r = 0.251*) and number of pods per 
plant (r = 0.350**). 
 
5.1.1.8 Dry weight of leaves per plant 
The interaction planting date and variety was not significant at all the stages of 
plant growth. Padi-Tuya produced the highest dry leaf weight per plant (Tables 15 
& 16). Baawutawuta also significantly out yielded Zaayura in leaf dry weight per 
plant while Songotra and Zaayura were not different at 42 DAP. Baawutawuta, 
Songotra and Zaayura did not record significant differences among them in leaf 
dry weight at first harvest.  
 
At flowering stage (42 DAP), planting in July and especially the fourth planting 
date (25thJuly) gave best results as it produced significantly higher leaf dry weight 
than the other planting dates. While significant differences were not found among 
planting on 20th June, 30th June, 12th July and 12th August, and also among 
planting on 20th June and 2nd August, planting on 2nd August also significantly 
produced lower dry leaf weights per plant than planting on 30th June, 12th July and 
12th August. Planting on 12th July was not significantly different from planting on 
30th June but yielded significantly higher leaf dry weight per plant at the first 
harvest stage than the other dates planted (Table 16). While planting on 20th June, 
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30th June, 25th July 12th August did not produce significantly different results, 
planting on 30th June significantly out-yielded planting on 2nd August in leaf dry 
weight. This is in agreement with reports by Osei-Kwateng et al, (2012) and 
Addo-Quaye, (2011a) that dry matter of roselle and cowpea respectively to be 
significantly high. 
 
5.1.1.9 Dry weight of roots per plant 
There was no significant interaction between planting date and varieties on dry 
weight of roots per plant at the different stages of plant growth that this parameter 
was determined (35, 42, & 49 DAP). Root dry weight Padi-Tuya was significantly 
higher than those of the other varieties (Tables 19 & 20). From visual observation 
on the field, this variety actually never showed any sign of lodging during the 
growing period and could be good for planting on windy sites. Root dry weight at 
flowering showed that planting on 25th July produced results that were 
significantly different from the other planting dates. There were no significant 
differences among plantings on 12th July and 12th August, 12th July and 2nd 
August, and 20th June and 2nd August respectively, but planting on 12th July and 
12th August significantly out-yielded both plantings in June. Planting on 20th June 
and on 2nd August also significantly produced higher root dry weight than planting 
on 30th June at 42 DAP. At first harvest (49 DAP), planting on 12th July and on 
25th July were not significantly different from one another but were both 
significantly different from the other planting dates and therefore the appropriate 
dates of planting if good root establishment is to be achieved. Planting 20th June, 
30th June and 2nd August did not produce significant differences among them, but 
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planting on 20th June was significantly different from planting on 12th August. 
Results at first harvest (49 DAP) further indicated that lower root dry weight were 
achieved with planting too early (June) and too late (August). 
 
5.1.1.10 Dry biomass weight per plot 
There were no significant differences in planting dates and also interaction 
between planting date and varieties. This is not in agreement with reports by 
Rutkowski and Fordonski (1987) and Kurmawanshi et al. (1994) in experiments 
conducted on field bean (Vicia faba), and Sreelatha et al. (1997) on French beans, 
who concluded that early sowing resulted in significantly higher biomass yield 
compared to late sowing. Padi-Tuya produced significantly higher dry biomass 
than Songotra and Zaayura but was similar to Baawutawuta. Baawutawuta also 
produced dry biomass that was significantly higher than Songotra. It therefore 
stands that Padi-Tuya and Baawutawuta, apart from yield can be grown by 
farmers for their additional benefit depending on farmers’ choice. Additional 
benefits include working biomass back into the soil to increase its organic matter 
content and therefore improving soil fertility and water holding capacity, and also 
animal farmers can have the plenty dry biomass to feed their animals during the 
dry season when animal feed is scarce. 
 
5.1.1.11 Days to first flower appearance 
There was no significant planting date by variety interaction but it was observed 
that for all the varieties, earliest first flowers appeared with planting on 25th July. 
Songotra was the variety that produced the earliest first flower across all dates 
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planted while Baawutawuta was the latest to produce flowers. There was no 
significant difference between Songotra and Zaayura but they both had 
significantly less number of days to first flowers than both Baawutawuta and Padi-
Tuya. Baawutawuta also produced first flowers significantly later than Padi-Tuya. 
The difference among the varieties on days to first flower appearance might be 
due to the varietal character. This is supported by Nsowah, (1970) who reported 
that planting dates did not influence floral initiation and opening in egg-plants, 
and Norman, (1981) who reported that flowering and fruit maturity in pineapple 
was not significantly affected by planting date. Early flowering varieties of 
cowpea such as Songotra can escape drought in an area such as this experimental 
area which mostly has few months of erratic rainfall. This agrees with the report 
of Ismail et al., (1997) that early flowering cowpeas can escape drought and 
produce high yields. Yama, (2006) disagrees with this in his report that a cowpea 
variety was earliest to flower but produced the smallest and shortest pods and 
consequently the lowest yield. Planting on 25th July was different from all other 
dates as significantly fewer numbers of days to first flower was observed with 
planting on this date than all the other dates planted. All other dates planted did 
not show significant differences in number of days to first flower. 
 
5.1.1.12 Days to 50% flowering 
Planting dates, varieties of cowpea and also their interaction between planting date 
and variety showed significant differences when days to 50% flowering was 
recorded. Planting any of the four varieties on 25th July emerged best if early 
flowering is to be achieved. Baawutawuta planted on 25th July recorded 
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significantly less number of days to 50% flowering than planting on 30th June, 12th 
July and 2nd August but there were no significant differences with planting the 
variety on all the other dates. With Padi-Tuya, planting on 25th July recorded 
significantly less number of days to 50% flowering than planting on both 30th June 
and 12th August. Apart from 25th July, planting on 2nd August resulted in 
significantly higher number of days to 50% flowering than the rest of the dates, 
meanwhile there was no significant differences among the other dates. Songotra 
when planted on 25th July took significantly fewer days to 50% flowering than 
planting it on 20th June, 30th June, 12th July and 2nd August but not with planting it 
on 12th August. Planting of Songotra in June, 12th July and 2nd August did not 
register significant differences among them.  
 
Planting Zaayura on the first three planting dates (20th June, 30th June and 12th 
July) did not show significant differences among them but all registered 
significantly higher number of days to 50% flowering than planting it on the later 
three planting dates (25th July, 2nd August and 12th August). The significant 
difference among varieties is in agreement with the report by Obadoni, (2009) that 
significant differences in the number of days to 50% flowering among cowpea 
varieties. In contrast to this finding, Nsowah, (1970) reported non-significant 
effects of planting date on flowering in egg-plants, whiles in another study, 
Norman (1981) reported of planting date not significantly affecting flowering and 
fruit maturity of pineapple.  Wallace et al. (1995) and Husain et al., (1988) 
reported that temperature is undoubtedly the dominant factor, which affects 
flowering and maturity in field beans and navy beans respectively, while Marfo 
and Hall (1992) suggested that floral bud development is inhibited by the 
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combination of high temperatures and long days that finally result in few flowers 
produced. Songotra was the variety that was ealiest to reach 50% flowering in the 
study and should be first to select if early flowering is the objective and 
considering that early flowering is a good characteristic in locations like Upper 
East Region of Ghana where the rainfall pattern is short and erratic. 
 
5.1.1.13 Days to first pod set 
Number of days to first pod set followed the same trend as for days to first flower 
in that, there was no significant difference in the interaction between planting date 
and varieties and that planting on 25th July was more appropriate as planting on 
this date produced earliest pods as compared with the other planting dates. 
Significantly less number of days to first pod set was recorded when planting was 
done on 25th July than all the other planting dates. With the exception of planting 
on 25th July, planting on 20th June was significantly different from the rest of the 
planting dates, while the rest of the planting dates (30th June, 12th July, 2nd August 
and 12th August) did not differ from each other significantly. Songotra and 
Zaayura did not show significant difference among them but both reached 50% 
flowering at significantly lesser number of days than both Baawutawuta and Padi-
Tuya and therefore were earliest pod setters and could be chosen if earliest pod 
setting is a priority and seed yield is envisaged.  
 
5.1.1.14 Days to first harvest 
Significant differences were observed among planting dates, cowpea varieties and 
also the interaction between planting dates and cowpea varieties when days to first 
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harvest from planting was studied. All varieties responded significantly to 
planting on 30th June by taking fewer numbers of days to first harvest. The 
difference in harvesting days of the varieties was most likely due to the varietal 
differences as has been observed that species of various crops have adaptive 
features that contribute to timely flowering (Wien and Summerfield, 1984) and 
subsequent yield and harvesting. Earliness plays an important role when it comes 
to mitigating hunger, meeting market demand and fetching higher market price 
and more income. Songotra which was the first to flower was equally first to be 
harvested and planting on the 30th June was also significantly different from the 
other planting dates. Songotra which flowered earlier matured earlier and was the 
first to be harvested but did not significantly out-yield the other varieties. This 
contradicts the findings of Yama, (2006) that a variety that was earliest to flower, 
and harvested first, produced the smallest and shortest pods and subsequently the 
lowest yield. 
 
5.1.2 Crop Yield 
5.1.2.1 Pod number per plot 
The response of number of pods to the interaction between planting date and 
cowpea varieties was not significant. However the varieties in themselves 
produced varying numbers of pods which were significantly different among 
them. Possibly by their inherent genetic make-up, Baawutawuta produced 
significantly more pods than the other three varieties but there were no significant 
differences recorded among Padi-Tuya, Songotra and Zaayura though Songotra 
produced the lowest number of pods per plant. Planting dates actually did not 
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produce any significant effect on pod yield. This is in contradiction to the report 
by Nsowah, (1970) when he studied sowing dates on egg-plant varieties in which 
number of fruits were significantly different. 
 
5.1.2.2 Number of pods per plant 
There was no significant interaction between planting date and cowpea varieties. 
Also planting dates did not produce any significant difference as inconsistent and 
fluctuating numbers of pods per plant were obtained with the different dates. 
However, differences among varieties with regards to planting were significant 
with Baawutawuta being significantly different from all the varieties as it 
produced the highest pod number per plant. Padi-Tuya was similar to Zaayura but 
also produced significantly higher number of pods per plant than Songotra. The 
difference between Songotra and Zaayura was also not significant. Though 
Adcock, (1976) reported that most often four pods are carried on peduncles of 
Vicia faba, the cowpea varieties produced varying numbers of pods per plant 
ranging from 8 to 14. Iremiren and Akly, (1986), Yadev, (1999) and Incalcaterra 
et al., (2000) reported of higher number of fruits per plant on early sown okra than 
late sown. If pod-setting ability is to be used in the determination of overall yield, 
Baawutawuta was the best in this study. There was a negative correlation (r = - 
0.109) between number of pods per plant and mean pod weight which does not 
agree with reports by Kambal, (1969); Ishag, (1973); and Husain et al. (1988) in 
their studies of Vicia faba L., that there was not only consistent but also strong 
correlation between the number of pods per plant and yield. 
 
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5.1.2.3 Weight of pods per hectare 
Pod weight is a major parameter that is used to estimate yield and therefore it was 
measured on per plot basis so that other projections could be made if necessary. 
Planting dates and cowpea varieties even as independent factors were not 
significantly different and so was the interaction effect of the factors. Pods of 
Padi-Tuya had higher mean weight than the others they were not significantly 
different from each other. The variety, Zaayura recorded the lowest mean pod 
weight. The result suggests that pod weight was similar among the varieties even 
when planted on different dates as reported by CSIR – SARI (2008) in their 
variety release of cowpeas publication that all four varieties have comparable 
yields. This lack of significant difference in yield however does not agree with the 
reports by Dhital et al. (1998) which showed that planting date influenced yield of 
cowpea and that early planting produced higher yield than late planting. Nsowah, 
(1970) also reported that early planting produced higher fruit weight of egg-plant 
than late planting while reports of both Iremiren and Akly (1986) and Sayeed, 
(1988) indicated that okro pod yield was highest with early sowing as compared to 
late planting. 
 
5.1.2.4 Weight of pods per plant 
Weight of pods per plant showed significant differences only for varieties with 
Padi-Tuya being significantly higher than the other varieties though among the 
other three varieties there was no significant differences in weight. Zaayura 
recorded the lowest weight of pods per plant. Though planting date did not show 
any significant difference for weight of pods per plant, the earliest planting date 
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(20th June) recorded the highest weight and planting on 25th July recorded the 
lowest weight of pods per plant.  
 
5.1.2.5 Mean pod weight 
Considering weights of individual pods (mean pod weight) there were significant 
differences among planting dates, varieties and also with their interaction. The 
results from mean pod weight confirms reports of Dhital et al., (1998), Nsowah, 
(1970) and both Iremiren and Akly, (1986) and Sayeed, (1988) who worked on 
cowpea, egg-plant and okro respectively. Significantly higher pod weight of 
Baawutawuta was recorded with the planting on June 20ththan planting on June 
30th only. Any other date planted to Baawutawuta was not significantly different 
from each other. With the exception of planting on June 30th, planting Padi-Tuya 
on 20th June produced significantly higher pod weight than all other dates it was 
planted. Padi-Tuya planted on 30th June was not significantly different from 
planting it on 12th July, but was significantly different from the last three dates 
which among themselves were similar. Except with the planting of 25th July, 
Songotra planted on 20th June produced significantly higher pod weight than all 
dates it was planted. Also planting on 25th July for Songotra produced 
significantly higher pod weight than planting on 12th August, while there was no 
significant difference among the other dates planted to Songotra. Zaayura deviated 
from the other varieties because it produced significantly higher pod weight with 
the planting on 12th August than all the other dates that it was planted except with 
the planting on 2nd August. Zaayura planted on 20th June and on 2nd August were 
not significantly different from each other but were both significantly different 
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from planting on12th July. Significant differences were not recorded when 
Zaayura was planted on 30th June, 12th July and 25th July.  
 
5.1.2.6 Pod length 
Pod length did not show significant interaction between planting date and 
varieties. However, differences among the varieties and planting dates on pod 
length were significant. Pods of Padi-Tuya were significantly longer than the pods 
of the other three varieties, while significant differences in pod length were not 
recorded among the other three varieties. Longer pods were produced when 
planting was done on 20th June and 12th July; meanwhile they were not 
significantly different from one another. However, planting on 20th June produced 
significantly longer pods than on the other dates planted. Both plantings in July 
produced pod lengths that were similar but planting on 12th July produced 
significantly longer pods than plantings on 30th June and both planting dates in 
August. Planting of the cowpea varieties especially in the month of August 
yielded shortest pods and were not significantly different from one another. Pod 
length is one of the major criteria for selecting better variety for higher yield and 
preferable pod size, which is a preferred market appealing character, Padi-Tuya 
will best satisfy this purpose. Longer pods of cowpea contribute to more yield 
than shorter pods (Yama, 2006). Other workers who reported of significantly 
higher yields include Yadev, (1999) on okro, and Peksen, (2002) on cowpea. If for 
some reason any of the other varieties are to be planted, planting on 20th June and 
12th July will yield longer pods.  
 
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5.1.2.7 Pod diameter 
A larger pod is also a criterion for selecting better cowpea varieties that best suits 
the market and satisfy the consumer in addition to higher yields that may be 
achieved. It has been established that big pods of cowpea produce the highest 
green pod yield that has a potential of being recommended for commercial 
production (Yama, 2006). Highly significant differences were recorded with 
planting dates, cowpea varieties and the interaction of both factors. Pod diameter 
measurement of all the varieties showed significant difference when planted on 
12th August compared to the other planting dates. Planting on 12th and 25th July 
produced significantly smaller pods in diameter than the other dates but were not 
different from each other. Planting Baawutawuta, Padi-Tuya and Zaayura on 20th 
June, 30th June and 2nd August did not show significant differences in pod 
diameter, while Songotra planted on 2nd August was significantly different in pod 
diameter from both plantings of 20th June and 30th June, but both planting in June 
were not different. It is therefore evident that planting on 12th August produced 
larger pods while smaller pods were produced from both 12thand 25thJuly 
plantings.   
 
5.1.2.8 Number of seeds per pod 
Though pods were harvested before seeds were fully developed, seed numbers per 
pod were recorded which showed significant differences in planting dates, 
varieties and their interaction. Baawutawuta produced the highest number of seeds 
per pod while Zaayura produced the lowest number of seeds. Planting Songotra on 
25th July produced significantly higher number of seeds per pod than planting it on 
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2nd August. Zaayura planted on 12th August produced significantly higher number 
of seeds per pod than both plantings of 30th June and 12th July while planting it on 
20th June, 25th July and 2nd August produced significantly higher number of seeds 
than planting on 12th July. Significant seed numbers of varieties agree with reports 
by Razaq, (1995) who attributed differences in mung beans to genotype 
differences. Also Ahmad et al., (2001) observed that genotypic makeup of wheat 
varieties influence number of seeds per pod, and Board et al., (1999) assigned 
significant variations to some soyabean plants failing to develop pods. The 
findings of Dhital et al., (1998) that number of seeds per pod of cowpea varieties 
was influenced by planting dates of cowpea is similar to the current results, while 
Singh et al., (1986) reported that seed yields of okra was highest in early planted 
plots. 
 
The result confirms reports by Dantuma and Thompson, (1983) and Ishag, (1973) 
that the number of seeds per pod of fababean (Vicia faba L.) can vary 
considerably. However, the result contradicts that of Thompson and Taylor (1981) 
who reported that the number of seeds per pod had proved to be the most 
consistent component of yield. 
 
5.1.3 Fibre Content 
The interaction between planting date and cowpea varieties was significant.. 
Higher fibre content was recorded with planting in August while planting in July 
recorded the lowest. Baawutawuta and Padi-Tuya planted on 12th August 
produced significantly higher fibre content than planting on the other dates. 
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Planting Baawutawuta on 20th June and on 2nd August produced fibre content that 
was significantly different from fibre content produced when planted in July, 
while planting in June and 2nd August were not significantly different. With Padi-
Tuya, planting on all the other dates except planting on 12nd August, did not 
produce significant differences in fibre content. Songotra and Zaayura followed 
the same trend. Planting on 12th August produced significantly higher fibre than 
the other dates planted to them, but there were no significant differences recorded 
when planted on the other dates. Mean fibre content of the varieties suggests, in a 
descending order, that more fibre was contained in Baawutwuta, Zaayura, 
Songotra and Padi-Tuya. This indicates that the varieties contained varying 
amounts of fibre and therefore depending on the need the appropriate variety 
could be chosen. 
 
 
 
 
 
 
 
 
 
 
 
 
 
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CONCLUSIONS 
 
The interaction between planting date and varieties was not significant for most of 
the growth parameters, including stem diameter, stem dry weight, number of 
leaves, leaf dry weight, number of branches from the main stem and number of 
pods per plant  were determined. However, there were significant differences 
among planting dates and among varieties for these parameters showing that if 
any of the above parameters is considered as a main purpose then planting dates 
and or varieties which gave best results could be used.  
 
Padi-Tuya produced plants that were significantly taller than Baawutawuta, 
Songotra and Zaayura. Both Padi-Tuya and Zaayura produced significantly bigger 
stems than the Baawutawuta and Songotra. The stems of Padi-Tuya and Zaayura 
can support pods well above soil surface thereby avoiding soil contamination and 
planting on 25th July significantly influenced the results.  
 
Baawutawuta produced more leaves than Padi-Tuya, Songotra and Zaayura, while 
Padi-Tuya produced larger leaves than the other three varieties and with both 
parameters, planting on 25th July yielded the best results. 
 
Earliest flowering and harvesting was associated with Songotra as compared to 
Baawutawuta, Pad-Tuya and Zaayura and planting on 25th July induced the 
earliest flowering while planting on 30th June was associated with earliest harvest.  
 
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All four varieties involved in this study performed differently in terms of yield 
and yield components across planting dates and are good materials for green pod 
production and again, planting date is an important factor to be considered when 
selecting varieties for specific productions. From this study, planting on 25th July 
posed to be most appropriate. 
 
Both mean green pod number and number of seeds per pod revealed significant 
interaction between planting dates and varieties. Padi-Tuya produced highest 
mean pod weight while Baawutawuta produced pods with greater number of 
seeds.  
 
Generally, the results indicate that pod size (length and diameter) and number of 
seeds in pods are major determining factors for yield estimation in that, the bigger 
the pods and or the more the number of seeds in pods, the higher the yield. This 
might have accounted for the yield similarity of the Zaayura and Baawutawuta 
varieties since Zaayura produced bigger green pods and also recorded less seeds in 
pods than Baawutawuta and vice versa but their green pod yields were similar. 
 
Longest pods and largest pods were produced by Padi-Tuya and Zaayura 
respectively and planting on 20th June produced the longest pods while the largest 
pods were produced with the planting on 12th August. 
 
The results indicate that there were varying levels of fibre in the green pods of the 
cowpea varieties and that Baawutawuta registered the highest amount of fibre 
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while Padi-Tuya recorded the lowest. Planting in the month of August produced 
the highest fibre content. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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RECOMMENDATIONS 
 
Based on the results of the experiment the following recommendations are made: 
 
This current study should be considered as preliminary as results are reported 
using one year data; so my recommendation is that further studies involving more 
varieties, and in different seasons and locations should be done, and if the findings 
are confirmed, then such varieties are recommended for commercial production of 
green pods.  
 
Songotra should be grown in locations that have short periods of rainfall since 
they bloom earliest and therefore will pod early. 
 
Plant and pod sizes of Padi-Tuya and Zaayura are significantly bigger and 
growing these varieties especially in areas of strong winds and continuously moist 
soils should be encouraged as their large stems can support many and heavy pods, 
while pods still carried high above ground level to avoid soil contact.  
 
Early planting should be recommended as favourable weather conditions and less 
insect attacks could be advantageous. 
 
 
 
 
 
 
 
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