Department of Crop Science

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18S and ITS1 genomic sequence variations in Rotylenchulus reniformis isolates from Alabama
(Journal of Cotton Science, 2013-01) Nyaku, S.T.; Kantety, R.V.; Tilahun, Y.; Lawrence, K.S.; Soliman, K.M.; Cebert, E.; Sharma, G.C.
Upland cotton, Gossypium hirsutum L., is highly susceptible to infection by reniform nematode (Rotylenchulus reniformis), which can cause over 10% reduction of cotton yields in Alabama. Detection of reniform nematode (RN) and analysis for molecular variation within its population is important for understanding its interactions with cotton and other host plant species. Restriction analysis of PCR products of ITS1 regions was achieved using four restriction enzymes, HaeIII, HhaI, MspI, and RsaI. These showed similar banding patterns for both male and female populations. However, MspI digestion of ITS1 amplification products showed variants within the combined sex and location effects primarily attributed to a 500 bp fragment that was absent in other restriction digestions. Intra-nematodal variations in 18S and ITS1 rDNA were studied in detail by sequencing a minimum of ten clones in each individual male and female RN isolates in both directions. Multiple sequence alignment of the 18S rDNA sequences showed two major types of sequences within this gene for both male and female RN clones, which could be distinguished at 27 specific sites. Two distinct ITS1 fragments of lengths (550 bp and 720 bp) were observed; referred to as ITS1S and ITS1L respectively. Neighbor-joining analysis was used in revealing the relationships and grouping characteristics between male and female RN clones, with clones grouping together irrespective of sex and isolate. Sequencing of one-third of the 18S and ITS1 rDNA regions provided clear evidence of intra-and inter-nematode variability, in addition to gene conversion events in the 18S rDNA of individual male and female RN clones. © The Cotton Foundation 2013.
Ability of the larval ectoparasitoid Habrobracon hebetor (Say, 1836) (Hymenoptera: Braconidae) to locate the rice moth Corcyra cephalonica (Stainton, 1865) (Lepidoptera: Pyralidae) in bagged and bulk stored rice [Wirtsfindung des larvalparasitoiden habrobracon hebetor (say, 1836) (Hymenoptera: Braconidae) in gesacktem und geschüttetem reis gegenüber der reismotte Corcyra cephalonica (Stainton, 1865) (lepidoptera: Pyralidae)]
(Journal of Plant Diseases and Protection, 2010-04) Adarkwah, C.; Büttner, C.; Reichmuth, C.; Obeng-Ofori, D.; Prozell, S.; Schöller, M.
The potential of using Habrobracon hebetor for the inundative biological control of Corcyra cephalonica in rice stored in jute bags and in bulk was assessed. Host-finding in the situation of bag storage was tested by preparing small jute bags measuring 18 × 16 cm filled with 5 kg of un-infested rice grains. In the first experiment, 60 larvae of C. cephalonica were released into the bag. The bag was placed in an empty climatized room with an area of 12.3 m2. Sixty H. hebetor adults (sex ratio of 1 male: 2 females) were released at a distance of 1.6 m away from the jute bag. The number of H. hebetor adults that entered the jute bag was counted daily for 8 days by opening the bag and counting the parasitoids. Only 3% of the parasitoids entered the jute bag. In a second experiment, 60 C. cephalonica larvae were placed inside a wire gauze cage within the jute bag. Ten H. hebetor adults were released into the jute bag. The bag was sealed. After 1 week the cage was removed, and the number of C. cephalonica as well as F1 generation of H. hebetor that emerged was recorded. H. hebetor was able to significantly reduce the number of C. cephalonica emerging from the bagged rice; the corrected mortality due to the parasitoid release was 92.13%. The emergence of H. hebetor progeny started on day 9 after the introduction of the parasitoids and continued until day 21. Host-finding in the situation of bulk rice was tested in glass cylinders (50 cm height, Ø = 25 cm) containing caged larvae at horizontal depths of 7 and 14 cm. H. hebetor was able to find its host C. cephalonica in both depths; significantly more F1 H. hebetor adults emerged from hosts placed 7 cm deep. The implications of these results with respect to the suitability of H. hebetor for the biological control of C. cephalonica in bagged and bulk rice are discussed. © Eugen Ulmer KG, Stuttgart.
African weaver ant-produced semiochemicals impact on foraging behaviour and parasitism by the Opiine parasitoid, Fopius arisanus on Bactrocera invadens (Diptera: Tephritidae)
(Biological Control, 2014-12) Appiah, E.F.; Ekesi, S.; Afreh-Nuamah, K.; Obeng-Ofori, D.; Mohamed, S.A.
The fruit fly, Bactrocera invadens is an alien invasive pest of mango in Africa. The predatory African weaver ant, Oecophylla longinoda is being promoted for managing B. invadens and classical biological control with the Opiine parasitoid, Fopius arisanus is also underway. The current study investigated interactions between these two natural enemies. Specifically we assessed whether semiochemicals deposited by the ant on leaves and fruit affected the landing behavior of F. arisanus, its patch residence time and subsequent parasitism rates. Results showed that significantly more F. arisanus landed on 'ant-unexposed' leaves and fruits (leaves: 3.8 ± 0.5-7.7 ± 0.8; fruits: 4.1 ± 0.1-8.1 ± 1.2) compared with 'ant-exposed' leaves and fruits (leaves: 0.4 ± 0.1-2.5 ± 0.3; fruits: 0.2 ± 0.1-2.8 ± 0.7) from mango, citrus, guava and avocado. Parasitoid patch residence times were significantly longer on 'ant-unexposed' mango fruits (654.2 ± 28.4. s-1034.2 ± 112.6. s) compared to 'ant-exposed' fruits (75.2 ± 18.4. s-144.8 ± 42. s) regardless of whether eggs of B. invadens were present. In terms of percent parasitism, F. arisanus achieved significantly higher parasitism rates in B. invadens from 'ant-unexposed' mango fruits (72.8 ± 3.8) compared with 'ant-exposed' fruits (18.2 ± 1.8). Regression analysis showed a significant inverse relationship between the duration of exposure of mango fruits to ant-produced semiochemicals and the number of F. arisanus adults landing on fruits and percent parasitism. In field cages, 32% parasitism of B. invadens was achieved in mango fruits on trees without ants and 11% in mango fruits on ant-infested trees. These results suggest the potential for biotic interference between the two natural enemies if they are recommended for use within the same ecosystem. © 2014 Elsevier Inc.
Application of non-thermal pretreatment techniques on agricultural products prior to drying: a review
(Journal of the Science of Food and Agriculture, 2020-01-23) Essilfie, G.; Osae, R.; Alolga, R.N.; Akaba, S.; Song, X.; Owusu-Ansah, P.; Zhou, C.
BACKGROUND: Most agricultural crops contain high moisture content (80–95% wet basis (wb)) which makes them very susceptible to microbial damage leading to shorter shelf-life and high postharvest losses. The high perishability of these agricultural products requires preservation techniques to prolong their shelf-lives. Drying remains an important component of processing in this regard. Therefore, any pretreatment methods for drying agricultural product that decreases the moisture content and minimizes drying time by conserving the quality of the crop product is of prime significance. This article is a comprehensive review of recent developments of non-thermal pretreatment (NTP) methods. A summary of their significance, emerging and innovative methods of this technology together with its applications and limitations are discussed. This article further examines the environmental impact of NTP techniques. RESULTS: NTP techniques, such as high pressure, ultrasound, pulsed electric field and osmotic dehydration methods are essential operations for pre-dehydration of agricultural products prior to drying. These techniques can avoid the deleterious effects of heat on nutritive value, colour and flavour of agricultural products compared to thermal pretreatments. They also enhance the inactivation of the enzymes, improve energy efficiency and mass transfer, reduce processing time, preserve bioactive compounds, improve drying kinetics and drying rate, minimize enzymatic browning, and enhance product quality. CONCLUSION: These findings will provide a better understanding of different NTP methods and also make available more information for selecting pretreatment techniques for drying of agricultural products.
Assessing the effectiveness of a local agricultural research committee in diffusing sustainable cocoa production practices: The case of capsid control in Ghana
(International Journal of Agricultural Sustainability, 2007-01) Ayenor, G.K.; Röling, N.; Van Huis, A.; Padi, B.; Obeng-Ofori, D.
The conventional method of ‘delivering’ technologies recommended by researchers to farmers through extension has proved ineffective, resulting in a persistent low (3.5% over ten years) adoption of research-based cocoa technologies. The present study was conducted in the Eastern Region of Ghana and assessed the impact of the Local Agricultural Research Committee (LARC) approach on the diffusion of capsid management knowledge and practices, developed with the LARC, to others in the community. Capsids (Sahlbergella singularis and Distantiella theobroma) were diagnosed as the most serious production constraint. LARC members engaged in intensive interactive learning and experimentation to control them. The interactive approach developed by the International Centre for Tropical Agriculture was used to link the LARC with community farmers, a majority of whom aspired to produce organic cocoa for a premium. The LARC acquired vital agro-ecological knowledge on capsid management, including skills in scouting for capsids to determine their temporal distribution and systematic experimentation with control methods, before presenting its results to the community. This article reports on a survey comparing three categories of farmers: LARC members, exposed and non-exposed community farmers, so as to assess the diffusion and impact of LARC knowledge co-production. The results show that the LARC approach significantly influenced acquisition and diffusion of knowledge and practices. © 2007 Taylor & Francis Group, LLC.
Assessing the nutritional quality of stored grain legume fodders: Correlations among farmers’ perceptions, sheep preferences, leaf-stem ratios and laboratory analyses
(Small Ruminant Research, 2022) Akakpo, D.B.; de Boer, I.J.M.; Giller, K.E.; Adjei-Nsiah, S.; Duncan, A.J.; Oosting, S.J.
Crop residues have the potential to alleviate annual feed shortages and nutrient deficiencies experienced in the dry season in the savanna zones of West Africa. Farmers in West Africa especially value the residues of grain legumes, also known as grain legume fodders (GLFs), as animal feed. In this study, therefore, we assessed the nutritional quality of GLFs as affected by storage conditions using four different methods: farmers’ perception score (FPS), sheep preference score (SPS), leaf-to-stem ratio (LSR), and laboratory analysis of organic matter digestibility (OMD), crude protein content, neutral detergent fibre (NDF) and acid detergent fibre (ADF). We also determined correlations among these variables. The fodder of cowpea, groundnut and soybean were stored separately in three locations (rooftop, room and treefork) and with two packaging types (polythene sacks or tied with ropes) for 60, 90 and 120 days. FPS was determined by scoring the perceived quality of GLFs on a scale of 1–10 (1 = bad and 10 = good) based on physical characteristics by a group of farmers. SPS was assessed by a cafeteria feeding trial based on dry matter intake of GLFs by a flock of 12 sheep per village during a 14 hr period. LSR was determined based on the mass of the botanical fractions, i.e. leaf (leaf blade only) and stem (stem and petioles) of 200 g samples separated carefully by the hand. Laboratory analysis was done by near-infrared spectroscopy (NIRS). Results showed that all quality assessment methods successfully discriminated GLF quality differences among crops. Only farmers and sheep could distinguish quality differences among all storage conditions and packing types, whereas laboratory analyses methods could not. These findings could be due to the fact that farmers use LSR to evaluate feed quality, though colour, texture and smell of the fodder could also contribute. We also found significant correlations (ranging from 0.35 to 0.88) between all the quality assessment methods across all treatments. There were few within crop correlations between the fodder quality assessment methods, i.e. only FPS and LSR for groundnut and cowpea, FPS and CP for groundnut and all laboratory analyses parameters among each other for all crops. Hence, the differences among crops were the important determinants of the correlations. From this study, we conclude that farmers have experience and knowledge about nutritional quality of feed and livestock preference for feed. Development programmes and projects could benefit from using such knowledge when formulating and implementing interventions.
Assessment of genetic diversity among African cassava Manihot esculenta Grantz accessions resistant to the cassava mosaic virus disease using SSR markers
(Genetic Resources and Crop Evolution, 2006-11) Lokko, Y.; Dixon, A.; Offei, S.; Danquah, E.; Fregene, M.
A study was conducted to determine the extent of genetic diversity among African cassava (Manihot esculenta Crantz) accessions resistant to the cassava mosaic virus disease (CMD), using simple sequence repeat (SSR) markers. The accessions included a breeding stock (clone 58308), five improved lines, 62 CMD resistant and 10 CMD susceptible landraces. Genetic diversity was assessed among accessions in five cluster groups derived from UPGMA analysis on data from 18 SSR primer pairs. Average gene diversity, He, was high in all cluster groups, with an average heterozygosity of 0.591 ± 0.061. The estimator of inbreeding Fis revealed a low level of inbreeding within groups and averaged -0.262 ± 0.142. Gene diversity among all accessions was 51.4% and gene diversity within cluster groups was 46.6%, while 4.8% was due to diversity between the different cluster groups. The amount of genetic differentiation measured by Gst and Fst were 9.6% and 12.1% respectively, indicating a weak genetic structure. © 2006 Springer Science+Business Media, Inc.
Assessment of grain yield losses in pearl millet due to the millet stemborer, Coniesta ignefusalis (Hampson)
(Insect Science and its Application, 2003-09) Drame-Yaye, A.; Youm, O.; Ayertey, J.N.
Studies were conducted at the ICRISAT Sahelian Centre, Niger, to assess damage and yield loss by the millet stemborer, Coniesta ignefusalis (Lepidoptera: Pyralidae) on Pennisetum glaucum (L.) R. Brown. Although 78% of stems were infested, late attack by the millet stemborer on millet plants resulted in bored stems yielding more than unbored ones. Artificial infestations with 5 and 10 larvae per plant at 2 weeks after plant emergence (WAE) resulted in 50 to 70% plants with deadhearts and 24 to 100% avoidable yield loss. At 4 weeks after plant emergence, infestations with 5 larvae and 10 larvae per plant resulted in 7% increase in yield and 16% yield loss, respectively. Therefore, both the age of plant and density of borer population at the time of infestation can influence resulting stemborer damage and yield loss on pearl millet. © 2003 ICIPE.
Assessment of storability of two maize cultivars in a hermetic triple layer biodegradable bag
(Acta Horticulturae, 2015-02) Ansah, F.A.; Fatunbi, A.O.; Adekunle, A.A.; Obeng-Ofori, D.; Afreh-Nuamah, K.; Anankware, J.P.; Badu, A.S.
Storage of maize is very important for food security, especially in developing countries; like Ghana. However, several abiotic and biotic factors cause considerable losses during its storage. Therefore, the work studied the effectiveness of hermetic triple layer biodegradable bags (HTLBB) and polypropylene interwoven bags (PIB) in reducing losses of stored maize. Experiments were conducted in a small holder farmer storage crib and in a laboratory. A factorial combination of HTLBB, PIB and maize cultivars, improved 'Obatanpa' and local 'Denkye' were used. The samples were stored for six months at an average temperature of 27°C and 58% RH. The moisture content, hidden infestation, weight loss, germination capacity and colour were assessed. A significant increase in the moisture content of both cultivars (12.4-15.4%) was found in HTLBB-stored samples probable due to airtight conditions and the respiratory activities of grains, while in PIB no significant differences were found (12.4-12.9%). Laboratory and field assessment of percentage germination and emergence was higher in 'Obatanpa' than in 'Denkye'. However, HTLBB-stored samples, kept 90% of germination capacity while in PIB-stored, a maximum of 60%. Weight losses were also lower in HTLBB-stored 'Obatanpa' and 'Denkye' at 7.4 and 3.8% than PIB-stored at 15.1 and 9% respectively, attributable to varietal type and hidden infestation. Colour changes were observed in both storage bags which were related to possible increase in carotenoid content during storage. As main conclusion, HTLBB has the potential to protect stored maize better than PIB without any chemical treatment; provided its moisture content is very low.
Bio-activities of powders four plants against Prostephanus Truncatus Horn. (Coleoptera: Bostrichidae) and Tribolium Castaneum Herbst (Coleoptera: Tenebrionidae)
(West African Journal of Applied Ecology, 2014) Buxton, T.; Eziah, V.Y; Owusu, O.
The effect of the dry powders of the roots and leaves of Ocimum canum, Zanthoxylum xanthoxyloides, Moringa oleifera and Securidaca longipedunculata on the survival of Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae) and Tribolium castaneum Herbst (Coleoptera: Tenebrionidae) was determined in the laboratory. Generally, all the plant materials exhibited various levels of bio efficacies, with Z. xanthoxyloides and S. longipedunculata exhibiting the highest potency. Percentage survivorship of 35% and 40% were recorded for the roots and leaves, respectively, of Z. xanthoxyloides against T. casteeneum while 20% and 30% were recorded for roots and leaves of S. longipedunculata, respectively, against P.tuncatus.
Bio-rational control of red flour beetle Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) in stored wheat with Calneem® oil derived from neem seeds
(Journal of Pest Science, 2010-09) Adarkwah, C.; Obeng-Ofori, D.; Büttner, C.; Reichmuth, C.; Schöller, M.
The red flour beetle, Tribolium castaneum (Herbst), is one of the most serious secondary pests that feeds on a wide range of durable stored products including cereals, cereal products and other high value produce such as cocoa beans and dried fruits. Toxicity and protectant potential of Calneem® oil derived from the seeds of the neem tree Azadirachta indica A. Juss. towards T. castaneum were evaluated in stored wheat in the laboratory using contact toxicity, grain treatment, persistency, progeny emergence and repellency assays. Calneem® contains about 0.3% azadirachtin as its major active ingredient. The Calneem® was applied at six dosages (0.1, 0.2, 0.5, 1.0, 2.0 and 3.0% v/v). The oil was emulsified with water using 0.07% soap. All dosages of Calneem® oil were toxic and highly repellent to T. castaneum with an overall repellency in the range of 52-88%. The highest dosage of 3.0% of Calneem® oil tested killed at least 90% of the beetles within 72 h on grain, and 88% mortality was obtained on filter paper. T. castaneum mortality was dose dependent. The development of eggs to adults on cracked wheat was significantly (P > 0.05) inhibited by Calneem® oil treatments. The effectiveness of Calneem® oil was significantly reduced by the length of storage after application. The results obtained suggest good potential for the practical use of Calneem® oil as grain protectant for stored product pest control. The use of plant materials such as neem oil may be a safe, cost-effective method of grain preservation against pest infestation amongst low-resource poor farmers who store small amounts of grains. © 2010 Springer-Verlag.
Biochemical mechanisms of insecticide resistance in the diamondback moth (DBM), Plutella xylostella L. (Lepidopterata: Yponomeutidae), in the Sydney region, Australia
(Australian Journal of Entomology, 2009-11) Eziah, V.Y.; Rose, H.A.; Wilkes, M.; Clift, A.D.
Following the detection of resistant diamondback moth (DBM) populations to synthetic pyrethroid, organophosphorus and indoxacarb insecticides in the Sydney Basin, a study of the major biochemical mechanisms was conducted to determine the type of resistance in these populations. The activity of cytochrome P450 monooxygenases increased two- to sixfold when compared with the susceptible strain. Up to a 1.9-fold increase in esterase activity in resistant strains compared with the susceptible strain was observed. In vitro inhibition studies showed that profenofos, methamidophos and chlorpyrifos strongly inhibited the esterases while permethrin and esfenvalerate resulted in less than 30% inhibition. Qualitative analysis of the esterases using native polyacrylamide gel electrophoresis showed four bands in both the susceptible and resistant individuals with more intense staining in the resistant individuals. The development of these bands was inhibited by methamidophos and chlorpyrifos pretreatment of the protein extract while permethrin and esfenvalerate did not exhibit this effect. Glutathione S-transferase (GST) activity was significantly higher in two field populations compared with the remaining populations. Overall, the study showed that the mechanisms of insecticide resistance in the DBM populations in the area studied were due to cytochrome P450 monooxygenases, esterase and GSTs, and possibly other non-metabolic mechanisms that were not investigated in the present study. © 2009 Australian Entomological Society.
Bioefficacy of Zanthoxylum xanthoxyloides and Securidaca longependuncata against Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae) and Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae)
(Journal of Biopesticides, 2013-01) Eziah, V.Y.; Buxton, T.; Owusu, E.O.
Prostephanus truncatus Horn (Coleoptera: Bostrichidae) and Tribolium castaneum Herbst (Coleoptera: Tenebrionidae) are two important stored product insect pests found in most storage warehouses. Their activities tend to reduce the viability and the nutritive values of seeds and grains. In this study the bio-efficacy of Zanthoxylum xanthoxyloides and Securidaca longependuncata against P. truncatus and T. castaneum was investigated. The biological effects of methanol extracts of dry roots and leaves of Z. xanthoxyloides and the roots of S. longependuncata at 0.25 g mL-1, 0.5 g mL-1, 1.0 g mL-1 and 2.0 g mL-1 on the two beetle species were determined in the laboratory using dipping, grain treatment, progeny emergence, repellency and grain damage assessment assays. Adult mortality by dipping ranged between 80% and 100% in both insects for the plants extracts. There was no survival recorded at 2.0 g mL-1 of Z. xanthoxyloides roots and leaves and S. longepedunculata roots for both insects in treated grains. Also, no adult emerged in grains treated with 2.0 g mL-1 of the Z. xanthoxyloides roots while the same concentration of S. longepedunculata resulted in only 2% adult emergence for both insects. The methanol extracts of the two plants yielded various levels of repellency against the insects. 2.0 g/mL-1 of the Z. xanthxyloides roots yielded the highest repellency of 90.0 ± 9.5 % and 100 ± 0.0% against P. truncatus and T. castaneum respectively. Grains treated with plant extracts significantly reduced damage caused by P. truncatus and T. castaneum compared with the untreated grains. © JBiopest 370.
Can yield variability be explained? Integrated assessment of maize yield gaps across smallholders in Ghana
(Field Crops Research, 2019-03-29) Adjei-Nsiah, S.; van Loon, M.P.; Descheemaeker, K.; Akotsen-Mensah, C.; van Dijk, M.; Morley, T.; van Ittersum, M.K.; Reidsma, P.
Agricultural production in Ghana should more than double to fulfil the estimated food demand in 2050, but this is a challenge as the productivity of food crops has been low, extremely variable and prone to stagnation. Yield gap estimations and explanations can help to identify the potential for intensification on existing agricultural land. However, to date most yield gap analyses had a disciplinary focus. The objective of this paper is to assess the impact of crop management, soil and household factors on maize (Zea mays) yields in two major maize growing regions in Ghana through an integrated approach. We applied a variety of complementary methods to study sites in the Brong Ahafo and Northern region. Farm household surveys, yield measurements and soil sampling were undertaken in 2015 and 2016. Water-limited potential yield (Yw) was estimated with a crop growth simulation model, and two different on-farm demonstration experiments were carried out in 2016 and 2017. There is great potential to increase maize yields across the study sites. Estimated yield gaps ranged between 3.8 Mg ha−1 (67% of Yw) and 13.6 Mg ha−1 (84% of Yw). However, there was no consistency in factors affecting maize yield and yield gaps when using complementary methods. Demonstration experiments showed the potential of improved varieties, fertilizers and improved planting densities, with yields up to 9 Mg ha−1. This was not confirmed in the analysis of the household surveys, as the large yield variation across years on the same farms impeded the disclosure of effects of management, soil and household factors. The low-input nature of the farming system and the incidence of fall armyworm led to relatively uniform and low yields across the entire population. So, farmers’ yields were determined by interacting, and strongly varying, household, soil and management factors. We found that for highly variable and complex smallholder farming systems there is a danger in drawing oversimplified conclusions based on results from a single methodological approach. Integrating household surveys, crop growth simulation modelling and demonstration experiments can add value to yield gap analysis. However, the challenge remains to improve upon this type of integrated assessment to be able to satisfactorily disentangle the interacting factors that can be managed by farmers in order to increase crop yields.
Canonical discriminant analysis of Rotylenchulus reniformis in Alabama
(Nematropica, 2013-01) Nyaku, S.T.; Kantety, R.V.; Lawrence, K.S.; Van Santen, E.; Sharma, G.C.
The reniform nematode, Rotylenchulus reniformis, infests over 300 plant species worldwide and over the last two decades it has emerged as a major cotton pest in the southeastern United States. Nine locations in Alabama and one location in Mississippi were selected for study of R. reniformis. Thirteen morphometric measurements were made on 20 male and 20 female nematodes from each population. The sex and location interaction was significant (P < 0.005) for all traits except total body length (P = 0.29) and the derived ratio trait a (body length / maximum body width, P = 0.06). Canonical discriminant analysis effectively separated the 10 sampling locations into three distinct groups; among them, Group 1 and 3 were distinct with an intermediate group (Group 2) differentiating in the middle. Furthermore, both female and male R. reniformis based on the morphometrics measured here adhered to this metrics-based grouping. Belle Mina (Limestone County, AL), Huxford (Escambia County, AL), and Mississippi State University, MSU (Oktibbeha County, MS) locations were separated from the remaining seven locations based on the large positive CAN1 centroid means. Eight out of 13 traits had high phenotypic correlations (r > 0.80) with CAN 1 for both sexes. Anal width and length of the hyaline portion of the tail measurement accounted for a significant amount (r > 80%) of the variation in total and sex-based canonical structure. Occurrence of the three non-overlapping morphometric groups in cotton-growing fields in close proximity (250 mile radius) suggests a greater biological variation in this species than expected. Cotton cultivars with differential resistance and soil types are among the major factors to be tested for further delineating the causes of morphometric variation in R. reniformis.
Causes of low productivity of cocoa in Ghana: Farmers' perspectives and insights from research and the socio-political establishment
(NJAS - Wageningen Journal of Life Sciences, 2004-12) Dormon, E.N.A.; Van Huis, A.; Leeuwis, C.; Obeng-Ofori, D.; Sakyi-Dawson, O.
Ghana is a major producer of cocoa in the world and relies heavily on the crop for foreign exchange revenue. However, production declined since the mid-1960s, reaching its lowest level in 1983, Although production has increased consistently since the mid-1980s, it still is less than the level attained in the mid-1960s. The decline is partly a result of decreasing areas under cultivation. Another problem in cocoa production in Ghana is low yields per ha, which is attributed to the incidence of pests and diseases, a low producer price, and non-adoption of research recommendations. Based on the idea that current research and extension messages might insufficiently address farmers' actual problems and context, a diagnostic study was carried out to better understand farmers' views on the problems of cocoa production. The study was conducted in three villages in the Suhum-Kraboa-Coalter District, Eastern Region, Ghana. An action research approach was followed to gather and analyse qualitative data with the objective of stimulating collective action in subsequent research activities with the farmers. Low productivity was identified as the main problem and the causes were classified into biological and socio-economic factors. The biological factors include the incidence of pests and diseases, most of which have received extensive research attention in Ghana, and of epiphytes, which have been neglected. The socio-economic causes were indirect and include the low producer price and the lack of amenities like electricity, which leads to migration, with as a result labour shortages and high labour costs. From the study it can be concluded that the biological and socio-economic causes of low productivity are inter-related in such a manner that tackling them separately will not overcome the problem unless the socio-technical nature of the causes are recognized and tackled in a holistic way. In this context, current interventions by research and extension seem to ignore important aspects of the problematic situation. Although the study shows the relevance of using a diagnostic approach, it is argued that outcomes may be affected by various contextual factors, including stakeholder selection and the relationship between the researcher and the participants. Hence, the outcomes of a diagnostic study should be approached with care.
Characterization of a mutant population of cocoyam (Xanthosoma sagittifolium L. Schott)
(International Journal of Botany, 2006-02) Danquah, A.; Offei, S.K.; Blay, E.T.; Asare, E.; Danquah, E.Y.
A mutant population of cocoyam (Xanthosoma sagittifolium L. Schott) developed through gamma irradiation of shoot tips of cocoyam was evaluated in two field experiments. In the first experiment, four putative mutants, fifty irradiated clones and four non-irradiated clones were evaluated for morpho-agronomic diversity. Progeny derived from minisetts were characterised in a second experiment to establish repeatability of the distinctive characters of the putative mutants. Yields were exceptionally low and this was attributed to poor environmental conditions. The mutants showed a distinctive yellow cormel apex and yellow interior cormel colour. Out of seventeen morphological traits studied in the second experiment, ten were monomorphic. These were growth habit, petiole attachment, petiole surface glaucous, leaf pubescence, leaf variegation, leaf surface glossy (shining), leaf margin, number of collecting vein, position of collecting vein and shape of petiole in cross-section. The seven polymorphic traits were petiole colour, colour of vein on leaf surface, leaf shape, leaf margin colour, leaf surface colour, leaf sinus denuding and lamina orientation. The main differences in the polymorphic characters were between the mutants on one side and the irradiated (non mutants) and non-irradiated clones on another side. It will be interesting to determine whether the mutants have desirable agronomic characters. © 2006 Asian Network for Scientific Information.
Classification of elite cassava varieties (Manihot esculenta Crantz) cultivated in Benin Republic using farmers’ knowledge, morphological traits and simple sequence repeat (SSR) markers
(Genetic Resources and Crop Evolution, 2018-02) Agre, A.P.; Bhattacharjee, R.; Rabbi, I.Y.; Alaba, O.A.; Unachukwu, N.N.; Ayenan, M.A.T.; Loko, Y.L.; Bauchet, G.J.; Dansi, A.
Cassava (Manihot esculenta Crantz) is an important food security crop or resource for poor rural communities particularly in Africa. The crop’s ability to produce high yields even under poor conditions and storability of its roots underground for longer periods or until needed makes it a model ‘food security crop’. In Benin Republic, cassava has been recognized as one of the major crop contributing towards dynamic value chains generating incomes for small-holder farmers. The crop is grown all over the country, however, the increased production are mainly recorded from far south and central parts of the country. Genetic improvement of cassava in Benin Republic is limited because of poor knowledge of genetic diversity present within the country. The main objective of this study was to assess the genetic diversity and relationships among elite cassava varieties collected from different regions of Benin using fluorescently labelled simple sequence repeat (SSR) markers and to compare the results with farmer’s knowledge and morphological traits. A total of 96 cultivars collected from major cassava growing areas such as Southern and Central Benin were classified into 24 different groups using farmers’ knowledge, while classification based on 18 morphological traits resulted in five groups. In total, sixteen SSR markers were tested for molecular analysis of the ninety-six cassava varieties. Among the sixteen, twelve SSR markers gave good banding pattern and were used to genotype the varieties. An average of 3.58 and 0.47 for number of alleles and polymorphism information content respectively was observed. The observed heterozygosity (Ho) ranged from 0.23 to 1.0 with an average of 0.66 indicating moderate level of diversity among the cultivars. Based on the proportion of shared alleles and hierarchical clustering, the 96 elite cassava varieties were classified as 74 unique varieties. Principal component analysis and analysis of molecular variance revealed no significant variation between the regions thus, explaining regular exchange of planting materials among cassava farmers across various regions. The moderate level of genetic diversity in famer’s field, revealed in the present study, is a good indication of the need for broadening the genetic base of cassava in Benin Republic and establishing a formal breeding program in the country.
Combined effects of shade and drought on physiology, growth, and yield of mature cocoa trees
(Science of the Total Environment, 2023) Mensah, E.O.; Ræbild, A.; Asare, R.; et al.
Climate models predict decreasing precipitation and increasing air temperature, causing concern for the future of cocoa in the major producing regions worldwide. It has been suggested that shade could alleviate stress by reducing radiation intensity and conserving soil moisture, but few on-farm cocoa studies are testing this hy pothesis. Here, for 33 months, we subjected twelve-year cocoa plants in Ghana to three levels of rainwater suppression (full rainwater, 1/3 rainwater suppression and 2/3 rainwater suppression) under full sun or 40 % uniform shade in a split plot design, monitoring soil moisture, physiological parameters, growth, and yield. Volumetric soil moisture (ϴw) contents in the treatments ranged between 0.20 and 0.45 m3 m− 3 and increased under shade. Rainwater suppression decreased leaf water potentials (ѱw), reaching − 1.5 MPa in full sun con ditions indicating severe drought. Stomatal conductance (gs) was decreased under the full sun but was not affected by rainwater suppression, illustrating the limited control of water loss in cocoa plants. Although pre dawn chlorophyll fluorescence (Fv/Fm) indicated photoinhibition, rates of photosynthesis (Pn) were highest in full sun. On the other hand, litter fall was highest in the full sun and under water stress, while diameter growth and carbon accumulation increased in the shade but was negatively affected by rainwater suppression. Abortion of fruits and damage to pods were high under shade, but dry bean yield was higher compared to under the full sun. The absence of interactions between shade treatments and rainwater suppression suggests that shade may improve the performance of cocoa, but not sufficiently to counteract the negative effects of water stress under field conditions.
Conidial mass production of entomopathogenic fungi and tolerance of their mass-produced conidia to UV-B radiation and heat
(Fungal Biology, 2023) Rangel, D.E.N,; Acheampong, M.A.; Bignayan, H.G.; et al.
We investigated conidial mass production of eight isolates of six entomopathogenic fungi (EPF), Apha nocladium album (ARSEF 1329), Beauveria bassiana (ARSEF 252 and 3462), Lecanicillium aphanocladii (ARSEF 6433), Metarhizium anisopliae sensu lato (ARSEF 2341), Metarhizium pingshaense (ARSEF 1545), and Simplicillium lanosoniveum (ARSEF 6430 and 6651) on white or brown rice at four moisture condi tions (75e100%). The tolerance of mass-produced conidia of the eight fungal isolates to UV-B radiation and heat (45 C) were also evaluated. For each moisture content compared, a 20-g sample of rice in a polypropylene bag was inoculated with each fungal isolate in three replicates and incubated at 28 ± 1 C for 14 days. Conidia were then harvested by washing the substrate, and conidial concentrations deter mined by haemocytometer counts. Conidial suspensions were inoculated on PDAY with 0.002% benomyl in Petri plates and exposed to 978 mW m 2 of Quaite-weighted UV-B for 2 h. Additionally, conidial suspensions were exposed to 45 C for 3 h, and aliquots inoculated on PDAY with benomyl. The plates were incubated at 28 ± 1 C, and germination was assessed at 400 magnification after 48 h. Conidial production was generally higher on white rice than on brown rice for all fungal species, except for L. aphanocladii ARSEF 6433, regardless of moisture combinations. The 100% moisture condition provided higher conidial production for B. bassiana (ARSEF 252 and ARSEF 3462) and M. anisopliae (ARSEF 2341) isolates, while the addition of 10% peanut oil enhanced conidial yield for S. lanosoniveum isolate ARSEF 6430. B. bassiana ARSEF 3462 on white rice with 100% water yielded the highest conidial production (approximately 1.3 1010 conidia g 1 of substrate). Conidia produced on white rice with the different moisture conditions did not differ in tolerance to UV-B radiation or heat. However, high tolerance to UV B radiation and heat was observed for B. bassiana, M. anisopliae, and A. album isolates. Heat-treated conidia of S. lanosoniveum and L. aphanocladii did not germinate.

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