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.

This book focuses on food security and safety issues in Africa, a continent presently challenged with malnutrition and food insecurity. The continuous increase in the human population of Africa will lead to higher food demands, and climate change has already affected food production in most parts of Africa, resulting in drought, reduced crop yields, and loss of livestock and income. For Africa to be food-secure, safe and nutritious food has to be available, well-distributed, and sufficient to meet people’s food requirements. Contributors to Food Security and Safety: African Perspectives offer solutions to the lack of adequate safe and nutritious food in sub-Saharan Africa, as well as highlight the positive efforts being made to address this lack through a holistic approach. The book discusses the various methods used to enhance food security, such as food fortification, fermentation, genetic modification, and plant breeding for improved yield and resistance to diseases. Authors emphasize the importance of hygiene and food safety in food preparation and preservation, and address how the constraints of climate change could be overcome using smart crops. As a comprehensive reference text, Food Security and Safety: African Perspectives seeks to address challenges specific to the African continent while enhancing the global knowledge base around food security, food safety, and food production in an era of rapid climate change.

This book is a printed edition of the Special Issue "Forage Plant Ecophysiology" that was published in Agriculture

In the context of improving water productivity, there is a growing interest in deficit irrigation, an irrigation practice whereby water supply is reduced below maximum levels and mild stress is allowed with minimal effects on yield. Under conditions of scarce water supply and drought, deficit irrigation can lead to greater economic gains than maximizing yields per unit of water for a given crop; farmers are more inclined to use water more efficiently, and more water-efficient cash crop selection helps optimize returns. However, this approach requires precise knowledge of crop response to water as drought tolerance varies considerably by species, cultivar and stage of growth. The studies present the latest research concepts and involve various practices for deficit irrigation. Both annual and perennial crops were exposed to different levels of water stress, either during a particular growth phase, throughout the whole growing season or in a combination of growth stages. The overall finding, based on the synthesis of the different contributions, is that deficit or regulated-deficit irrigation can be beneficial where appropriately applied. Substantial savings of water can be achieved with little impact on the quality and quantity of the harvested yield. However, to be successful, an intimate knowledge of crop behavior is required, as crop response to water stress varies considerably.

Breeding Oilseed Crops for Sustainable Production: Opportunities and Constraints presents key insights into accelerating the breeding of sustainable and superior varieties. The book explores the genetic engineering/biotechnology that has played a vital role in transforming economically important traits from distant/wild species to cultivated varieties, enhancing the quality and quantity of oil and seed yield production. Integrated nutrient management, efficient water management, and forecasting models for pests diseases outbreaks and integrated pest and pest management have also added new dimensions in breeding for sustainable production. With the rise in demand, the scientific community has responded positively by directing a greater amount of research towards sustainable production both for edible and industrial uses. Covering the latest information on various major world oil crops including rapeseed mustard, sunflower, groundnut, sesame, oilpalm, cotton, linseed/flax, castor and olive, this book brings the latest advances together in a single volume for researchers and advanced level students. - Describes various methods and systems to achieve sustainable production in all major oilseed crops - Addresses breeding, biology and utilization aspects simultaneously including those species whose information is not available elsewhere - Includes information on modern biotechnological and molecular techniques and production technologies - Relevant for international government, industrial and academic programs in research and development

This topic is a unique attempt to simultaneously tackle theoretical and practical aspects in drought phenotyping, through both crop-specific and cross-cutting approaches. It is designed for – and will be of use to – practitioners and postgraduate students in plant science, who are grappling with the challenging task of evaluating germplasm performance under different water regimes. In Part I, different methodologies are presented for accurately characterising environmental conditions, implementing trials, and capturing and analysing the information this generates, regardless of the crop. Part II presents the state-of-art in research on adaptation to drought, and recommends specific protocols to measure different traits in major food crops (focusing on particular cereals, legumes and clonal crops). The topic is part of the CGIAR Generation Challenge Programme’s efforts to disseminate crop research information, tools and protocols, for improving characterisation of environments and phenotyping conditions. The goal is to enhance expertise in testing locations, and to stimulate the development and use of traits related to drought tolerance, as well as innovative protocols for crop characterisation and breeding.