Download or read book Evaluating the Impacts of Waterlogging Stress on Cowpea Vigna Unguiculata L Growth Traits and Physiological Performance written by Omolayo Joshua Olorunwa and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The progressive increase in the global population and the rapidly changing climate have put unprecedented pressure on crop production. Cowpea is one of the world’s most important leguminous crops, contributing to food security and environmental sustainability. However, cowpea productivity is limited due to waterlogging stress. The main objective of this study was to explore physiological and biochemical mechanisms to understand how cowpea genotypes respond to waterlogging stress. Four studies were conducted in controlled and field conditions to achieve these objectives. Study 1 characterized the waterlogging tolerance of 30 cowpea genotypes in a controlled environment using 24 morphophysiological parameters with waterlogging tolerance coefficients and multivariate analysis methods. 10% of the genotypes exhibited high tolerance to waterlogging stress, and the genotypes UCR 369 and EpicSelect.4 were identified as the most and least waterlogging tolerant, respectively. Study 2 evaluated the key parameters influencing carbon fixation of UCR 369 and EpicSelect.4 at the reproductive stage. The less tolerant EpicSelect.4 experienced high downregulation of stomatal and non-stomatal limiting factors during waterlogging and recovery, resulting in decreased carbon assimilation rates. UCR 369 rapidly developed adventitious roots, maintained biomass, and restored pigments and metabolites to sustain photosynthesis. A two-year field experiment was conducted in study 3 to quantify the effects of waterlogging on the yields, physiology, and biochemistry of cowpeas at different growth stages. The most apparent impact of waterlogging stress occurred at the reproductive stage, followed by the vegetative and maturity growth stages. Studies suggest that diverse cowpea genotypes have distinct physiological and biochemical mechanisms in response to waterlogging stress. In addition, the tolerant genotypes and traits identified herein can be used in genetic engineering and cowpea breeding programs that integrate increased yield with waterlogging stress tolerance.

Download or read book Evaluation of Physiological Parameters and Nitrogen Partitioning and Remobilization in Beans Phaseolus Vulgaris L and Cowpeas Vigna Unguiculata walp L Under Stress and Non stress Soil Moisture Conditions written by Mmasera Manthe and published by . This book was released on 1994 with total page 460 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Gas exchange evapotranspiration efficiency morphophysiology and productivity of cowpeas under water deficit written by Samson Huni and published by Cuvillier Verlag. This book was released on 2010-12-23 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt: The cowpea [Vigna unguiculata (L.) Walp.], a legume which originated in Africa, is now grown in the Tropics and many subtropical regions. Cowpea is of significance for food and feed and its yield is frequently severely affected by drought, resulting in its low average yield. Hence the influence of water deficit on gas exchange, growth, development and yield of cowpea was studied here, with the aim of contributing to our understanding of the response of cowpeas to water deficit and to the provision of efficient and viable information for breeding of drought resistant genotypes. To achieve this aim, several traits were examined, which included - gas exchange [stomatal conductance (gs), net photosynthetic rate PN), transpiration rate (E) and intrinsic transpiration efficiency TEi)], evapotranspiration efficiency (ETE), water use (WU) and yield/yield components, - relationship among these traits and variability among the various genotypes. From the results it was expected that it would be possible to find efficient plant types and characteristics to predict ETE and yield which could eventually be used in cowpea drought resistance breeding programmes. For this purpose three pot experiments were conducted in the greenhouse under drip irrigation. The control (well-watered treatment) was irrigated continuously from the beginning to the end of the experiments, while the water-deficit treatment experienced a reduced irrigation resulting in a soil water potential of -350 to -450hPa at the onset of flowering for 14 to 21 days. Measurement and analyses of various traits were carried out before the induction of water-deficit stress, during and at the end of stress. All remaining plants were then fully irrigated up to the end of the experiments. In experiments 1 and 2 the plants were harvested at maturity to determine yield and yield components, and biomass and ETE. Water-deficit stress impacted on all analysed traits and there were variations among genotypes in both treatments. Water deficit elicited the reduction of leaf relative water content and stomatal conductance. Consequently, PN and E declined as well. However, E decreased more than PN due to the influence of stress, generally leading to a higher TEi of the water-deficit treatment. There were differences among experiments, probably due to interactions between the genotypes and the environment. After stress, gas exchange recovered to similar levels of the control treatment. Biomass production, water use and evapotranspiration efficiency varied among genotypes within and between treatments. Compared with the control, water use and growth rate decreased clearly under stress. The role of PN for biomass production became evident in the positive correlation between both parameters. TEi had no distinct relationship to ETE. Three traits, specifically leaf temperature (ΔT), leaf senescence (expressed as leaf shedding score, LSS) and cell membrane stability (CMS, calculated from electrolyte leakage values) distinguish themselves as valuable tools for drought resistance analysis. ΔT rose up to 3°C higher under stress than well-watered conditions. LSS increased under stress as well, whereby the genotypes which shed a relative high number of leaves under well-watered conditions also shed an even higher amount of leaves under stress. The sole genotype which retained all its leaves under stress, UCR 328, maintained all its leaves green, which was probably tremendously valuable for a quick recovery of different plant processes after stress. ΔT was consistently positively correlated with LSS, but negatively with CMS, particularly under stress. ΔT and LSS also displayed significant relationships with ETE, TEi, grain yield and harvest index (HI). Owing to the fact that ΔT and LSS are simple, fast, cheap and non-invasively determined, they could be used in drought resistance breeding programmes as indirect selection traits for efficient plant types regarding transpiration, TEi, ETE and yield. The various genotypes yielded differently and the HI also varied under both treatments, a probable indication of differing genotypic yield potential. Water deficit at flowering reduced yield, but some genotypes had a higher HI. Generally, the genotypes with a high “yield potential” also manifested a higher yield under stress. TVu 12348 had the highest yield stability, but a low yield potential. UCR 328 and IFH 27-8 had a relatively high yield stability coupled with a high yield under stress.

Download or read book Growth and Yield Responses of Cowpeas Vigna Unguiculata L to Water Stress and Defoliation written by Zinhle Ntombela and published by . This book was released on 2012 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Morphological and Physiological Responses of Cowpea Vigna Unguiculata L Walp Cultivars to Induced Water Stress and Phosphorus Nutrition written by Rogério Marcos Chiulele and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Soil Water Deficit and Physiological Issues in Plants written by Amitav Bhattacharya and published by Springer Nature. This book was released on 2021-02-25 with total page 717 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book explores the impact of soil water deficiency on various aspects of physiological processes in plants. The book explains the effects under soil water deficit condition such as lowering of plant water content, disturbance in carbon metabolism such in photosynthesis, photorespiration and respiration as well as effects of soil water deficit on nitrogen metabolism. The book also educates the readers about, mineral nutrition under soil water deficit condition and roles of different nutrient to overcome water deficit. Changes in growth and development pattern of plant under soil water deficit condition and effects on growth and development are elaborated. This book is of interest to teachers, researchers, scientists in botany and agriculture. Also the book serves as additional reading material for undergraduate and graduate students of agriculture, forestry, ecology, soil science, and environmental sciences. National and international agricultural scientists, policy makers will also find this to be a useful read. The in depth description of the major physiological issues in plants under soil water deficit that are presented in this book will help breeders tailoring crops for desirable physiological survival traits in the face of increasing soil water deficit. This book is an impactful addition to the library of any faculty members, researchers, agricultural policy planner, post graduate or student studying in plant physiology, biochemistry, microbiology and other subjects related to crop husbandry.

Download or read book Developing Screening Tools for Abiotic Stresses Using Cowpea Vigna Unguiculata L Walp as a Model Crop written by Shardendu Kumar Singh and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abiotic stresses cause extensive loss to agriculture production worldwide. Cowpea is an important legume crop grown widely in tropical and subtropical regions where high temperature, ultraviolet-B (UVB) radiation and drought are the common stress factors limiting production. Various vegetative, physiological, biochemical and reproductive plant attributes were assessed under a range of UVB radiation levels in Experiment I and in a combination with two doses of each carbon dioxide concentration [CO2], temperature, and UVB radiation and their interactions in Experiment II by using six cowpea genotypes and sunlit plant growth chambers. The dynamics of photosynthesis and fluorescence processes were assessed in 15 cowpea genotypes under drought condition in Experiment III in pot-grown plants under sunlit conditions. A distinct response pattern was not observed in cowpea in response to UVB radiation from 0 to 15 kJ; however, plants grown under elevated UVB showed reduced photosynthesis resulting in shorter plants and produced smaller flowers and lower seed yield. Increased phenolic compounds appeared to be a defense response to UVB radiation. The growth enhancements observed by doubling of [CO2] were not observed when plants were grown in combination with elevated UVB or temperature which also showed the most detrimental effects on plant growth and seed yield. Results from Experiment I and II revealed that cowpea reproductive traits were highly sensitive to abiotic stresses compared to the vegetative growth and development. A total stress response index (TSRI) technique, derived from all vegetative and reproductive parameters, was used to screen genotypes for their stress tolerance to UVB or combination of stresses. An increase in water use efficiency while maintaining higher rate of photosynthesis was an important drought tolerance mechanism in tolerant cowpea genotypes. Using principal component analysis technique, four groups of the genotypes were identified for their drought tolerance. Evaluating same genotypes across stress conditions revealed that no single genotype has the absolute tolerance characters to all stress conditions. The identified diversity for abiotic stress tolerance among cowpea genotypes and associated traits can be used to develop tolerant genotypes suitable for an agro-ecological niche though traditional breeding or genetic engineering methods.

Download or read book Assessing successive leaf yield performance of dual purpose cowpea Vigna unguiculata to decrease seasonal shortage of nutrients in resource poor small scale households of Tanzania and Uganda written by Severin Polreich and published by Cuvillier Verlag. This book was released on 2011-03-23 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study presents a method to assess yield performance of dual-purpose cowpea types for human consumption and to reveal potentials for further improvement of its use as leafy vegetable. Eleven cowpea accessions with different genetic background and sample status were chosen from AVRDC’s working collection in Arusha, Tanzania. Among them, dual-purpose cowpeas like Dakawa, Ex Iseke and Ngoji were present that the center has been distributing to local farmers. Multi-location trials in typical cowpea production environments were established both on farm and on station in the regions Arusha, Dodoma, and Kilimanjaro in Tanzania and in Eastern Region, Uganda during the short and long rainy season 2007 and 2008, respectively. Young, tender leaves were picked in successive leaf harvests about every and two weeks until the plants did not produce further leaves. Cowpea seeds were harvested when pods reached 80% maturity. Data of yield parameters were analyzed with analysis of variance (ANOVA), stability analyses were carried out according to the dynamic and static concepts. Reliability of leaf and seed yield performances were calculated based on the probability of outperformance of local check cowpeas that were previously recommended by farmers and extension workers in informal group sessions. Through NIRS, crude protein and iron contents were assessed in leaves obtained from the second leaf harvests at the different locations and from up to subsequent leaf harvests. Dual-purpose utility for smallholders was assessed through (i) an index of superiority (Si), in which reliabilities of leaf yield across repeated leaf harvests and seed yield were weighed and combined to overall yield benefit of the ith accession, (ii) effective plot length for nutritional component XY, to calculate the length of a plot (in m) that needs to be planted to sustain a five-head household for ten days with a recommended amount of nutrients, and (iii) responsiveness (Resp), reflecting changes of leaf yield (compensation) relative to changes in seed yield (sensitiveness) if harvesting frequency was intensified. Performance of single leaf yields was strongly influenced by environmental factors and, only in Arusha, accession-specific. Interactions between yield reliability and stability were site-specific. Overall, test-accessions achieved higher reliabilities in seed yield than in leaf yield. Only in the on-station trial in Eastern Region, accession IT82D-889, and in the on-farm trial in Kilimanjaro, ILRI11114 and Ex Iseke showed leaf yield reliabilities above 0.50. Iron content in cowpea leaves was highly dependent on environmental influences and varied from 157.4 mg kg-1 to 286.1 mg kg-1. Leaf CP had a broad-sense heritability of 0.87. Across accessions and environments the mean leaf CP content ranged from 37.4% of DM (IT93K-2045-29) to 33.9% of DM (Sudan). CP and leaf dry matter (DM) yield had significantly negative correlation coefficients between. Means of effective plot length for crude protein and iron varied by more than 50% across environments. Although CP, in contrast to iron, was genetically determined, its impact on differences in effective plot length was negligible as well, as differences in production of leaf DM per m2 were by far larger among accessions than those of CP contents. It was recommended to favor accessions with short effective plot lengths and higher CP contents in leaf yields over those with short effective plot lengths and low CP contents. In contrast to determinate cowpeas, indeterminate types increased their DM gain in aerial plant parts of leaf-harvested plants relatively to unharvested plants. Indeterminate cowpeas responded with high leaf yield increases if leaves were picked twice a week. Consequently yields of total edible DM of these plant types, comprising added seed and leaf yields, increased with intensification of leaf-harvesting frequency from once to twice a week. Determinate plant types yielded highest in total edible DM when only seed was harvested or in less intensive leaf-harvesting scenarios. Accessions with favorable responsiveness, reflecting leaf yield changes relative to seed yield changes under intensified leaf-harvesting frequency, were Sudan, ILRI11114, and IT93K2045-29. In contrast, Resps of SAM45 and ILRI15742 were poorest. Traits have to be identified that could explicitly improve Resp of cowpea types. Improving quantitative yield parameters should not result in quality decrease. The dual-purpose characteristics of local checks were mainly superior to the eleven test-accessions pointing to a demand on improved leaf yield performance that is not merely total leaf yield amount but also the continuance during repeated leaf harvesting. By the proposed method the status quo of a defined location, i.e. site-specific demands on germplasm, can be included in the analysis, serving as benchmark for improvement if the local check is chosen carefully. Since single leaf yields are the results of fairly complex and dynamic interactions between plant physiological processes and environmental conditions it is essential to conduct participatory variety selection and plant breeding trials for dual-purpose assessments in target environments and not ex situ.

Download or read book Physiological Responses of Cowpea Vigna Unguiculata to Water Stress Under Varying Water Regimes written by Kalanda Ilunga and published by . This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effects of Glycine Betaine on Plant Growth and Performance of Alfalfa Medicago Sativa L Cowpea Vigna Unguiculata L Walp Within Water Deficit Conditions written by Hanan Kamal Khadouri and published by . This book was released on 2015 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt: Managing water consumption of the crops is one of the strategies which have been adopted locally and worldwide in current trends of sustainable agriculture, in addition to the low level of water resources in UAE because of the rare precipitation, no fresh free flowing water; no rivers, lakes or streams. The present study was objective to evaluate the effects of organic exogenous Glycine Betaine on two forage crops Alfa alfa (Medicago sativa L.) & Cowpea (Vigna unguiculata L. Walp.) within different levels of drought stress. A pot experiment was designed on completely randomized block design (CRBD) with three replicates in each treatment in each plant. Seeds were germinated and the plants watered as required. Exogenous Glycine Betaine was applied as foliar spray in three concentrations (0,100 and 200 ppm) for five times with five days intervals. Water deficit stress start within the second Glycine Betaine treatment in three levels (24h: 100% well-watered recommended), (48h: 60% water deficit) and (72h: 40% water deficit) depending on the required quantity. Growth characteristics, pigment concentrations, biochemical content and Mineral nutrients levels were measured in response to the treatment variables. Results show Glycine Betaine has significant increment in Growth parameters, biochemical contents and Mineral nutrients concentrations. As a conclusion the results suggest that exogenous applications of Glycine Betaine were improve the drought tolerance in Cowpea and has enhanced the Alfa alfa performance under water deficit stress in both concentrations 100 & 200 ppm under drought stress of 60% of irrigations water . In due of comparison of Cowpea and Alfa alfa in their response to Glycine Betaine under the water deficit conditions, it's found from this study that Glycine Betaine has better effect on the Cowpea under drought stress than Alfa alfa.

Download or read book Dry matter partitioning of bean Phaseolus vulgaris L and cowpea Vigna unguiculata L Walp under water deficit conditions written by M. T. de CASTRO NETO and published by . This book was released on 1991 with total page 171 pages. Available in PDF, EPUB and Kindle. Book excerpt: Introduction; Literature review; Taxonomy of the grain legumes; Biological structure and growth habit; Photosynthesis and sink demand; Phloem loading; Interorgan transport; Phloem Unloading; Water stress and Photosynthesis; Rate and duration of seed filling; Water stress effects on the translocation of assimilates; Growth and physiology of stressed tissues; Turgor maintenance; Materials and methods; Field studies; Glasshouse studies; Influence of water stress on yield and yield components of cowpea and beans grown under field and glasshouse conditions; Plant and fruit water status; Photosynthesis and water stress; Water stress and translocation; Partitioning of dry matter; Leaf area index (LAI) and net assimilation rate (NAR); Pod and seed growth rate and duration; Anatomical study of vascular system of the funiculus and seed coat of beans plants.

Download or read book Relationship Between Seed Density and Quality of Cowpea Vigna Unguiculata L Walp Seeds written by E. H. N. Vieira and published by . This book was released on 1991 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt: Field and laboratory experiments were conducted to evaluate the effects of seed specific gravity, and/or seed density, on physiological quality, storability and seedling performance of cowpea (Vigna unguiculata (L.) Walp) seeds. Seed preparation was accomplished by two methods: using aqueous sucrose solutions and by means of a table model fractionating aspirator.

Download or read book Evaluation of Diverse Cowpea Vigna Unguiculata L Walp Germplasm for Field Performance and Drought Tolerance written by K. D Nkoana and published by . This book was released on 2018 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Reproductive Physiology of Cowpea Vigna Unguiculata L Walp at High Temperatures with Different Photoperiods written by Randall Gordon Mutters and published by . This book was released on 1988 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Physiology and Genetics of Drought Tolerance in Cowpea and Winter Wheat written by David Adrian Verbree and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In the wake of rising temperatures, erratic rainfall, and declining ground water table, breeding for drought tolerance in food crops has become a top priority throughout the world. Phenotyping a large population of breeding lines for drought tolerance is time-consuming and often unreliable due to multiple possible mechanisms involved. In cowpea (Vigna unguiculata L. Walp), a box-screening method has been used to partition the confounding effects that shoot and root traits have on drought tolerance by restricting root growth and providing a homogeneous soil moisture environment across genotypes. Nonetheless, multiple mechanisms of shoot drought tolerance have been reported which further complicate phenotyping. In winter wheat (Triticum aestivum L.), canopy temperature depression (CTD) has been proposed as a good indicator of drought tolerance. The recent development of low-cost thermal imaging devices could enable high-throughput phenotyping of canopy temperature. While CTD can be an indicator of overall plant water status, it can be confounded by high stomatal resistance, which is another seemingly contradictory mechanism of drought tolerance. The objectives of this study were to explore the physiological basis and genetics of the two mechanisms of shoot drought tolerance previously reported in cowpea and to develop and evaluate a method of high-throughput phenotyping of drought tolerance in winter wheat using thermal imaging. In cowpea, a legume well known for its tight stomatal control, no differences in gas exchange between drought tolerant and susceptible genotypes were observed. A unifoliate stay-green trait was discovered that segregates as a single recessive gene. However, it did not correlate with trifoliate necrosis or overall drought tolerance. In winter wheat, CTD did not always correlate with yield under rainfed conditions. One drought-tolerant cultivar, in particular, had the hottest canopy temperature, possibly because it was able to conserve moisture by closing its stomata whereas another closely related drought-tolerant cultivar had the coolest canopy temperature. Therefore, it appears that no single method of phenotyping for drought tolerance can be broadly applied across all genotypes of a given species due to possible contrasting mechanisms of drought-tolerance and environmental differences. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/152439

Download or read book The Physiological and Molecular Effects of Fumonism B1 on Cowpea Vigna Unguiculata L Walp written by Richard Gavin Kotze and published by . This book was released on 2015 with total page 220 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cowpea (Vigna unguiculata) is an edible annual leguminous crop cultivated by many subsistence and rural communities in developing countries in subtropical areas of the world. Cowpea is a very versatile, well adapted and nutritious grain legume. However, cowpea seed is prone to fungal infestation under suboptimal storage conditions. Some of these fungi, including Aspergillus and Fusarium spp., produce their associated mycotoxins under these conditions. Fumonisins are produced primarily by Fusarium verticillioides and F. proliferatum and are known to be toxic to vertebrates and plants. Fumonisin B1 is phytotoxic to cowpea seeds and is speculated to inhibit ceramide synthase in the sphingolipid pathway in plants. This study was done to determine the phytotoxic effects of FB1 on cowpea seedlings and to provide insight on the mode of action of the toxin at a molecular level. Surface-disinfected seeds were imbibed for 10 h in sterile distilled water amended with FB1 to yield final concentrations of 2, 20 and 40 mg/L. Slow imbibed seeds (placed in moist paper towels) and seeds placed in sterile distilled water for 10 h served as the positive and negative controls, respectively. Additionally cowpea seeds were inoculated with the conidia of three different FB1-producing Fusarium verticillioides strains. Percentage emergence was determined after seven dpi whereas, seedling mass, length and seedling vigour index where determined after seven and 21 dpi. Total chlorophyll content was measured after 14 and 21 dpi. Stunted growth was observed in FB1 treated seedlings. Emergence was reduced by all three FB1 concentrations as well as in seeds treated with F. verticillioides strain MRC 8265. Seedlings imbibed in 40 mg/L FB1 had reduced seedling length. Seedling mass was reduced by all three FB1 concentrations as well as all three Fusarium strains. Total chlorophyll content was higher for seeds imbibed in all three FB1 concentrations when compared to both controls. This is in contrast to other studies which reported that FB1 causes chlorosis in plants. In order to evaluate the effect of FB1 on ceramide synthase gene expression seeds were imbibed in a 20 mg/L FB1 solution and the control seeds were imbibed in sterile distilled water. RNA was extracted from untreated and treated samples after 0, 3 and 12 dpi with the latter being divided into shoot and roots samples. cDNA was synthesised from the extracted RNA samples. Amplification of the ceramide synthase gene was done using primers that were designed to the conserved regions of Glycine max and Phaseolus vulgaris ceramide synthase gene homologues. Sequence analysis revealed that the designed primers did amplify the correct gene from cowpea seedlings. The expression levels of the ceramide synthase gene from cowpea were thus tested using semi-quantitative PCR amplification. No significant differences in ceramide synthase gene expression were observed between the control and toxin treated samples. Two FB1 unrelated differences were observed. A possible developmental difference was observed as ceramide synthase gene expression decreased over time in both the control and treated samples. It thus seems that FB1 did not influence ceramide synthase gene expression in cowpea.

Download or read book DEVELOPING SCREENING TOOLS FOR ABIOTIC STRESSES USING COWPEA VIGNA UNGUICULATA L WALP AS A MODEL CROP written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abiotic stresses cause extensive loss to agriculture production worldwide. Cowpea is an important legume crop grown widely in tropical and subtropical regions where high temperature, ultraviolet-B (UVB) radiation and drought are the common stress factors limiting production. Various vegetative, physiological, biochemical and reproductive plant attributes were assessed under a range of UVB radiation levels in Experiment I and in a combination with two doses of each carbon dioxide concentration [CO2], temperature, and UVB radiation and their interactions in Experiment II by using six cowpea genotypes and sunlit plant growth chambers. The dynamics of photosynthesis and fluorescence processes were assessed in 15 cowpea genotypes under drought condition in Experiment III in pot-grown plants under sunlit conditions. A distinct response pattern was not observed in cowpea in response to UVB radiation form 0 to 15 kJ; however, plants grown under elevated UVB showed reduced photosynthesis resulting in shorter plants and produced smaller flowers and lower seed yield. Increased phenolic compounds appeared to be a defense response to UVB radiation. The growth enhancements observed by doubling of [CO2] were not observed when plants were grown in combination with elevated UVB or temperature which also showed the most detrimental effects on plant growth and seed yield. Results form Experiment I and II revealed that cowpea reproductive traits were highly sensitive to abiotic stresses compared to the vegetative growth and development. A total stress response index (TSRI) technique, derived from all vegetative and reproductive parameters, was used to screen genotypes for their stress tolerance to UVB or combination of stresses. An increase in water use efficiency while maintaining higher rate of photosynthesis was an important drought tolerance mechanism in tolerant cowpea genotypes. Using principal component analysis technique, four groups of the genotypes were.