Cowpea (Vigna unguiculata (L.) Walp) is an important protein-rich grain legume of major economic importance. It is widely grown by small-scale farmers in the arid and semi-arid regions of the world where it is cultivated for its leaves, fresh immature pods and dry grains. However, it is also an underutilized grain legume. In sub-Saharan Africa where most of the cowpea is produced, drought stress is one of the major factors limiting its productivity. Despite the inherent capacity to survive drought stress, several cowpea varieties are affected by mid and late season drought. Therefore, varieties with a higher tolerance to drought stress are required to obtain higher and more stable yields. The objectives of this study were: (i) to determine morphological responses of four dual-purpose cowpea landraces to water deficits during vegetative and reproductive stages (ii) to determine physiological responses of four dual-purpose cowpea landraces to water deficits and recovery during the reproductive stage (iii) to determine yield performance of cowpea landraces after recovery from water stress and how this relates to (ii) above. Four cowpea landraces namely; Lebudu, Lehlodi, Sejwaleng and Morathathane collectedfrom Kgohloane and Ga-Mphela villages, Limpopo Province, South Africa were used in the study. Pot experiments were conducted under glasshouse conditions at the Controlled Environment Facility (CEF), University of KwaZulu-Natal. The first pot experiment evaluated the morphological responses of four cowpea landraces to water stress and recovery. The study was conducted as a single factor experiment laid out in randomized complete block design (RCBD). The treatments (four cowpea landraces) were each planted in 40 pots giving a total of 160 experimental units (drained polyethylene pots with a 5 litre capacity). Each plant in each pot was treated as a replicate. Plants were well-watered until the formation of six fully expanded trifoliates, then irrigation was withheld for 28 days to simulate drought stress during the vegetative growth. The imposition of drought stress was terminated by re-watering all plants after 28 days. The cowpea plants were re-watered sufficiently and allowed to grow until the four landraces reached 50% flowering stage. Watering was withheld again at 50% flowering for a two-week period for all the four landraces to simulate drought stress during the reproductive growth. The second experiment was conducted to investigate physiological responses of the four cowpea landraces to water stress during the reproductive stage. The experiment was laid out as a 4 x 2 factorial treatment structure in randomized complete design (CRD) with the following three factors: cowpea landraces – 4 levels (Lebudu, Lehlodi, Sejwaleng and Morathathane), water regimes – 2 levels (stressed and well-watered) treatment combinations each replicated 20 times (20 pots each containing one plant) giving a total of 160 experimental units (drained polyethylene pots with a 5 litre capacity). Data on morphological responses were collected and included: number of green vs. senesced leaves, visual assessment of leaf greenness, stem, branch greenness and survival percentage. Physiological responses to water stress were determined during the reproductive stage and included: leaf water potential, relative water content, stomatal conductance, proline content, chlorophyll content, carotenoid content, chlorophyll a content, phenolics (free and membrane-bound), total antioxidant capacity and chlorophyll fluorescence parameters (Fv/Fm). Genstat 14th edition (VSN International, UK) was used to perform analyses of variance (ANOVA) and differences between means were determined by the Least Significant Differences (LSD) at the 5% probability level. Landraces showed different morphological responses during both vegetative and reproductive growth stages. Lebudu, Lehlodi and Sejwaleng displayed a strong ability to maintain stem greenness longer as compared to Morathathane during vegetative growth. Lebudu delayed leaf senescence more than other landraces; no differences in survival were observed. All landraces survived for 28 days without water and resumed growth after re-watering. During the reproductive stage, Lebudu displayed a strong ability to maintain leaf, branches and stem greenness longer and showed relatively higher tolerance to drought stress compared to other three landraces. Water stress caused a decline in leaf water potential, relative water content, carotenoid content, chlorophyll content, stomatal conductance and increased proline content, phenolics, chlorophyll a content, total antioxidant capacity and while chlorophyll fluorescence parameter, Fv/Fm, was not affected. All landraces maintained higher relative water content above a critical threshold with Sejwaleng maintaining a significantly higher RWC (69%) than Lehlodi, Lebudu and Morathathane. Morathathane developed a more negative leaf water potential at maximum stress than Lebudu, Lehlodi and Sejwaleng. Stomatal closure was observed in all cowpea landraces during water stress, but re-opened after re-watering. Chlorophyll content was considerably reduced in Morathathane as compared to Lebudu, Lehlodi and Sejwaleng. No significant differences were observed between the cowpea landraces with respect to carotenoid content at maximum stress. Chlorophyll a content increased significantly for Morathathane as compared to Lebudu, Lehlodi and Sejwaleng. High accumulation of proline was observed for Lebudu, Lehlodi and Morathathane as compared to Sejwaleng, which showed a very slow accumulation of proline. Lebudu, Lehlodi and Sejwaleng showed an increase in phenolic compounds while a decline was observed for Morathathane. Total antioxidant capacity (TAOC) was high in all cowpea landraces during water stress. Also, all chlorophyll fluorescence parameters showed that cowpea landraces had efficient photo-protection mechanisms during drought stress. After re-watering, relative water content, leaf water potential, stomatal conductance, chlorophyll content, carotenoids, chlorophyll a, proline content and TAOC recovered and reached the same level as that of well-watered plants. All four landraces were re-watered after the imposition of stress and above ground biomass, pod mass and number and seed yield determined. Although there was a reduction in the total above-ground biomass, pod mass and number in all four landraces under water stress compared to the well–watered treatment; this was not statistically significant (P > 0.05). Furthermore, no significant differences (P > 0.05) were observed between the four landraces with respect to seed yield under stressed and well-watered conditions. This study established that cowpea landraces vary with respect to the various morphological and physiological adaptive mechanisms in response to water deficits. Such adaptive mechanisms probably ensure their survival under severe water stress conditions until the next rainfall and therefore allowing them to produce reasonably relatively higher leaf and seed yield. Detailed knowledge of these mechanisms in the landraces could be useful in the genetic enhancement and breeding for drought tolerance in the existing cowpea germplasm. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2013.

Introdução - Devido ao perfil de mortalidade e de danos patológicos associados, as doenças cardiovasculares são consideradas um sério problema de saúde pública. Níveis de colesterol plasmático elevados fazem parte dos fatores de risco mais importantes para o desenvolvimento dessas doenças. Pesquisas recentes demostraram que a proteína do feijão caupi promove a redução dos níveis de colesterol em hamsters e em seres humanos, possivelmente pela ação de peptídeos bioativos advindos da dieta. Entretanto, a via pela qual o colesterol é inibido por esses peptídeos, assim como os efeitos do processamento na ação biológica ainda são desconhecidos. Objetivo - Verificar a via de ação hipocolesterolêmica dos hidrolisados do feijão caupi e o efeito do processamento térmico nesta propriedade. Métodos - Parte da farinha integral foi submetida ao isolamento de proteína e o restante dos grãos foi submetido à cocção em autoclave e à extrusão. Após ser cozido em autoclave, o feijão cozido também teve sua proteína isolada. Posteriormente, a proteína isolada do feijão integral e do feijão cozido foi submetida à hidrólise in vitro. O processo de extrusão foi modelado em função da expansão dos extrusados segundo a metodologia de superfície de resposta. A farinha do feijão extrusado foi submetida à hidrólise enzimática in vitro sem isolamento prévio da proteína. Os três hidrolisados foram submetidos à ultrafiltração e a fração menor que 3 kDa foi utilizada nos ensaios de inibição da enzima 3-hidroxi-3-metilglutaril coenzima A redutase (HMGR) e no ensaio de inibição da solubilização micelar do colesterol para avaliar a ação dos hidrolisados na via hepática e na via entérica do metabolismo do colesterol respectivamente. Resultados - Os hidrolisados provenientes dos isolados proteicos apresentaram comportamentos semelhantes. Em doses mais elevadas de proteína (acima de 70 µg/mL), a inibição apresentou-se estável, por volta dos 75 por cento. Em relação ao hidrolisado da farinha de feijão extrusado, à medida que se aumenta a quantidade de proteína a capacidade inibitória diminui. Os hidrolisados foram capazes de inibir a solubilização micelar do colesterol de 5 a 39 por cento. O processamento térmico foi fator determinante para diminuir a solubilização do colesterol in vitro. Conclusão Os hidrolisados do feijão caupi são capazes de inibir a enzima HMGR e reduzir a solubilização micelar do colesterol in vitro, mesmo após o feijão ser processado termicamente. A capacidade dos hidrolisados de insolubilizar o colesterol foi melhorada pelo cozimento em autoclave e pela extrusão / Introduction- The cardiovascular diseases, due to mortality and associated pathological damage, are considered a serious public health problem. Elevated plasma cholesterol levels are part of the most important risk factors for the development of these diseases. Recent research indicated that Cowpea protein promotes the reduction of cholesterol levels in hamsters and humans, possibly by the action of bioactive peptides from the diet. However, the route by which cholesterol is inhibited by peptides, as well as the processing effects on biological action are still unknown. Objective - To verify the hypocholesterolemic pathway of hydrolyzed cowpea and the effect of thermal processing on this property. Methods - Part of wholemeal flour was subjected to isolation of protein, and the remaining of the grains was subjected to retort and extrusion cooking processes. After autoclaving the grain, protein was also isolated from the flour. Subsequently, the isolated protein from wholemeal and cooked flour was subjected to in vitro hydrolysis. The extrusion process was optimized according to response surface methodology using the expansion ratio of extrudates as the dependent variable. The extruded bean flour was subjected to in vitro enzymatic hydrolysis without the isolation of the protein. The three hydrolysates were subjected to ultrafiltration and and fractions smaller than 3 kDa was used for inhibition assays of the enzyme 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) and for inhibition assay of micellar solubilization of cholesterol to evaluate their effect on the liver and enteral cholesterol metabolism respectively. Results - The hydrolysates from the protein isolates showed similar. At higher doses of protein (above 70 mg/mL), the inhibition was stable at around 75 per cent. Regarding the hydrolyzate of bean flour extruded as it increases the amount of protein inhibitory capacity decreases. The hydrolysates were able to inhibit the micellar solubilization of cholesterol between 5 and 39 per cent. The thermal processing was the determining factor to decrease the solubility of cholesterol in vitro. Conclusion The hydrolysates of cowpea are able to inhibit the enzyme HMGR micellar solubilization and reducing cholesterol in vitro, even after being thermally processed beans. The ability of hydrolysates insolubilize cholesterol was improved by cooking in an autoclave and by extrusion

Apomixis is a clonal propagation method that produces offspring identical to the mother plant. With this feature, superior traits could be maintained over generations. However, our knowledge about apomixis is limited. In this study, we analyzed several apomictic Boechera embryologically to learn the details of apomixis. Meanwhile, we designed chemical treatments to successfully induce sex in apomictic plants and apomixis in sexual plants. Our experiments suggest that sex and apomixis coexist in plants and that sexual and apomictic reproduction are switchable by treating with specific chemicals.

Thesis (M.Sc) (Agriculture)--University of Limpopo, 2007. / Cowpea (Vigna unguiculata L. Walp) is one of the important food legumes and a valuable component of the traditional cropping systems. It serves as a source of protein in human diet and plays a major role in animal nutrition. The crop is adaptable to harsh environments including extreme temperatures and water limiting conditions. There is limited information available in cowpea with regards to cultivar selection and performance studies across ranges of environments in South Africa. The objectives of the present study were to 1) determine the influence of different planting dates and locations on phenology, yield and yield components of selected cowpea varieties and 2) determine the relationship of seed yield to environmental conditions such as rainfall and temperature. Ten cowpea genotypes were used for the study, developed by the Agricultural Research Council, Grain Crops Institute, South Africa. The experiment was laid out in a randomized complete block design with three replications. The experiment was carried out at Potchefstroom, Taung (Northwest Province) and Syferkuil (Limpopo Province) during three planting dates viz. 8 Nov. 22 Nov and 6 Dec. 2004. Data collected included the number of days to 50% flowering, number of days to 50% physiological maturity, seed yield, number of branches per plant, number of pods per plant, number of seeds per pod and 100 seed weight. The results showed highly significant differences among cowpea genotypes in each location and across locations for yield and yield components. Planting date one (i.e. 08 November) was better in yield gain over all locations. Potchefstroom was the best location for best yield gain due to high rainfall and relatively favorable low temperatures. The lowest yield was recorded at Syferkuil because of low rainfall and high temperatures. With relatively better performance across locations IT18E-16, CH14 and Pan311 were the best genotypes recommended in these or other similar environments in South Africa. / National Research Foundation (NRF)and Agricultural Research Council (ARC)

Thesis (MTech. degree in Agriculture.)--Tshwane University of Technology, 2011. / A ten week feeding trial was done with layer hens from 18 weeks of age to investigate whether cowpeas can be used as a single protein source for egg production.

This research study was designed to develop new food product formulations from whole cowpeas (Vigna sinensis) with high protein content and specific nutritional characteristics adequate to meet the requirements of both malnourished and well-nourished children. Highly acceptable food products were developed from either spray-dried or dry-roasted flours. These included a chocolate-flavored pudding, cowpea "butter," cookies, frozen desserts and all-purpose, whole wheat/cowpea breads. A rat feeding experiment to evaluate the nutritional qualities of the flours was carried out using Protein Efficiency Ratio (PER) as the evaluated parameter. Weanling male rats were fed diets with 10% protein (unsupplemented and supplemented) from cowpeas or casein (control). Methionine (0.36%), threonine (0.06%) and lysine (0.1%) were the supplementing amino acids used. Unsupplemented diets had very low PERs. The spray-dried flour diet supplemented with methionine had a PER about 15% greater than that of the control. The dry-roasted diet supplemented with methionine, threonine and lysine had a PER approximately equal to the control. It is concluded that it is possible to avoid or alleviate child protein malnutrition with either industrially- or home-produced food products formulated from whole cowpeas.

Thesis (M. S.)--Michigan State University. Dept. of Food Science and Human Nutrition, 2006. / Title from PDF t.p. (viewed on June 19, 2009) Includes bibliographical references (p. 67-70). Also issued in print.

Thesis (M.S.)--Michigan State University. Dept. of Agricultural, Food, and Resource Economics, 2008. / Title from PDF t.p. (viewed on Aug. 4, 2009) Includes bibliographical references (p. 317-321). Also issued in print.

Thesis (M.Sc.(Agric.))(Food Science)--University of Pretoria, 2006. / Includes summary. Includes bibliographical references. Available on the Internet via the World Wide Web.

Introdução - Devido ao perfil de mortalidade e de danos patológicos associados, as doenças cardiovasculares são consideradas um sério problema de saúde pública. Níveis de colesterol plasmático elevados fazem parte dos fatores de risco mais importantes para o desenvolvimento dessas doenças. Pesquisas recentes demostraram que a proteína do feijão caupi promove a redução dos níveis de colesterol em hamsters e em seres humanos, possivelmente pela ação de peptídeos bioativos advindos da dieta. Entretanto, a via pela qual o colesterol é inibido por esses peptídeos, assim como os efeitos do processamento na ação biológica ainda são desconhecidos. Objetivo - Verificar a via de ação hipocolesterolêmica dos hidrolisados do feijão caupi e o efeito do processamento térmico nesta propriedade. Métodos - Parte da farinha integral foi submetida ao isolamento de proteína e o restante dos grãos foi submetido à cocção em autoclave e à extrusão. Após ser cozido em autoclave, o feijão cozido também teve sua proteína isolada. Posteriormente, a proteína isolada do feijão integral e do feijão cozido foi submetida à hidrólise in vitro. O processo de extrusão foi modelado em função da expansão dos extrusados segundo a metodologia de superfície de resposta. A farinha do feijão extrusado foi submetida à hidrólise enzimática in vitro sem isolamento prévio da proteína. Os três hidrolisados foram submetidos à ultrafiltração e a fração menor que 3 kDa foi utilizada nos ensaios de inibição da enzima 3-hidroxi-3-metilglutaril coenzima A redutase (HMGR) e no ensaio de inibição da solubilização micelar do colesterol para avaliar a ação dos hidrolisados na via hepática e na via entérica do metabolismo do colesterol respectivamente. Resultados - Os hidrolisados provenientes dos isolados proteicos apresentaram comportamentos semelhantes. Em doses mais elevadas de proteína (acima de 70 µg/mL), a inibição apresentou-se estável, por volta dos 75 por cento. Em relação ao hidrolisado da farinha de feijão extrusado, à medida que se aumenta a quantidade de proteína a capacidade inibitória diminui. Os hidrolisados foram capazes de inibir a solubilização micelar do colesterol de 5 a 39 por cento. O processamento térmico foi fator determinante para diminuir a solubilização do colesterol in vitro. Conclusão Os hidrolisados do feijão caupi são capazes de inibir a enzima HMGR e reduzir a solubilização micelar do colesterol in vitro, mesmo após o feijão ser processado termicamente. A capacidade dos hidrolisados de insolubilizar o colesterol foi melhorada pelo cozimento em autoclave e pela extrusão / Introduction- The cardiovascular diseases, due to mortality and associated pathological damage, are considered a serious public health problem. Elevated plasma cholesterol levels are part of the most important risk factors for the development of these diseases. Recent research indicated that Cowpea protein promotes the reduction of cholesterol levels in hamsters and humans, possibly by the action of bioactive peptides from the diet. However, the route by which cholesterol is inhibited by peptides, as well as the processing effects on biological action are still unknown. Objective - To verify the hypocholesterolemic pathway of hydrolyzed cowpea and the effect of thermal processing on this property. Methods - Part of wholemeal flour was subjected to isolation of protein, and the remaining of the grains was subjected to retort and extrusion cooking processes. After autoclaving the grain, protein was also isolated from the flour. Subsequently, the isolated protein from wholemeal and cooked flour was subjected to in vitro hydrolysis. The extrusion process was optimized according to response surface methodology using the expansion ratio of extrudates as the dependent variable. The extruded bean flour was subjected to in vitro enzymatic hydrolysis without the isolation of the protein. The three hydrolysates were subjected to ultrafiltration and and fractions smaller than 3 kDa was used for inhibition assays of the enzyme 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) and for inhibition assay of micellar solubilization of cholesterol to evaluate their effect on the liver and enteral cholesterol metabolism respectively. Results - The hydrolysates from the protein isolates showed similar. At higher doses of protein (above 70 mg/mL), the inhibition was stable at around 75 per cent. Regarding the hydrolyzate of bean flour extruded as it increases the amount of protein inhibitory capacity decreases. The hydrolysates were able to inhibit the micellar solubilization of cholesterol between 5 and 39 per cent. The thermal processing was the determining factor to decrease the solubility of cholesterol in vitro. Conclusion The hydrolysates of cowpea are able to inhibit the enzyme HMGR micellar solubilization and reducing cholesterol in vitro, even after being thermally processed beans. The ability of hydrolysates insolubilize cholesterol was improved by cooking in an autoclave and by extrusion