EFFECT OF ORGANIC MULCH ON GROWTH AND YIELD OF SWEET PEPPER (Capsicum annuum L) BY ADDO NORVIS KOMLA (10362732) THIS THESIS IS SUBMITTED TO THE UNIVERSITY OF GHANA, LEGON IN PARTIAL FULFILLMENT OF THE REQUIREMENT FOR THE AWARD OF MPHIL CROP SCIENCE DEGREE. CROP SCIENCE DEPARTMENT UNIVERSITY OF GHANA LEGON JULY, 2013 University of Ghana http://ugspace.ug.edu.gh i DECLARATION In exception of references to the works of researchers which have been duly cited, this thesis is the result of my own work produced from research undertaken under supervision. ………………………… Addo Norvis Komla (Student) …………………. (Date) …………………………… Prof. J.C. Norman (Principal Supervisor) ………………… (Date) ………………………… Prof. S. Adjei - Nsiah (Co-supervisor) ………………… (Date) University of Ghana http://ugspace.ug.edu.gh ii ACKNOWLEGEMENTS Without the support, guidance and encouragement of my supervisors, family and friends this thesis could not have been accomplished. I therefore express my sincerest appreciation to Prof. J.C. Norman and Dr. Adjei – Nsiah for their guidance, useful suggestions and contributions. I express my profound gratitude to my wife Mrs. Gifty Opare Addo and my mother Mrs. Patience Foli Addo for financial support and prayers throughout my studies. I also express my profound gratitude to my friends Sylvester Ampiah, David Martei and Christian Boahen Obeng for their support in diverse ways. I also thank all the staff and people of Forest and Horticultural Crops Research Centre (FOHCREC), Kade for their pieces of advice and support. Glory be to God for His faithfulness, mercy, guidance and protection offered me throughout my graduate studies. University of Ghana http://ugspace.ug.edu.gh iii DEDICATION I dedicate this thesis to my wife Mrs. Gifty Opare Addo, my mother Mrs. Patience Foli Addo, my grandfather Mr. Richmond Komla Mawuena Foli and my grandmother Mrs. Monica Yaodem Foli. University of Ghana http://ugspace.ug.edu.gh iv ABSTRACT The high cost and increasing disposal problems associated with polyethylene mulch and greater availability of organic mulches prompted an investigation into the effects of organic mulches on growth and yield of sweet pepper at the University of Ghana Forest and Horticultural Crops Research Centre, Okumaning near Kade. Two field experiments were conducted in the raining season, that is from July, 2012 to December, 2012 and in the dry season from December, 2012 to March, 2013. In both experiments four treatments; dry rice husks (RH), empty palm fruit bunches (EPFB) and cocoa pods husks (CPH) as mulches at the rate of 35t/ha each and a control (bare soil) were evaluated in a randomized complete block design with four replications. The results indicated that organic mulch application in both rainy and dry seasons significantly influenced soil temperature and suppressed weed growth. Soil moisture content was not significantly influenced by the mulch materials in the rainy season. However, in the dry season soils under mulched plots retained significant amount of soil moisture compared to soils under no mulch treatment. Organic mulch application in the rainy season did not significantly increase plant height, stem diameter, number of branches, number of leaves, leaf area as well as leaf area index of sweet pepper compared to the control. However, the application of organic mulch compared to the control resulted in increased plant height, canopy size and stem diameter in the dry season. Although weight of fruits per plant, mean fruit weight per plant, total fruit yield, fruit length and fruit width were not significantly increased by the application of organic mulch materials in the rainy season, mulching significantly influenced yield and yield components of sweet pepper in the dry season. Application of rice husk mulch was the most effective treatment in increasing the weight of fruits per plant, total fruit yield and mean fruit weight per plant. University of Ghana http://ugspace.ug.edu.gh v TABLE OF CONTENTS DECLARATION .................................................................................................................... i ACKNOWLEGEMENTS ..................................................................................................... ii DEDICATION .................................................................................................................... iii ABSTRACT ......................................................................................................................... iv TABLE OF CONTENTS ...................................................................................................... v LIST OF TABLES ............................................................................................................... ix CHAPTER ONE .................................................................................................................... 1 INTRODUCTION ................................................................................................................. 1 1.1 Problem Statement ........................................................................................................... 2 1.2 Objectives ........................................................................................................................ 4 CHAPTER TWO ................................................................................................................... 5 LITERATURE REVIEW ...................................................................................................... 5 2.1 Climatic requirements of sweet pepper ........................................................................... 5 2.2. Soil requirements of sweet pepper ................................................................................. 6 2.3 Use of mulches in vegetable production.......................................................................... 6 2.4 Types of mulches ............................................................................................................. 8 2.5 Effect of organic mulches on soil moisture. .................................................................... 9 2.5.1 Effect of organic mulches on soil temperature ....................................................... 10 2.5.2 Effect of organic mulches on weed control. ........................................................... 10 2.5.3: Effect of organic mulches on plant growth. ........................................................... 11 2.5.3.1 Leaf area ........................................................................................................... 11 2.5.3.2 Number of leaves per plant .............................................................................. 11 2.5.3.3 Number of branches ......................................................................................... 12 2.5.3.4 Plant height ....................................................................................................... 12 2.5.3.5 Canopy width ................................................................................................... 13 2.5.3.6 Stem diameter ................................................................................................... 14 2.5.3.7 Plant dry matter ................................................................................................ 14 2.5.4 Effect of organic mulches on flowering and harvesting ......................................... 14 2.5.4.1 Number of days to flower................................................................................. 14 2.5.4.2 Number of days to fruit set ............................................................................... 15 2.5.4.3 Number of days to first fruit harvest ................................................................ 15 2.5.5: Effect of organic mulches on plant yield ............................................................... 15 University of Ghana http://ugspace.ug.edu.gh vi 2.5.5.1 Mean fruit weight ............................................................................................. 15 2.5.5.3 Number of fruit per plant ................................................................................. 16 2.5.5.4 Yield per hectare .............................................................................................. 17 2.5.6 Effect of organic mulches on fruit quality .............................................................. 19 2.5.6.1 Fruit length ....................................................................................................... 19 2.5.6.2 Fruit width ........................................................................................................ 19 2.5.7 Effect of organic mulches on net return .................................................................. 19 CHAPTER THREE ............................................................................................................. 20 MATERIALS AND METHODS ........................................................................................ 20 3.1 Experimental site ........................................................................................................... 20 3.2 Soil characteristics of the experimental site .................................................................. 21 3.3 Experimental details ...................................................................................................... 22 3.4 Cultural practices ........................................................................................................... 22 3.4.1 Land preparation ..................................................................................................... 22 3.4.2 Raising of nursery ................................................................................................... 23 3.4.3 Sowing of seeds and after care ............................................................................... 23 3.4.4 Transplanting .......................................................................................................... 23 3.4.5 Application of manures and fertilizers .................................................................... 23 3.4.6 Irrigation ................................................................................................................. 23 3.4.7 Crop protection measures ....................................................................................... 24 3.5 Data collection ............................................................................................................... 24 3.5.1 Growth parameters .................................................................................................. 24 3.5.1.1 Plant height ....................................................................................................... 24 3.5.1.3 Number of branches per plant .......................................................................... 25 3.5.1.4 Number of leaves per plant .............................................................................. 25 3.5.1.5 Leaf area per plant ............................................................................................ 25 3.5.1.6 Leaf area index (LAI) ....................................................................................... 25 3.5.1.7 Dry matter production and its accumulation in different plant parts ............... 25 3.5.1.8 Plant canopy ..................................................................................................... 26 3.5.1.9 Days to 50 per cent flowering .......................................................................... 26 3.5.1.10 Days to first fruit set ....................................................................................... 26 3.5.1.11 Days to 50 per cent fruit set ........................................................................... 26 3.5.1.12 Days to final fruit harvest ............................................................................... 26 3.5.2 Yield parameters ..................................................................................................... 26 University of Ghana http://ugspace.ug.edu.gh vii 3.5.2.1 Number of fruits per plant ................................................................................ 27 3.5.2.2 Fruits weight per plant...................................................................................... 27 3.5.2.3 Weight of fruits per hectare .............................................................................. 27 3.5.2.4 Fruit length ....................................................................................................... 27 3.5.2.5 Fruit width ........................................................................................................ 27 3.5.2.6 Marketable and unmarketable fruits ................................................................. 27 3.5.3 Soil parameters ....................................................................................................... 28 3.5.3.1 Soil moisture content ........................................................................................ 28 3.5.4 Weed parameter ...................................................................................................... 28 3.5.4.1 Weed biomass .................................................................................................. 28 3.5. 5 Disease assessment ................................................................................................ 29 3.5.5.1 Assessment of severity of Capsicum chlorosis disease (CaCD) ...................... 29 3.5.6 Economic analysis .................................................................................................. 29 3.6 Data analysis .................................................................................................................. 30 CHAPTER FOUR ............................................................................................................... 31 RESULTS ............................................................................................................................ 31 4.1 Effect of organic mulch on vegetative growth of sweet pepper at 50% flowering. ...... 31 4.2 Mean and total dry shoot biomass ................................................................................. 32 4.3 Phenology ...................................................................................................................... 34 4.4 Fruit set .......................................................................................................................... 35 4.5 Days to final fruit harvest and cropping period ............................................................. 35 4.6 Yield and yield components. ......................................................................................... 36 4.7 Mean number and weight of marketable and unmarketable fruits ................................ 37 4.8 Soil moisture content ..................................................................................................... 39 4.9 Effect of organic mulch on soil temperature ................................................................. 40 4.10 Weed biomass .............................................................................................................. 40 4.11 Disease assessment ...................................................................................................... 41 Table 16: Matrix of correlation (r) among some soil and growth and yield parameters of green pepper in the dry season ............................................................................................ 47 4.13 Economic analysis of using organic mulches (rice husk, empty palm fruit bunch and cocoa pod husk) and bare soil for sweet pepper production................................................ 48 4.14 Economic analysis of using organic mulches (rice husk, empty palm fruit bunch and cocoa pod husk) and bare soil for sweet pepper production................................................ 49 University of Ghana http://ugspace.ug.edu.gh viii CHAPTER FIVE ................................................................................................................. 55 DISCUSSION ...................................................................................................................... 55 5.1 Effect of organic mulch on soil temperature and moisture content ............................... 55 5.2 Effect of organic mulch on Weed biomass .................................................................... 55 5.3 Growth and Yield .......................................................................................................... 55 5.4 Capsicum Chlorosis disease assessment........................................................................ 59 5.5 Profitability of the different types of organic mulches and bare soil on sweet pepper production ............................................................................................................................ 60 CONCLUSION AND RECOMMENDATION .................................................................. 61 6.1 Conclusion ..................................................................................................................... 61 6.2 Recommendation ........................................................................................................... 61 REFERENCES .................................................................................................................... 62 APPENDICES ..................................................................................................................... 71 Appendix 1: Catalogue of production cost (GHC) in sweet pepper grown under different organic mulches in the raining season ................................................................................. 71 Appendix 2: Catalogue of production cost (GHC) in sweet pepper grown under different organic mulches in the dry season ....................................................................................... 72 University of Ghana http://ugspace.ug.edu.gh ix LIST OF TABLES Table 3.1: Climatic data during the experimental period .................................................... 21 Table 3.2 Initial soil chemical and physical properties from the experimental site.............22 Table 3.3: severity rating for CaCD.....................................................................................29 Table 1: Effect of organic mulch on vegetative growth parameters of sweet pepper at 50% flowering in the raining season............................................................................................32 Table 2: Effect of organic mulch on vegetative growth parameters of sweet pepper at 50% flowering in the dry season..................................................................................................32 Table 3: Effect of organic mulch on vegetative growth (mean and total dry shoot biomass) of sweet pepper at 3 WAT in the raining season.................................................................33 Table 4: Effect of organic mulch on vegetative growth (mean and total dry shoot biomass) of sweet pepper at harvesting in the dry season...................................................................33 Table 6: Effect of organic mulch on number of days to first and 50% fruit set of sweet pepper in the dry season ...................................................................................................... 34 Table 7: Effect of organic mulch on the number of days to final fruit harvest and period of harvest of sweet pepper in the dry season ........................................................................... 35 Table 8: Effect of organic mulch on yield and yield components of sweet pepper in the raining season ...................................................................................................................... 36 Table 9: Effect of organic mulch on the yield and yield components of sweet pepper in the dry season ............................................................................................................................ 37 Table 10: Effect of organic much on mean number and weight of marketable fruits and mean number and weight of unmarketable fruits of sweet pepper in the raining season .... 37 Table 11: Effect of organic much on mean number and weight of marketable fruits and mean number and weight of unmarketable fruits of sweet pepper in the dry season .......... 39 Table12: Effect of organic mulch on soil moisture content, temperature, and fresh weed biomass in the raining season .............................................................................................. 39 Table 13: Effect of organic mulch on soil moisture content, temperature, and fresh weed biomass in the dry season .................................................................................................... 41 Table 14: Effect of organic mulch on severity of Capsicum chlorosis disease on sweet pepper in dry season ............................................................................................................ 41 Table 15: Matrix of correlation (r) among some soil and growth and yield parameters of green pepper in the raining season ...................................................................................... 42 Table 16: Matrix of correlation (r) among some soil and growth and yield parameters of green pepper in the dry season...................................................................... ....................46 Table 17: Estimated cost of production, gross revenue and return on investment of sweet pepper grown under different organic mulches when the vegetable was retailed in the city in the raining season ............................................................................................................ 47 University of Ghana http://ugspace.ug.edu.gh x Table 18: Estimated cost of production, gross revenue and return on investment of sweet pepper grown under different organic mulches when the vegetable was sold at the farm gate in the raining season..................................................................................................... 50 Table 19: Estimated cost of production, gross revenue and return on investment of sweet pepper grown under different organic mulches when the vegetable was retailed in the city in the dry season .................................................................................................................. 51 Table 20: Estimated cost of production, gross revenue and return on investment of sweet pepper grown under different organic mulches when the vegetable was sold at the farm gate in the dry season........................................................................................................... 53 University of Ghana http://ugspace.ug.edu.gh xi LIST OF PLATES Plate 1: plant infested with Capsicum chlorosis disease (CacD) …………………….42 Plate 2: fruits from plant infested with Capsicum chlorosis disease (CacD)……… ..42 University of Ghana http://ugspace.ug.edu.gh 1 CHAPTER ONE INTRODUCTION Sweet pepper (Capsicum annuum L.) belongs to the family Solanaceae. It is an important vegetable cum condiment and an active ingredient in cookery. The sweet pepper fruit is rich source of vitamins, especially vitamin A, C and E. It also contains thiamine, vitamin B6, beta carotene, and folic acid. It is grown for green, spices, condiments, sauces and pickles. It also imparts peculiar beauty, taste and flavour to cook the vegetables and other dishes (Tarara, 2000). Sweet pepper has gained popularity probably due to its additional importance as it also contains a large amount of phytochemicals that have exceptional antioxidant activity, and the production and consumption thereof has increased worldwide. These phytochemicals include chlorogenic acid, zeaxanthin, and coumeric acid. Possibly due to the vitamin C and beta carotene content, green peppers have been shown to be protective against cataracts. They have also been shown to prevent blood clot formation and reduce the risk of heart attacks and strokes probably due to their content of substances such as vitamin C, capsaicin, and flavonoids. Although chilli peppers contain a higher amount of vitamin C, capsaicin, and flavonoids, sweet peppers should still be promoted especially for individuals with elevated cholesterol levels (Murray, 2005). In Ghana, sweet peppers are grown for both local consumption and export. It is now being cultivated commercially by both small scale and commercial farmers to support the export drive (Norman, 1992). There is a huge market demand in Ghana for sweet pepper for export; therefore its production needs to be expanded. For instance in 2009, the Millennium Development Authority (MDA) supported some farmer groups in the Kwahu East District of the Eastern Region to produce and sell 5.6 tonnes of sweet pepper at GH¢5,700 to the United Kingdom University of Ghana http://ugspace.ug.edu.gh 2 through Dhillon Farm Limited, a vegetable exporting company located in Accra (ModernGhana.com, 2009) 1.1 Problem Statement In Ghana and West Africa as a whole, sweet peppers are grown for both local consumption and export. Its production is limited almost entirely to the urban centres (Norman, 1992). In Ghana, sweet pepper is mainly rain-fed crop, and during the dry season there is some production along river valleys. Most small scale farmers who operate as out growers for export companies grow sweet pepper crops by operating on rain-fed basis. In the dry season, stunted growth, poor fruit set or dropping of flowers and young fruits may occur as a result of dry soils. To meet the high demand of sweet pepper for local consumption, some growers resort to irrigation to take care of irregular rains during the wet seasons, the late minor season and the long dry season occurring between November and March. Moisture supply for the best production of sweet pepper must be uniform during the growing season. It is therefore important for small scale farmers to adopt horticultural practices such as mulching to conserve soil moisture (Norman, 1992) in order to optimise productivity. Mulching is the application of a covering material to the soil surface (Norman, 2004). The use of polyethylene as a mulch with irrigation is a widespread practice in commercial vegetable production systems. However, polyethylene has some disadvantages such as; difficulty of removal, cost of disposal, increased soil erosion and increased agricultural chemical runoff (Lamont, 1993; Hochmuth, 1998; Brown and Channell- Butcher, 2001; Rice et al., 2001). Disposal of the mulch is increasingly becoming problem and costly to growers and society. Disposal cost in some areas has increased by as much as 30% in one year (Servis, 1992). Besides the problem associated with its disposal, the cost of polyethylene is also not within the reach of most small-scale producers. An alternative to the use of plastic mulch is the use University of Ghana http://ugspace.ug.edu.gh 3 of organic mulch. Organic mulch systems are recyclable in the soil, reduce production cost and benefit the environment. Surface mulching has been shown to reduce evaporation and decrease salinity hazards (Yang et al., 2006). Organic mulch keeps the surface layer wetter and helps to increase root growth (Gajri et al., 1994). It has also been found to reduce day time temperature and conserve moisture, increase growth and yield attributes of vegetables (Adetunji, 1990). Organic mulching has been used to obtain good growth and yield in pepper (Aiyelaagbe and Fawusi 1986; Rahman et al., 2006). Organic mulch improves physical, chemical and biological properties of soil, as it adds nutrients to the soil and ultimately enhances the growth and yield of crops (Dilipkumar et al., 1990). Organic mulches reduce soil erosion, and may have advantages of low cost, with no removal requirement (Isenberg and Odland, 1950; Aparbal-Singh et al., 1985; Roe et al., 1992; Singh, 1992). Organic mulches have also been shown to improve soil quality and stimulate soil microbial communities due to the addition of organic matter (Lalande et al., 1998; Ozores-Hampton, 1998; Oslen and Gounder, 2001). Organic mulches can reduce evaporation of water from the soil surface, suppress weed growth, and restrict leaching of fertilizer nutrients and moderate diurnal and seasonal temperature fluctuations (Janick et al., 1986). A good mulch must be economical, available, easy to handle and must be stable so that it will not easily wash or blow away (Norman, 2004). In Ghana some common materials used for mulching include sawdust, grass straw, grain straw, corncobs and plastic film. Even though these mulch materials are easy to handle and stable when applied, some of them are fed to livestock and used to set fire making them hard to come by and uneconomical. Although there is some research on the benefits and use of organic mulches as an alternative to polyethylene mulches, there is little or no research about the use of local materials such as empty palm fruit bunches, rice husks and cocoa pods as organic mulches on sweet pepper University of Ghana http://ugspace.ug.edu.gh 4 production in Ghana. There is the need, therefore, to investigate the effect of organic mulches (dry rice husks, dry empty palm fruit bunches and dry cocoa pod husks) as related to the production of green pepper under rain fed conditions in Ghana. The choice of these organic mulch materials is due to their availability, economical, easy to handle and transport and ability to decompose easily. 1.2 Objectives The study is aimed at ascertaining the effects of organic mulches (cocoa pod husks, empty palm fruit bunches and rice husks) on the growth and yield of sweet pepper. Specifically the experiment is aimed at: 1. Determining changes in soil temperature and moisture under organic mulches. 2. Assessing the ability of weed suppression by various organic mulches in sweet pepper field. 3. Assessing the growth and yield of sweet pepper under organic mulches. University of Ghana http://ugspace.ug.edu.gh 5 CHAPTER TWO LITERATURE REVIEW The literature pertaining to the use of organic mulches (dry cocoa pods, rice husks and empty palm fruit bunch) on growth and yield of sweet pepper is very scarce, so the combined effect of organic mulches on peppers as well as on few of the related crops has been reviewed and presented in this chapter. 2.1 Climatic requirements of sweet pepper Sweet pepper is a warm-season crop, which grows well under an extended frost-free season, with the capability of producing high yields of exceptional quality. It is easily destroyed by frost and at temperatures between 5 an 15°C, it performs poorly (Bosland and Votava, 1999). The best temperature range for sweet pepper growth is 20-25°C When sweet pepper seed is sown at too low soil temperatures, germination is slow but as temperatures increase to between 24-30°C seedling emergence accelerates (Bosland and Votava, 1999). The best soil temperature for germination is 29°C Low temperatures also reduce the growth of seedling leading to prolonged seedling exposure to insects, diseases, salt or soil crusting, any of which can badly damage or kill the seedlings (Bosland and Votava, 1999). The productivity of many plant species of which sweet pepper is of no exception is adversely affected by high temperatures. Sweet pepper needs optimum day/night temperatures of 25/21°C during flowering. The flowers are aborted and yield is reduced when they are exposed to temperatures as high as 33°C for longer than 120 hours. Pollen becomes non-viable and appears to be deformed, empty and clumped when exposed to high temperatures (>33°C) (Erickson and Markhart, 2002). Temperatures lower than 16°C can lead to fruitless plants (Coertze and Kistner, 1994). When daily air temperature ranges between 18-32°C during fruit set, higher yields are obtained (Bosland and Votava, 1999). Prolonged high relative humidity University of Ghana http://ugspace.ug.edu.gh 6 and temperatures above 35°C reduce fruit set. Normally fruits that are formed during high temperature conditions are deformed. Sweet peppers are also sensitive to sunscald (Coertze and Kistner, 1994). Temperatures above 21°C hasten the development of fruit colour (Bosland and Votava, 1999). 2.2. Soil requirements of sweet pepper Sweet peppers grow in a wide range of soils, but do well preferably in well-drained, sandy loam or loamy soil with a good water-holding capacity and rich in humus. Soils deeper than 400 mm are needed. Plants can be planted on ridges in shallow soils with a poor drainage capacity (Coertze and Kistner, 1994). Their effective depth of root is between 400-700 mm. Soils with a pH (H2O) range of between 5.5 and 6.8 is preferable for sweet pepper production. Sweet pepper is fairly sensitive to soil salinity. Soil with 50 percent or more electrical conductivity (EC) of 5 ds m -1 can reduce sweet pepper yield. Sweet pepper yield can also be reduced by certain nematode species which damage pepper roots (Bosland and Votava, 1999). 2.3 Use of mulches in vegetable production Man has come out with technologies since the beginning of civilization to maximize the efficiency of food production. One of these traditional techniques that have been used since 1950’ is the utilisation of mulch in commercial vegetable production. When mulch is placed over the soil surface, a favourable soil-water-plant relation is created. The microclimate surrounding the plant and soil is greatly influenced by mulch that is the thermodynamic environment, the moisture, the crop growth and yield. For commercial production of vegetable crops in many regions of the world, the use of mulch has become an important cultural practice to maximize water use efficiency by the plant and to improve the growth. University of Ghana http://ugspace.ug.edu.gh 7 Organic or inorganic soil mulches influence the crop in many ways. Barrier can be provided by plastic mulches against weeds, moisture loss, nutrient loss, erosion, insect and disease injury while enhancing plant establishment and an earlier crop of higher quality. Organic mulching improves physical, chemical and biological properties of soil, as it releases nutrients to the soil and ultimately facilitates the growth and yield of crops (Dilipkumar et al., 1990). Organic Mulching possesses an advantage for increased crop production through its positive effect on the soil environment which enhances crop growth and yield (Lal et al., 1980). Judicious use of crop residues help to maintain adequate infiltration rates, prevent surface crusting, improve aggregation of soil and modify the transport and retention of water, heat and air in the soil (Agyenim-Boateng and Dennis, 2001). It was also reported that physical, chemical and biological properties of soils are affected by crop residues. According to the authors, when crop residues are applied as surface mulch they influence the soil positively by conserving moisture, improving soil structure thereby enhancing aeration, infiltration and water-holding ability. The authors further stated that mulching also reduce high soil temperature, controls soil erosion by reducing runoff and heavy impact of rain drops and preventing leaching of nutrients, promoting the activities of soil microorganisms as well as reducing weed competition (Agyenim-Boateng and Dennis, 2001). Hochmuth et al (2001), reported that the main objectives of mulching are weed control, conservation of soil moisture and modification of temperature. Mulching effectively manipulates crop growing environment leading to increased yield and improved product quality by suppressing weed growth, ameliorating soil temperature, conserving soil moisture, reducing soil erosion, improving soil structure and enhancing organic matter content (Opara- Nadi, 1993; Hochmuth et al., 2001; Awodoyin and Ogunyemi, 2005). University of Ghana http://ugspace.ug.edu.gh 8 Nowadays mulching by either organic or inorganic materials are being utilised to protect plants from root borne diseases and for conservation of water. Organic mulches such as sawdust, dry grass, maize cobs, water hyacinth, rice and wheat straw have enhanced vegetative growth and yield through improving water content of soil, heat energy and addition of some organic nitrogen and other minerals to improve nutrient status of the soil (Yang et al., 2006). Vegetative growth as well as increased yield of vegetables are enhanced by mulching through improvement in the soil environment (Yang et al., 2006). 2.4 Types of mulches Lal (1987), defined mulching as the application of a layer of dissimilar material, separating the soil surface from the atmosphere. According to Wild (1988), mulches are organic or inorganic materials spread on the surface of the soil to protect it from the full force of the sun, raindrops and wind which may otherwise induce surface crusting, freezing and evaporation of the bare soil. Mulching is the application of covering layer of material to the soil surface (Norman, 1992). Stigter (1984), stated that materials used by traditional farmers include; leaves, dried or fresh banana leaves, grass, straw, maize stalk, crop residues, ash, animal dung and household rubbish. Traditional farmers use organic mulch materials such as cereal straw and stalk, crop debris, sawdust, leaves, grass, maize stover, weeds, manure, Spanish moss, and various water plants. In modern or commercial agriculture, inorganic mulches used include aluminium foil, asphalt, paper, glass wool, petroleum mulch and various polythene mulches such as black or transparent polythene sheets (Thurston, 1997). The main types of mulches are organic materials obtained from plant and animal residues and inorganic materials which are usually synthetic in nature. University of Ghana http://ugspace.ug.edu.gh 9 2.5 Effect of organic mulches on soil moisture. According to Rajput and Singh (1970), straw mulch conserved higher soil moisture compared with bare soil. There has been significant rise in the average available soil moisture stored in the soil by mulching with wheat residue in comparison to bare soil (Black, 1973). Koni (1983), reported of better soil moisture conservation with the application of sorghum stubbles, cotton stubbles and maize stubbles as mulch in pepper than the bare soil. Mulch protects the soil from direct rays of the sun which would cause evaporation of moisture from the soil surface and cause drying of the soil profile. This leads to improved and higher soil moisture. According to Dilipkumar et al. (1990), mulching reduces soil water evaporation. Thus, it enhances more retention of soil moisture. Moisture retention of soil has been shown to be improved by the application of organic mulches. Mintah (1998), reported of higher soil moisture content on Mucuna pruriens mulched plot in comparison with no mulch plot. Several studies conducted by (Fraedrich and Ham, 1982; Unger, 1995; Schonbeck and Evanylo, 1998; Agele et al., 2000) have shown that mulching with organic materials conserved soil moisture and consequently increased crop production. Moisture contents of soils under organic mulches - grass straw, rice straw, rice husk and sawdust were higher than those in the control (Nkansah et. al., 2003). Ghosh et al. (2006), studied the growth and yield response of groundnut under wheat straw mulch and bare soil and reported that there was higher moisture content in wheat straw mulch plot than bare soil under field condition. Organic mulches helped to maintain soil moisture content longer than bare soil. Mulching conserves water by reducing evaporation and mitigates negative effects of water stress on plant growth and yield under semi-arid conditions. Mulching conserves moisture contents which in turn results in increase in the plant growth. (Nasir et al., 2011). University of Ghana http://ugspace.ug.edu.gh 10 2.5.1 Effect of organic mulches on soil temperature Mulching aids in the control of temperature fluctuations (Dilipkumar et al., 1990). Mintah (1998), observed that Mucuna pruriens mulched plots had lower soil temperature compared to that of no mulch plots. Agele et al. (2000), studied the effect of tillage and mulching on the performance of post-rainy season tomato in the humid, south of Nigeria. He reported that mulching resulted in reduced soil temperature that led to increased yield. Several studies conducted by (Ashworth and Harrison, 1983; and Agele et al., 2000) have also shown that mulching with organic materials regulates soil temperatures and consequently increase crop production. Organic mulches - grass straw, rice straw, rice husk and sawdust were more effective in reducing soil temperature compared to the control (Nkansah et al., 2003). Gandhi and Bains (2006), reported that mulches moderate hydrothermal regime of the soil and modify the microclimate by modifying soil temperature. (Norman et al., 2011) found that dry Panicum maximum grass and sawdust mulches reduced soil temperature. 2.5.2 Effect of organic mulches on weed control. According to Dilipkumar et al. (1990), organic mulching reduces weed infestation and enhances growth and yield of crops. Increase in yield as a result of reduced crop-weed competition due to weed suppression by organic mulching has been reported by several workers (Roe et al., 1993; Unger, 1995; Hendrickson, 1997; Schonbeck and Evanylo, 1998). Mintah (1998), also reported that Mucuna pruriens mulched plots recorded the lowest weed population than the no mulch plots. According to Nkansah et al. (2003), grass straw, rice straw, rice husk and saw dust mulches significantly reduced fresh weed weight. They also stated that grass straw mulch significantly reduced fresh weed weight while the highest fresh weed weight was observed in the control. According to Norman et al (2011), dry grass and sawdust mulches suppressed weed growth significantly. University of Ghana http://ugspace.ug.edu.gh 11 2.5.3: Effect of organic mulches on plant growth. 2.5.3.1 Leaf area Mintah (1998), reported that no mulch plots recorded the lowest leaf area compared to Mucuna pruriens mulched plots. Norman et al. (2002), studied the effect of grass mulch on the growth and yield of sweet corn in Ghana and reported that grass mulch increased leaf area of sweet corn. Acording to Ojeniyi et al. (2007), Cocoa husk increased leaf area of tomato compared to the control. Venkanna (2008), observed increase in chilli leaf area and leaf area index under glyricidia mulch and crop residue mulch over no mulch treatment. In an experiment to determine the growth and yield response of okra to different organic manures, it was observed that leaf area was significantly influenced compared to the control (Abd El-Kader et al., 2010). According to Iftikhar et al. (2011), organic mulch materials maintain soil moisture and raise soil temperature and consequently resulted in increased leaf area. 2.5.3.2 Number of leaves per plant Lantana leaves and grass mulches maintained higher number of leaves as compared to unmulched treatments of capsicum (Thakur et al., 2000). Leaf number of sweet corn increased by the application of dry grass mulch (Norman et al., 2002). Mulching increased the number of lettuce leaves per plant than no mulch (Moniruzzaman, 2006). Tomato plants grown in pots mulched with wild sunflower leaves recorded the highest number of leaves per plant over those grown in unmulched pots (Liasu and Abdul, 2007). In an experiment to determine the growth and yield response of okra to different organic manures, it was observed that number of leaves per plant was significantly higher under mulched treatments compared to the control (Abd El-Kader et al., 2010). The greater number of leaves per chilli plant was recorded in rice straw mulch followed by wheat straw mulch and sugarcane bagasse mulch. Control plants recorded the lowest number University of Ghana http://ugspace.ug.edu.gh 12 of leaves per plant, (Iftikhar et al., 2011). Dauda (2011), also reported that grass mulch recorded the highest number of pepper leaves at 10 weeks after plating compared to the control. Iftikhar et al. (2011), also observed that in a pot experiment, chilli plants grown in rice straw mulch produced the maximum number of leaves followed by wheat straw mulch and sugarcane bagasse mulch. The minimum number of leaves was recorded by the control (no mulch). Dry grass mulch plants recorded the highest okro leaf number compared to the control plants (Norman et al., 2011). 2.5.3.3 Number of branches In his experiment to study the effect of Lantana leaves and grass mulches on growth and yield of capsicum, Thakur et al. (2000), reported that Lantana leaves and grass mulches maintained higher number of branches as compared to unmulched treatments. Gandhi and Bains (2006), reported of higher number of tomato plants branches under straw mulch as compared to no mulch. Number of branches of chilli recorded at different stages of crop growth was significantly higher with application of glyricidia mulch and crop residue mulch over no mulch. Cocoa husk increased number of branches of tomato plant compared to the control (Ojeniyi et al., 2007). (Venkanna, 2008). In an experiment to determine the growth and yield response of okra to different organic manures, branch number was influenced significantly by mulching (Abd El- Kader et al., 2010). Dauda (2011), reported of no significant effect on the number of branches per pepper plant by Grass mulch compared to the control. Dry grass mulch produced higher number of branches in okro than control (Norman et al., 2011). 2.5.3.4 Plant height Thakur et al. (2000), reported of higher plant height of capsicum under Lantana leaves and grass mulches compared to unmulched treatments. Norman et al. (2002), reported that grass University of Ghana http://ugspace.ug.edu.gh 13 mulch increased sweet corn height. According to Nkansah et al. (2003), organic mulches increased tomato plant height than the control. Lettuce plant height was significantly increased by mulching more than control (no mulch), (Moniruzzaman, 2006). According to Awodoyin et al. (2007), the highest plant height of tomato was recorded under wood chips and grass mulches over the control (unmulched). Liasu and Abdul (2007), observed higher plant height of tomato plants in pots mulched with wild sunflower leaves compared to those in unmulched pots. Acording to Ojeniyi et al. (2007), cocoa husk increased tomato plant height compared to the control. Significantly higher plant height was recorded in chilli with the application of Glyricidia loppings used as mulch over no mulch control plots. But, it was at par with application of Crop residue mulch (grasses/plant materials/weeds) (Venkanna, 2008). In an experiment to determine the growth and yield response of okra to different organic manures, it was observed that there was significant influence of chicken manure and plant residues on plant height compared to control (Abd El-Kader et al., 2010). According to Iftikhar et al. (2011), mulch material had significant effect on plant height. The highest chilli plant height was noted in rice straw mulch followed by sugarcane bagasse mulch and wheat straw mulch. The lowest plant height was recorded in control plants. Pepper plant height was significantly higher on grass mulch plots compared to the control (Dauda, 2011). High vegetative growth was observed in grass and sawdust mulches. Okro plants on grass mulched plots recorded significant height than the control plants at fruit set (Norman et al., 2011). Sawdust mulch increased hot pepper plant height more than the control (Norman et al., 2011). 2.5.3.5 Canopy width Capsicum plants grown on plots mulched with Lantana leaves and grass mulches maintained higher canopy width compared to plants on unmulched plots (Thakur et al., 2000). Mulching University of Ghana http://ugspace.ug.edu.gh 14 have also been found to increase canopy width of lettuce plant compared with unmulched plants (Moniruzzaman, 2006). Increased hot pepper canopy size was observed on sawdust mulch compared to the control (no mulch) (Norman et al., 2011). 2.5.3.6 Stem diameter Lantana leaves and grass mulches maintained higher stem diameter as compared to unmulched treatments of capsicum (Thakur et al., 2000). Grass mulched plots produced higher stem diameter of sweet corn than control plots (Norman et al., 2002). Grass mulch recorded the highest stem girth of tomato plant compared to control (unmulch) plot (Awodoyin et al., 2007). Okro stem diameter was increased by applying plant residues and chicken manure compared to the control (Abd El-Kader et al., 2010). 2.5.3.7 Plant dry matter Norman et al. (2002), stated that grass mulch increased sweet corn leaf dry matter more than control. Mulching produced maximum dry weight of lettuce plant than no mulch (Moniruzzaman, 2006). Application of glyricidia mulch recorded higher dry matter production as compared to no mulch and further crop residue mulch (Venkanna, 2008). Norman et al. (2011), also reported of maximum dry upper plant biomass of okro plants by dry grass mulch compared to the control plants. 2.5.4 Effect of organic mulches on flowering and harvesting 2.5.4.1 Number of days to flower According to Ravindrkumar and Shrivastav (1998), organic mulches enhanced early flowering in tomato crop over control. Norman et al. (2002), reported of early teaselling of sweet corn under grass mulch compared to bare soil. Mulch material reduced number of days to flower. It took minimum days for chilli plants to flower in wheat straw mulch followed by University of Ghana http://ugspace.ug.edu.gh 15 plants in rice straw mulch and plants in sugarcane bagasse mulch. Control plants took maximum days to flower (Iftikhar et al., 2011). 2.5.4.2 Number of days to fruit set Vos and Sumarni (1997), observed quick plant growth and early fruiting in hot pepper with straw mulching compared to control. Organic mulches enhanced early fruit set in tomato over the control (Ravindrkumar and Shrivastav, 1998). Sweet corn plants under grass mulch reached early silking than those on control plots (Norman et al., 2002). 2.5.4.3 Number of days to first fruit harvest According to Ravindrkumar and Shrivastav (1998), organic mulches reduced number of days to harvest in tomato crop. Sweet corn plants under grass mulch also reached harvesting earlier than those on control plots (Norman et al., 2002). In their studies on the effect of mulching on growth and yield of chilli, Iftikhar (2011) observed that the mulch materials (rice straw, wheat straw and sugarcane bagasse) reduced the number of days to first harvest of chilli. It took the minimum number of days to first harvesting in rice straw mulch followed by wheat straw mulch plants and sugarcane bagasse respectively. Control plants recorded the maximum numbers of days for first harvest (Iftikhar et al., 2011). 2.5.5: Effect of organic mulches on plant yield 2.5.5.1 Mean fruit weight Vos and Sumarni (1997), observed increased fruit weight of hot pepper with straw mulching compared to control. According to Gandhi and Bains (2006), tomato plants under straw mulch recorded higher fruit weight as compared to no mulch. Fruit weight of chilli was significantly higher with the application of glyricidia mulch followed by crop residue mulch at the same quantity as compared to no mulch (Venkanna, 2008). (Iftikhar et al. (2011), observed that Sugarcane bagasse, rice straw, and wheat straw mulches significantly University of Ghana http://ugspace.ug.edu.gh 16 influenced chilli fruit weight. Sugarcane bagasse mulch recorded the highest fruit weight followed by rice straw, wheat straw and control in that order. Plant residues and chicken manure significantly influenced okro fresh fruit weight compared to the control (Abd El- Kader et al., 2010). Dry grass mulch recorded higher mean fruit weight of okro than the control (Norman et al., 2011). Sawdust mulch recorded the maximum mean fruit weight of pepper than the control (Norman et al., 2011). 2.5.5.2 Fruits weight per plant Both grass mulched plots and bare soil in summer and winter produced no significant difference on growth and yield parameters of bell pepper, but bell pepper grown on grass mulch plots produced higher total number of weight of fruits than those on bare soil (Manuel et al., 2000). According to Norman et al. (2002), there were increased fresh ear weights of sweet corn from plants under grass mulch compared to those from control plants. Cocoa husk increased tomato fruits weight per plant compared to the control (Ojeniyi et al., 2007). The total fresh weight of sweet pepper fruit per plant during an experiment revealed that grassed mulched recorded the highest value compared to the control (unmulched) which had the lowest value (Dauda, 2011). Dry grass mulch produced higher fruits weight of okro per plant than the control (Norman et al., 2011). Sawdust mulch recorded the maximum weight of pepper fruits per plant than the control (Norman et al., 2011). 2.5.5.3 Number of fruit per plant Chakraborthy and Sadhu (1994), observed increased number of tomato fruit with water hyacinth mulch more than rice straw mulch. Bell pepper grown on grass mulch plots produced higher total number of fruits than those on bare soil both in summer and winter (Manuel et al., 2000). Norman et al. (2002), reported of higher number of sweet corn ear by the application of grass mulch compared to control. Organic mulches had the highest tomato University of Ghana http://ugspace.ug.edu.gh 17 fruit number per plant than the control. Rice husk mulch recorded the highest fruit number per plant over rice straw, grass straw and sawdust mulches (Nkansah et al., 2003). Grass mulch recorded the highest number of fruits per tomato plant followed by wood chip mulch in comparison to control (Awodoyin et al., 2007). The number of fruits produced during the first week of fruit production was highest in tomato plants in pots mulched with wild sunflower leaves while plants in unmulched pots had the lowest number of fuits per plant (Liasu and Abdul, 2007). Acording to Ojeniyi et al (2007), Cocoa husk increased number of tomato fruits compared to the control. The number of chilli fruits per plant differed significantly with glyricidia mulch and with crop residue mulch compared to no mulch (Venkanna, 2008). The use of mulch material influenced the number of chilli fruits per plant. The highest fruit number per plant was recorded in sugarcane bagasse mulch followed by rice straw mulch and wheat straw mulch. Control recorded the lowest fruit number per plant (Iftikhar et al., 2011). The highest mean number of sweet pepper fruits per plant was observed on grass mulch plots over the control. (Dauda, 2011). Higher number of okro fruits per plant was recorded in plants on grass mulch than those on the control (Norman et al., 2011). 2.5.5.4 Yield per hectare Okra production increased significantly under straw mulch followed by saw dust mulch over control (Batra et al., 1985). The application of straw mulch increased tomato and okra yield over control (Gupta and Gupta., 1987). According to Dilipkumar et al. (1990), under rain fed situations mulching increased the yield over no mulching. Tomato yields were higher in organic mulched plots than the control. Gollifer (1993), reported that application of organic mulch resulted in increased chilli dry fruits yield compared to control. Organic mulch had the highest fruit yield of bell pepper over control (Rose et al., 1994, Hassan et al., 1994). Significant higher yield of tomato was reported under hairy vetch mulch than bare soil (Aref University of Ghana http://ugspace.ug.edu.gh 18 et al., 1996). Vos and Sumarni (1997), observed increased yield of hot pepper with straw mulching compared to control. Lantana leaves and grass mulches maintained higher growth and yield parameters in capsicum as compared to unmulched treatments, yield levels increased in lantana leaves and grass mulched plants over unmulched plants (Thakur et al., 2000). Norman et al. (2002), reported that grass mulch increased total ear yield of sweet corn more than control. Rice husk mulch had significantly higher yield than the control (Nkansah et al., 2003). Gandhi and Bains (2006), found out that tomato plant under straw mulch recorded higher fruit yield as compared to no mulch. Significantly higher fresh yield of lettuce was recorded from mulch treated plot than that from control (Moniruzzaman, 2006). According to Awodoyin et al. (2007), wood-chips mulch recorded the highest fruit yield of tomato followed by grass mulch compared to the control (unmulched) plots. The application of glyricidia loppings as mulch recorded significantly higher dry fruit yield of chilli as compared to no mulch treatment. (Venkanna, 2008). Cover crops and the application of organic mulches increased tomato yield more than control (Qingren et al., 2008). Plant residues and chicken manure recorded the highest green fruit yield of okra compared to the control (Abd El-Kader et al., 2010). Grasse mulch plots recorded the highest yield of sweet pepper per hectare over the control (unmulched) ( Dauda, 2011). The average cucumber and Bitter gourd production under mulch condition was significantly higher compared to values obtained in control treatments. (Nasir et al., 2011). Higher total okro fruit yield was observed in plants on grass mulch than those on the control (Norman et al., 2011). The highest total fruit yield of hot pepper was produced by sawdust mulch than the control (Norman et al., 2011). Bare soil plots resulted in lowest yield of University of Ghana http://ugspace.ug.edu.gh 19 tomato but this was not significantly different from yields obtained from mulched plots (Osei-Bonsu and Asibuo, 2013). 2.5.6 Effect of organic mulches on fruit quality 2.5.6.1 Fruit length Sugarcane bagasse mulch recorded the maximum chilli fruit length. This was followed by wheat straw mulch and rice straw mulch. No mulch material recorded the lowest fruit length (Iftikhar et al., 2011). Grass mulch recorded the same length of pepper fruit compared to the control (Dauda, 2011). Dry grass mulch recorded higher mean fruit length of okro than the control (Norman et al., 2011). Sawdust mulch produced the highest mean fruit length of hot pepper compared to the control (Norman et al., 2011). 2.5.6.2 Fruit width The application of mulch material influenced chilli fruit width. Iftikhar et al., (2011) found that sugarcane bagasse mulch recorded the highest fruit width followed by rice straw mulch and wheat straw mulch while control produced the lowest fruit width. Mulching materials had significant influence on fruit width of pepper. The highest mean fruits diameter was recorded on the grassed mulched plots over the control (unmulched) (Dauda, 2011). Mean fruit diameter of okro was not significantly affected by dry grass mulch, sawdust mulch and the control (no mulch), (Norman et al., 2011). Maximum mean fruit diameter of hot pepper was recorded by sawdust mulch compared to the control (Norman et al., 2011). 2.5.7 Effect of organic mulches on net return According to Sutagundi (2000), treatment receiving straw mulch resulted in significantly higher net return compared to the control. University of Ghana http://ugspace.ug.edu.gh 20 CHAPTER THREE MATERIALS AND METHODS The present investigation was carried out at the University of Ghana Forest and Horticultural Crops Research Centre (FOHCREC), Kade from July, 2012 to March, 2013 with the objective of understanding the effect of organic mulches on growth and yield attributes of sweet pepper. The details of materials used and methods adopted during the course of investigation are outlined in this chapter. 3.1 Experimental site The centre is at Okumaning near Kade (latitude 6º 09 and 6º 06 N and longitude 0º 55 and 0º 49 W and 135.9 m above sea level). It is located in the semi-deciduous forest agro-ecological zone of Ghana in the Kwaebibrim District of the Estern Region. The soils of the experimental site are well drained. They are classified as the forest Ochrosol Great Soil by the Ghanaian soil classification system (Brammer, 1962; Owusu-Benoah et al., 2000) and are generally classified as Acrisols (Offin series) in the FAO-UNESCO Revised Legend (FAO, 1998). The study site is characterized by a bi-modal rainfall pattern with peaks in June and October and a short dry spell in August while the major dry season stretches from December to February. The climatic conditions during the experimental period are presented in Table 3.1. University of Ghana http://ugspace.ug.edu.gh 21 Table 3.1: Climatic data during the experimental period Month Total monthly rainfall (mm) Temperature (˚C) Mean Mean monthly monthly (maximum) (minimum) July 2012 150.9 29.3 21.7 August 2012 21.6 28.8 21.3 September 2012 131.5 31.1 22.0 October 2012 218.8 31.6 21.9 November 2012 110.3 32.5 21.1 December 2012 32.8 32.2 21.6 January 2013 0.1 33.7 20.4 February 2013 45.2 35.2 22.4 March 2013 228.5 34.1 22.3 Source: University of Ghana Forest and Horticultural Crops Research Centre (FOHCREC), Kade. 3.2 Soil characteristics of the experimental site Soil samples were collected from the field before layout of the experiment for the determination of the soil properties. The soil samples collected from 0 to 30cm depth were dried under shade and were pounded with wooden pestle in a mortar to pass through 2 mm University of Ghana http://ugspace.ug.edu.gh 22 sieve. The composite soil was used for analysis. The initial soil chemical and physical properties from the experimental site are presented in Table 3.2 Table 3.2 Initial soil chemical and physical properties from the experimental site 3.3 Experimental details The experiment was conducted for two seasons, the first one commenced in July, 2012 and ended in December, 2012 while the second one started in December, 2012 and ended in March, 2013. Both experiments were conducted in a randomised complete block design with four replicates. The treatments evaluated included dry cocoa pod husks, empty palm fruit bunches, rice husks, all as mulches at the rate of 35t/ ha each and a control (bare soil). Each plot measured 3.6m x 8.1m. Each treatment consisted of five rows of ten plants each per plot (50 plants / plot). The sweet pepper cultivar planted in this experiment was Yolo Wonder. 3.4 Cultural practices 3.4.1 Land preparation The site which was previously cropped to maize was prepared for planting by clearing with cutlasses in June, 2012. Four weeks later, the field was sprayed with (Sunphosate (Glyphosate) herbicide at a rate of 900 g a.i per hectare). At two weeks after spraying, stumps and debris were removed from the experimental area. These were followed by lining and pegging of the area into blocks and plots. Both blocks and plots were separated by 1 m buffer. Ph OC % N % P mg/k g K cmol /kg Na cmol /kg Ca cmol /kg Mg cmol /kg CEC cmol /kg % Sand % Silt % Clay 5.1 2.79 0.21 7.84 0.15 0.13 4.0 3.6 18.2 48.88 26.12 25.0 University of Ghana http://ugspace.ug.edu.gh 23 3.4.2 Raising of nursery The nursery area was cleared with cutlass and sprayed with pesticide (Cidym super) at the rate of 35 mls per 15 l of water. A nursery box of 2.5m length, 1.5m width and 20cm height was filled with carbonated rice husk. A shed was erected over the nursery box. 3.4.3 Sowing of seeds and after care Seeds of sweet pepper, variety- Yolo Wonder purchased from Agrimat, Madina – Accra were sown on 9 July 2012 for the first planting and on 5 November 2012 for the second planting in drills of 10cm apart in seed box and watered. Rain was alternated with watering in the evening hours up to the time of transplanting. Seedlings were fertigated with 20g of NPK dissolved in 2 litres of water weekly. As a preventive measure against pests- grasshoppers and crickets, seedlings were sprayed with Cidym Super fortnightly. 3.4.4 Transplanting Sweet pepper seedlings of 6 weeks old were transplanted out on the field on 20 August 2012 for the first planting and on 11 December 2012 for the second planting at a spacing of 90cm x 90cm. One week later, the mulch materials were applied as indicated above. 3.4.5 Application of manures and fertilizers The plants were side-dressed with N.P.K. (15:15:15) fertilizer at the rate of 300kg /ha in two splits; one-half at two weeks after transplanting and another one-half two weeks later. The plants were side-dressed again with sulphate of ammonia at the rate of 250kg /ha at flowering, that is about 5 weeks after planting. 3.4.6 Irrigation The plants were irrigated uniformly at an interval of 3 days depending upon the soil and climate conditions so as to maintain adequate moisture in root zone in open field conditions. The irrigation was done using watering cans. University of Ghana http://ugspace.ug.edu.gh 24 3.4.7 Crop protection measures Weeds were controlled by hand picking at 3 weeks interval. Grasshoppers, crickets, termites, beetles and ants were controlled as and when necessary using Cydim Super at the rate of 35 ml per 15 l of water fortnightly to reduce pest damage. 3.5 Data collection The data was collected on the following parameters; plant height, number of leaves per plant, leaf area, number of branches per plant, stem diameter, canopy size, dry weight of upper plant biomass, days to first flowering, days to 50% flowering, days to first fruit harvest and days to 50% fruit harvest. Others were number and weight of fruits per plant, mean fruit weight, fruit length, fruit width, marketable and non marketable fruits, days to final fruit harvest, cropping period, soil temperature, soil moisture content, weed biomass, assessment of insects and capsicum chlorosis disease. Leaf area index was calculated and economic analysis was done. 3.5.1 Growth parameters Five randomly selected plants were tagged in each treatment plot for recording growth parameters and the mean of the observations on these 5 plants was computed and recorded. 3.5.1.1 Plant height The height of the plants was measured in centimetres from the ground level to the tip of the main shoot at 50% flowering. A ruler was used to measure the height. University of Ghana http://ugspace.ug.edu.gh 25 3.5.1.2 Stem diameter The diameter of the main stem of the plant was measured in millimetres at 2 cm above the ground level with the help of vernier caliper at 50% flowering. 3.5.1.3 Number of branches per plant At 50% flowering, the number of branches on each tagged plant was counted and mean number of branches per plant was recorded. 3.5.1.4 Number of leaves per plant The number of leaves born by each tagged plant was counted at 50% flowering. Mean number of leaves per plant was calculated and recorded. 3.5.1.5 Leaf area per plant Leaf area was measured at 4 WAT by disc method and was expressed in (cm 2 ). 20 leaf discs of known size were taken through a cork borer from randomly selected leaves of five plants, which were uprooted to record by dry matter accumulation from each experimental plot. Weight (g) and area of the discs (cm 2 ) were determined and leaf area per plant was computed. 3.5.1.6 Leaf area index (LAI) LAI was worked out by dividing the leaf area by land area. Land area was determined from the planting distance, that is 90cm × 90cm. 3.5.1.7 Dry matter production and its accumulation in different plant parts Electric oven dry weight (drying at 70ºC for 72 hrs. to a constant weight) of different parts were recorded by partitioning of whole plant into stem and leaves at 4 WAT. The sum of University of Ghana http://ugspace.ug.edu.gh 26 mean dry weight of all the plant parts represented the total dry matter per plant (g). Dry matter per hectare was also computed and expressed in Kg/ha. 3.5.1.8 Plant canopy The plant canopy was measured from North to South and East to West directions at 50 percent flowering by the use of a centimetre rule. The values were added up and average was striked to represent plant spread. 3.5.1.9 Days to 50 per cent flowering The number of days taken from the date of planting to flower opening of 50 per cent of the tagged plants (plants on the plot except the border plants) were counted and recorded. 3.5.1.10 Days to first fruit set Numbers of days taken from the date of planting to the appearance of first fruit were counted and recorded as days taken to fruit set. 3.5.1.11 Days to 50 per cent fruit set The number of days taken from the date of planting to the fruit set of 50 percent of the tagged plants (plants on the plot except the border plants) were counted and recorded. 3.5.1.12 Days to final fruit harvest The number of days taken from the date of first fruit harvest to the harvest of last fruit. The data was taken on the record plants. 3.5.2 Yield parameters The five tagged plants used for recording growth parameters were also used for recording the yield parameters. The following data were recorded. University of Ghana http://ugspace.ug.edu.gh 27 3.5.2.1 Number of fruits per plant The total number of fruits harvested from five tagged plants were counted from all the pickings and average was computed and recorded as number of fruits per plant. 3.5.2.2 Fruits weight per plant The fresh fruit weights of fruits harvested from five tagged plants for 7 times from each experimental plot were summed up and average was computed and recorded as fruits weight per plant. The weight was taken by using electronic balance. 3.5.2.3 Weight of fruits per hectare The weight of fruits per plot was used to compute the weight of fruits per hectare and expressed in Kg/ha. 3.5.2.4 Fruit length The lengths of fruits harvested from five tagged plants for seven times from each experimental plot were summed up and average was computed and recorded in centimetres as fruit length per plant. The length was recorded from the pedicel end of the fruits to the proximal end of the fruit using a cm rule. 3.5.2.5 Fruit width Recorded breadths of fruits used for recording the length were totalled and average was calculated and recorded in centimetres as fruit width. Vernier calliper was used to measure the breadth at the point of maximum breadth. 3.5.2.6 Marketable and unmarketable fruits Sweet pepper fruits harvested from five tagged plants for 7 times were sorted into marketable and unmarketable, counted and weighed. Fruits damaged by insect and or disease were University of Ghana http://ugspace.ug.edu.gh 28 grouped as unmarketable. Mean number and weight of marketable and unmarketable fruits were calculated from the total number and weight of marketable and unmarketable fruits. 3.5.3 Soil parameters 3.5.3.1 Soil moisture content Soil moisture content at a depth of 0-20cm was assessed five times at weekly interval (4, 5, 6, 7 and 8 WAP during the afternoons at 1:00 pm. 100g of fresh soil sample per each experimental plot was taken and air dried for 4 weeks. The dry weight was taken and percentage soil moisture content was computed and expressed in percent. 3.5.3.2 Soil temperature A soil thermometer was used to assess soil temperature at a depth of between 5 to 10 cm five times at weekly interval (4, 5, 6, 7 and 8 WAP) during the afternoon at 1:00 pm. Three readings were taken randomly per experimental plot and the mean calculated and expressed in degree Celsius. 3.5.4 Weed parameter 3.5.4.1 Weed biomass The prevalent weeds on the site included Cyperus rotundus, Euphorbia heterophylla, Chromolaena odorata,Commelina benghalensis and Calopogonium mucunoides. Weight of fresh weeds taken from randomly thrown quadrat of 50cm 2 (three times) on each experimental plot before weed control at 4 WAP was recorded in grams. Average weight of weed biomass was calculated and divided by the area of the quadrat and expressed in gram per square centimetre (g/cm 2 ). The weed biomass was weighed using an electric weighing scale. University of Ghana http://ugspace.ug.edu.gh 29 3.5. 5 Disease assessment 3.5.5.1 Assessment of severity of Capsicum chlorosis disease (CaCD) During the course of work, observation of foliar symptoms and the presence of thrips on some plots were made. Record plants were assessed for the severity of suspected Capsicum Chlorosis Disease (CaCD) which is caused by Capsicum Chlorosis Virus (CaCV) believed to have been transmitted by the thrips. Symptoms observed include; Yellowing (chlorosis) of leaf margins and areas between veins on younger leaves, curling of leaves, plants stunted, fruit distorted with dark spots and scarring. Disease severity was assessed using an arbitrary scale of 0 – 4 (Table 3.3). Each record plant was assessed for the severity of CaCD starting from 5 weeks after transplanting and repeated for 3 consecutive times at 2 weeks interval. Mean disease severity was calculated for each treatment. Whenever present, fruits were observed for the presence of symptoms stated above. Table 3.3: severity rating for CaCD Scale Description 0 No symptom 1 Mild deformation and curling of leaves 2 Moderate deformation and curling of leaves 3 Severe deformation and curling of leaves 4 Very severe deformation and curling of leaves 3.5.6 Economic analysis Financial analysis was carried out to evaluate the profitability of green pepper under the various mulch types. Involved in the analysis are; total revenue (TR) and cost of production (TC) per hectare from which net revenue was determined. The net revenue (NR) from the University of Ghana http://ugspace.ug.edu.gh 30 investment was given by NR = TR – TC. Return on investment (ROI) was also calculated as ROI = NR/TC × 100. 3.6 Data analysis Data on growth and reproductive parameters, soil temperature and moisture content and weed biomass were analysed using Analysis of Variance (ANOVA) for randomised complete block design. Least significance difference (LSD) at P = 0.05 was used to compare the means. However, excel was used to analyse data on disease assessment. University of Ghana http://ugspace.ug.edu.gh 31 CHAPTER FOUR RESULTS The findings and results of the effect of organic mulches (rice husk, empty palm fruit bunch and cocoa pod husk) on soil temperature, soil moisture, weed biomass, growth and yield of sweet pepper are presented in this chapter. 4.1 Effect of organic mulch on vegetative growth of sweet pepper at 50% flowering. The effect of organic mulch on vegetative growth parameters of sweet pepper in the rainy season is shown in Table 4.1. The mean plant height, leaf and branch number, canopy size and stem diameter were not significantly influenced by mulching. Also there were no significant differences in leaf area and leaf area index among the treatments. In the dry season, plants on mulched plots grew significantly taller than the plants on the control plots at 50% flowering (Table 4.2). Plants from the mulch treatments recorded significantly higher canopy size than plants from the control although there were no significant differences in canopy size among the different mulch materials. Significant differences were also observed in stem diameter between the mulch treatments and the control. Leaf and branch number were not significantly influenced by any of the four treatments. University of Ghana http://ugspace.ug.edu.gh 32 Table 4.1: Effect of organic mulch on vegetative growth parameters of sweet pepper at 50% flowering in the rainy season Mulch Number of Plant Leaf Number of Canopy Stem leaf leaf area type days to height number branches size diameter area index 50% flowering (cm) (cm) (mm) (cm2) Rice husk 39.0 18.75 55.0 7.0 23.90 8.2 256.0 0.0317 Palm fruit bunches 39.0 18.75 47.0 6.0 22.07 8.50 285.0 0.0352 Cocoa pod husk 37.0 17.25 42.0 6.0 23.60 8.00 279.0 0.0345 Control 37.0 19.75 48.0 7.0 28.79 8.25 251.0 0.0310 LSD (5%) 0.857 NS NS NS NS NS NS NS Table 4.2: Effect of organic mulch on vegetative growth parameters of sweet pepper at 50% flowering in the dry season Mulch Number of Plant Leaf Number of Canopy Stem type days to height number branches size diameter 50% flowering (cm) (cm) (mm) Rice husk 36.0 25.25 68.0 11.0 37.08 7.47 Palm fruit bunches 37.0 24.75 63.0 11.0 35.10 7.47 Cocoa pod husk 36.0 24.25 72.0 11.0 35.98 7.40 Control 36.0 20.00 45.0 8.0 25.90 5.40 LSD (5%) NS 3.90 NS NS 4.59 1.53 4.2 Mean and total dry shoot biomass There were no significant differences in above-ground mean and total dry plant biomass among the different treatments in the rainy season (Table 4.3). Empty palm fruit bunch mulch however recorded the highest mean dry shoot biomass compared to other mulch types. The University of Ghana http://ugspace.ug.edu.gh 33 highest total dry shoot biomass was produced by cocoa pod husk mulch while rice husk mulch recorded the lowest. Also, there was no significant difference in above-ground mean and total dry plant biomass between the different treatments in the dry season (Table 4.4), but rice husk mulch produced the highest mean and total dry shoot biomass among other mulch types while control recorded the lowest. Table 4.3: Effect of organic mulch on vegetative growth (mean and total dry shoot biomass) of sweet pepper at 3 WAT in the rainy season Mulch Mean dry shoot Total shoot Type biomass/plant (g) biomass (Kg/ha) Rice husk 0.27 3.37 Palm fruit bunches 0.35 4.37 Cocoa pod husk 0.33 4.10 Control 0.25 3.12 LSD (5%) NS NS Table 4.4: Effect of organic mulch on vegetative growth (mean and total dry shoot biomass) of sweet pepper at harvest in the dry season Mulch Mean dry shoot Total dry shoot Type biomass/plant (g) biomass (Kg/ha) Rice husk 17.7 219.0 Palm fruit bunches 11.1 137.0 Cocoa pod husk 13.5 167.0 Control 6.9 85.0 LSD (5%) NS NS University of Ghana http://ugspace.ug.edu.gh 34 4.3 Phenology Table 4.5 indicates the effect of organic mulch on the number of days to 50% flowering of sweet pepper in the rainy and dry seasons. The type of mulch material significantly affected the number of days to flowering in the rainy season. Plants from the rice husk mulch and palm fruit bunch mulch plots significantly took the longest time to reach 50% flowering while plants from the control and the cocoa pod husk plots took the shortest time to reach 50% flowering. In the dry season, days to 50% flowering was not significantly influenced by any of the four treatments however, plants from rice husk and cocoa pod mulches and the control took the shortest time to reach 50% flowering while plants from the empty palm fruit bunch mulch took the longest time to reach 50% flowering. Table 4.5: Effect of organic mulch on the number of days to 50% flowering of sweet pepper in the rainy and dry seasons Mulch Number of days to Number of days to Type 50% flowering in the 50% flowering in the rainy season dry season Rice husk 39.0 36.0 Palm fruit bunches 39.0 37.0 Cocoa pod husk 37.0 36.0 Control 37.0 36.0 LSD (5%) 0.857 NS University of Ghana http://ugspace.ug.edu.gh 35 4.4 Fruit set Table 4.6 shows data on the number of days to first and 50% fruit set of sweet pepper in the dry season. There were no significant differences in the number of days to first and 50% fruit set among the treatments. Table 4.6: Effect of organic mulch on number of days to first and 50% fruit set of sweet pepper in the dry season Mulch Number of Number of days type days to 50 % to first fruit set fruit set Rice husk 37 48 Palm fruit bunches 37 51 Cocoa pod husk 37 53 Control 36 49 LSD (5%) NS NS 4.5 Days to final fruit harvest and cropping period There was no significant difference in the number of days to final fruit harvest among the treatments in the dry season (Table 4.7). Period of harvest of sweet pepper was also not significantly influenced by any of the treatments (Table 4.7). University of Ghana http://ugspace.ug.edu.gh 36 Table 4.7: Effect of organic mulch on the number of days to final fruit harvest and period of harvest of sweet pepper in the dry season Mulch days to final period of type fruit harvest harvest Rice husk 86.0 38.0 Palm fruit bunches 89.0 37.0 Cocoa pod husk 87.0 35.5 Control 93.0 40.0 LSD (5%) NS NS 4.6 Yield and yield components. Table 4.8, indicates the effect of organic mulch on the fruit yield and yield components of sweet pepper in the rainy season. Number of fruits per plant, yield per plant, total yield, mean fruit weight, length and diameter were not significantly influenced by any of the four treatments. The effect of organic mulch on yield and yield components of sweet pepper in the dry season is shown in table 4.9. The mulch treatments produced significantly higher weight of fruits per plant, total fruit yield and mean fruit weight than the control plants. For instance, dry rice husks, empty palm fruit bunches and cocoa pods mulches increased weight of fruits per plant over the control plots by 334%, 200% and 189.9% respectively. Fruit number per plant, mean fruit length and mean fruit diameter were not significantly influenced by any of the four treatments. Rice husk mulch produced significantly higher weight of fruits per plant than palm fruit bunch mulch and cocoa pod husk mulches. Empty palm fruit bunch mulch recorded no significant increase in fruits weight per plant over cocoa pod husk mulch. Furthermore, there were no significant increases in total fruit yield and mean fruit weight among the mulch treatments. University of Ghana http://ugspace.ug.edu.gh 37 Table 4.8: Effect of organic mulch on yield and yield components of sweet pepper in the rainy season Mulch Fruit number Weight Total Mean Fruit Fruit type per plant of fruits per fruits yield fruit weight length width plant(g) (t/ha) (g) (cm) (cm) Rice husk 1.35 30.8 0.38 13.5 5.06 5.09 Palm fruit bunches 1.45 28.3 0.349 11.0 4.68 5.28 Cocoa pod husk 1.20 26.5 0.327 13.1 4.61 4.44 Control 1.45 36.9 0.456 13.8 6.72 5.75 LSD (5%) NS NS NS NS NS NS Table 4.9: Effect of organic mulch on the yield and yield components of sweet pepper in the dry season Mulch Fruit number Weight Total Mean Fruit Fruit type per plant of fruits per fruits yield fruit weight length width plant(g) (t/ha) (g) (cm) (cm Rice husk 5.0 159.3 1.97 27.9 3.96 4.06 Palm fruit bunches 4.0 110.1 1.40 21.9 3.68 3.57 Cocoa pod husk 4.0 106.0 1.31 23.9 4.01 3.75 Control 3.0 36.7 0.45 12.5 3.10 3.02 LSD (5%) NS 47.02 705.59 6.84 NS NS 4.7 Mean number and weight of marketable and unmarketable fruits Table 4.10 shows data on mean number and weight of marketable and unmarketable fruits of sweet pepper in the rainy season. Data in Table 4.10 indicates that there were no significant University of Ghana http://ugspace.ug.edu.gh 38 differences in mean number of marketable fruits among the treatments. Similarly, the mean number of unmarketable fruits were not significantly influenced by any of the treatments.The mulched plots produced significantly higher mean weight of marketable fruits compared to the control. For instance, dry rice husk, empty palm fruit bunch and cocoa pod mulches enhanced mean weight of marketable fruits over the control by 176%, 72% and -19% respectively. Rice husk mulch recorded significant increase in mean weight of marketable fruits over empty palm fruit bunch and cocoa pods husk mulches but there was no significant increase in mean weight of marketable fruits among palm fruit bunch and cocoa pods husk mulches. However, none of the treatments significantly influenced the mean weight of unmarketable fruits. Table 4.11 indicates the effect of organic mulch on mean number and weight of marketable and unmarketable fruits of sweet pepper in the dry season. There were significant increases in mean number and weight of marketable fruits between the mulched plots and the control. For instance, dry rice husks, empty palm fruit bunches and cocoa pods increased marketable fruits yield per plant over the control plots by 1394%, 791% and 703% respectively. Rice husk mulch recorded significant increase in mean number of marketable fruits over cocoa pod husk mulch but showed no significant increase in mean number of marketable fruits over empty palm fruit bunch mulch. There was no significant increases in the mean number of marketable fruits among empty palm fruit bunch and cocoa pod husk mulches. Rice husk recorded significant increase in mean weight of marketable fruits over empty palm fruit bunch and cocoa pod husk. There was no significant difference in mean weight of marketable fruit between the empty palm fruit mulch and cocoa pod husk mulch. There were no significant differences in the mean number and weight of unmarketable fruits between the mulched plots and the control. University of Ghana http://ugspace.ug.edu.gh 39 Table 4.10: Effect of organic mulch on mean number and weight of marketable fruits and mean number and weight of unmarketable fruits of sweet pepper in the rainy season Mulch Mean number Mean number Mean weight Mean weight Type of marketable of unmarketable of marketable of unmarketable Fruits/plant fruit/plant fruits/plant (g) fruits/plant(g) Rice husk 1 0 35.6 11.4 Palm fruit bunches 1 1 22.2 13.1 Cocoa pod 0 1 10.5 8.8 Control 1 1 12.9 10.7 LSD (5%) NS NS 12.26 NS Table 4.11: Effect of organic mulch on mean number and weight of marketable fruits and mean number and weight of unmarketable fruits of sweet pepper in the dry season Mulch Mean number Mean number Mean weight Mean weight Type of marketable of unmarketable of marketable of unmarketable Fruits/plant fruits/plant fruit/plant (g) fruits/plant (g) Rice husk 4.35 0.50 147.90 33.70 Palm fruit bunches 3.20 1.10 88.20 16.10 Cocoa pod husk 2.50 1.50 79.50 23.40 Control 0.45 2.20 9.90 26.80 LSD(5%) 1.63 NS 54.89 NS 4.8 Soil moisture content The effect of organic mulch on soil moisture content in the rainy season is shown in Table 4.12. There was no significant difference in soil moisture content among the different treatments. Cocoa pod husk however, recorded the highest amount of soil moisture followed by empty palm fruit bunch and rice husk. University of Ghana http://ugspace.ug.edu.gh 40 In the dry season soils under mulch treatments retained si