Thesis (MSc. Agriculture (Agronomy)) --University of Limpopo, 2015 / Agronomic field trial was planted at two sites, Ukulima and Syferkuil, in Limpopo Province, to determine the response of cowpea to variable rates and methods of zinc application under supplementary irrigation and rainfed conditions, respectively. The experiment was laid out in a split plot arrangement and fitted into a randomized complete block design (RCBD). Treatments consisted of two factors namely zinc rates (0, 5, 10, 15, 20 and 25 kg ha-1) and methods of application (soil and foliar) with white cowpea variety (IT00K-1217) seeds sown. The zinc fertilizer was applied as ZnSO4 (38.5% Zn) while basal phosphorus (30 kg P ha-1) was applied in the form of single super phosphate (10.5% P) so as to eliminate P constraints. Soil application of the zinc fertilizer was band placed near the row of cowpea plant while foliar application was done 3-5 weeks after plant emergence. Growth parameters measured included plant height, number of primary branches, canopy cover, number of trifoliate leaves, days to 50% flowering and pod formation, and fresh biomass as well as yield component attributes. Twenty young cowpea leaves and immature green pods were each harvested at approximately 75% physiological maturity. Crude protein, total nitrogen, potassium, phosphorus, zinc, and iron content and uptake were assessed in the different plant parts. Growth, yield and nutrients data collected were subjected to analysis of variance. Treatments means were separated using Tukey’s test at probability level of 5%, while the response variables were modelled using quadratic polynomial equation. Results obtained revealed that total above ground biomass yield of 6219 kg ha-1 and fresh pod weight of 142.3 g were obtained when zinc was soil applied under rainfed condition compared to 6019 kg ha-1 and 138.0 g for total above ground biomass yield and fresh pod weight, respectively when foliar applied. Soil application gave a total above ground biomass yield of 6298 kg ha-1 and pod fresh weight of 150.9 g while foliar application gave total above ground biomass yield and pod fresh weight of 4791 kg ha-1 and 124.0 g, respectively at Ukulima. Soil application also gave a significantly higher grain yield (2251 kg ha-1) than the foliar application (1503 kg ha-1) at Ukulima. A higher but inconsequential effect on grain yield was obtained with soil over foliar application at Syferkuil. Application of zinc fertilizer at a rate beyond 5 kg ha-1 resulted in a grain yield reduction of up to 22.2% and 6.6% respectively at vi Ukulima and Syferkuil. Thus, this rate appeared optimum for both grain and fodder production when soil applied at both sites. Based on the quadratic model, total biomass (4897 kg ha-1) and grain (1602 kg ha-1) yields were optimized at an estimated zinc rate of 54.7 and 33.4 kg ha-1, respectively under supplementary irrigation, while total biomass (5913 kg ha-1) and grain (2696 kg ha-1) yields were obtained at an estimated optimum zinc rate of 20.1 and 26.8 kg ha-1, respectively under rainfed condition. A scorching effect of cowpea leaves was observed following foliar application of zinc fertiliser at 25 kg ha-1 that resulted in a decreased growth and yield at Ukulima. Foliar application resulted in improve cowpea leaf zinc concentration (43.9 mg kg-1) compared to soil application (23.2 mg kg-1) at Syferkuil. It also resulted in increased crude protein, total N, P, Fe and Zn uptake compared to soil application at Ukulima. Both soil and foliar zinc application gave 28.5% zinc concentration in the fresh immature pods samples collected. Findings from this study reveal that foliar zinc sulphate application resulted in higher grain and biomass yields as well as zinc concentration in the various cowpea plant parts. Based on the quadratic model used in this study, the optimum zinc rate required to guarantee high cowpea yield and zinc-rich grain and leaf content at both trial sites is highly variable; and thus requires further study for validation. Keywords: Cowpea production, grain yield, dryland farming, leafy vegetables, foliar fertilizer, improved nutrition, zinc deficiency.

Thesis (DTech. degree in Agriculture.)--Tshwane University of Technology, 2010. / Low soil N fertility accounts for poor crop yields in Africa. Additionally, chemical fertilizers use is inadequate due to high cost and unavalability. Because crops grown on such nutrient-poor soils are micronutrient deficient, incorporating N2-fixing legumes into cropping systems can sustainably improve crop yields and micronutrient capture. Nodulated cowpea easily forms symbioses with native rhizobial species, and can potentially fix atmospheric N2 into ecosystems. These bio-fertilization/-fortification traits can increase crop yields and nutrient accumulation in edible plant organs. Field experiments conducted in Ghana and South Africa assessed N2 fixation in cowpea in 2005 and 2006 using the 15N natural abundance technique. The genotypes Vuli-1 and TVu11424 contributed 178 and 198 kg N ha-1 in 2005 and 2006, respectively at Wa. At Manga, IT84S-2246 and TVu11424 fixed 157 and 171 kg N.ha- 1 in 2005 and 2006, while Fahari and IT84S-2246 contributed 182 and 131 kg N ha-1 in 2005 and 2006 respectively, at Taung. The effect of genotype x environment interaction on plant growth and N2 fixation were evaluated at Wa and Manga in Ghana, and Taung in South Africa. Whole-plant dry matter was highest at Manga relatve to Taung. The G x E interaction was significant for biomass yield, symbiotic parameters and grain yield. Fahari produced 3.2 and 2.2- fold more biomass at Manga than at Wa and Taung respectively. All the 25 genotypes derived significantly higher levels of N nutrition from symbiotic fixation at Taung compared to Manga and Wa. vi The relationship between symbiotic N nutrition and photosynthetic carbon assimilation in young fully expanded leaves of cowpea was assessed in Ghana, in 2005 and 2006. Benpila, Glenda, IT86D-1951 in 2005, and Sanzie in 2006, showed high photosynthesis, greater stomatal conductance, high transpiration, and increased water-use efficiency. Symbiotic N contribution was greater in Mchanganyiko, Ngonji and IT86D-2075 in 2005. These data show that where symbiotic legumes derive a large proportion of their N from N2 fixation, photosynthetic C yield is increased as a result of elevated Rubisco Analysis of edible leaves and grain of cowpea genotypes revealed significant differences in mineral concentration. Cowpea genotype IT82D-889 exhibited high concentrations of P, K, Ca, Mg and S. Iron concentration in cowpea grain was 137 μg.g-1 in Soronko, while Zn was 65 μg.g-1 in Vuli-1. Leaf concentrations of Cu, Mn, B and Fe were consistently higher in the genotypes Apagbaala, IT84S-2246, Fahari and IT97K-499-39. Compared with spinach, cowpea leaves had 3-fold more Fe which can offer biological solution to micronutrient deficiency in Africa.

An experiment was carried out at Redland Bay on the south-eastern coast of Queensland from (16/2/1991 to 27/6/1991) in an attempt to relate the performance of maize (Zea mays L.)/cowpea (Vigna unguiculata (L) Walp.) intercrops to radiation interception and to radiation availability to cowpea and to ascertain the effects of cowpea morphological characteristics. A quick maturing maize cultivar (DK529) and two cowpea cultivars (Red Caloona and 672330) were used. Changes in light availability to cowpea in intercrops were made by varying maize density. Three plant population densities were used: 22,000 plants ha^-1, 44,000 plants ha^-1, and 67,000 plants ha^-1. Both cowpea cultivars were very vegetative and vigorous in growth with little difference in their morphological characteristics. Cowpea cultivar 1 (Red Caloona) was however a better climber and retained green leaves for a longer duration. Increasing maize plant population density effectively reduced the amount of light reaching the cowpea canopy. Light availability was reduced to a minimum of 13% and 15% in the high maize plant population density and to a minimum of 47% and 42% in the low maize plant population density in cowpea cultivar 1 and 2 respectively. Intercropping reduced growth and yield of both cowpea cultivars through reductions in cowpea leaf area index (LAI), light interception and pod number. It also caused reductions in seed size in cowpea cultivar 2 (67233). Increasing maize plant population density further reduced all the above parameters. Maize growth and yield was affected by intercropping but to a lesser extent. Maize yields were reduced by 16% and 14% under cowpea cultivar 1 and cowpea cultivar 2 respectively, compared to an average reduction of 68% and 82% in cowpea cultivars 1 and 2 across the 3 maize plant population density. Radiation use efficiency (RUE) of the intercrops was lower than that of maize sole crop but higher than that of cowpea sole crop. Intercropping proved to be more advantageous in the vegetative stages of growth than in the reproductive stage except in the medium maize plant population density treatment. This was attributed to better light use efficiency in the early growth in intercrops than sole crops which was estimated to be between 1.1 and 2.9 time higher in intercrops than in sole maize in the first 20 days after sowing (DAMS) . Results indicated that LAI and leaf longevity had a large effect on radiation interception and use in cowpea. Cowpea cultivar 2 was better yielding in sole crop that cowpea cultivar 1 (954 Vs 621 Kgha^-1) but was more affected by intercrop (157 Vs Kgha^-1). An advantage of intercropping was only obtained in the medium maize plant population density intercrops. These were however small advantages (13% and 11%) in cowpea cultivar 2 and cultivar 1 respectively. Intercropping maize with these two cowpea cultivars would therefore be of advantage only, where the interest of the farmer is in the production of maize grain and cowpea leaf, wither for consumption, livestock feed or as green manure.

An experiment was carried out at Redland Bay on the south-eastern coast of Queensland from (16/2/1991 to 27/6/1991) in an attempt to relate the performance of maize (Zea mays L.)/cowpea (Vigna unguiculata (L) Walp.) intercrops to radiation interception and to radiation availability to cowpea and to ascertain the effects of cowpea morphological characteristics. A quick maturing maize cultivar (DK529) and two cowpea cultivars (Red Caloona and 672330) were used. Changes in light availability to cowpea in intercrops were made by varying maize density. Three plant population densities were used: 22,000 plants ha^-1, 44,000 plants ha^-1, and 67,000 plants ha^-1. Both cowpea cultivars were very vegetative and vigorous in growth with little difference in their morphological characteristics. Cowpea cultivar 1 (Red Caloona) was however a better climber and retained green leaves for a longer duration. Increasing maize plant population density effectively reduced the amount of light reaching the cowpea canopy. Light availability was reduced to a minimum of 13% and 15% in the high maize plant population density and to a minimum of 47% and 42% in the low maize plant population density in cowpea cultivar 1 and 2 respectively. Intercropping reduced growth and yield of both cowpea cultivars through reductions in cowpea leaf area index (LAI), light interception and pod number. It also caused reductions in seed size in cowpea cultivar 2 (67233). Increasing maize plant population density further reduced all the above parameters. Maize growth and yield was affected by intercropping but to a lesser extent. Maize yields were reduced by 16% and 14% under cowpea cultivar 1 and cowpea cultivar 2 respectively, compared to an average reduction of 68% and 82% in cowpea cultivars 1 and 2 across the 3 maize plant population density. Radiation use efficiency (RUE) of the intercrops was lower than that of maize sole crop but higher than that of cowpea sole crop. Intercropping proved to be more advantageous in the vegetative stages of growth than in the reproductive stage except in the medium maize plant population density treatment. This was attributed to better light use efficiency in the early growth in intercrops than sole crops which was estimated to be between 1.1 and 2.9 time higher in intercrops than in sole maize in the first 20 days after sowing (DAMS) . Results indicated that LAI and leaf longevity had a large effect on radiation interception and use in cowpea. Cowpea cultivar 2 was better yielding in sole crop that cowpea cultivar 1 (954 Vs 621 Kgha^-1) but was more affected by intercrop (157 Vs Kgha^-1). An advantage of intercropping was only obtained in the medium maize plant population density intercrops. These were however small advantages (13% and 11%) in cowpea cultivar 2 and cultivar 1 respectively. Intercropping maize with these two cowpea cultivars would therefore be of advantage only, where the interest of the farmer is in the production of maize grain and cowpea leaf, wither for consumption, livestock feed or as green manure.

The purpose of the present study is to compare the growth-promoting properties of four varieties of the green cowpea: the blackeye, the red and white crowder, the brown crowder and the cream cowpea.

No description available.

No description available.

"February 2003" / Bibliography: leaves 160-174. / xi, 174 leaves : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / This study assessed separately the effects of Aluminium and of low pH on the growth of gigaspora margarita and its symbiotic function in the growth of cowpea (vigna unguiculata L. Walp,). / Thesis (Ph.D.)--University of Adelaide, Dept. of Soil and Water, 2003

Thesis (M.Sc.Agric.)(Agronomy)--University of Pretoria, 2009. / Abstract in English. Includes bibliographical references. Available on the Internet via the World Wide Web.

Abstract Although nodulated legumes have been used by indigenous peoples in Africa for centuries, their full potential has never been realized. With modern technology there is scope for rapid improvement of both plant and microbial germplasm. This review gives examples of some recent developments in the form of case studies; these range from multipurpose human food crops, such as cowpea (Vigna unguiculata (L.) Walp.), through to beverages (teas) that are also income-generating such as rooibos (Aspalathus linearis (Burm. f.) R. Dahlgren, honeybush (Cyclopia Vent. spp.), and the widely used food additive gum arabic (Acacia senegal (L.) Willd.). These and other potential crops are welladapted to the many different soil and climatic conditions of Africa, in particular, drought and low nutrients. All can nodulate and fix nitrogen, with varying degrees of effectiveness and using a range of bacterial symbionts. The further development of these and other species is essential, not only for African use, but also to retain the agricultural diversity that is essential for a changing world that is being increasingly dominated by a few crops such as soybean.