Abiotic Stresses: Alteration of Composition and Grain Quality in Food Legumes

Abiotic stresses varyingly affect the grain composition and quality of food legumes. This paper is aimed at discussing the impact of abiotic stresses on the grain composition and quality of food legumes. As protein is the main grain constituent of food legumes for which it is being consumed by humans as a cheap protein source, abiotic stresses such as heat, cold, drought, salinity and heavy metals alter this grain protein content in different dimensions for different food legumes. Moreover, other valuable constituents such as starch, soluble sugar, oil, fatty acid and fiber content are affected differently by the abiotic stresses. The diverse impact of these abiotic stresses ultimately declines the grain quality and yield of food legumes. As food legumes play a vital role in the nutritional diet of millions of people in the world and are occasionally denoted as the meat of poor people, it is important to recognize that the sustainable production of food legumes, even under various environmental stresses, has the potential to ensure protein security for people globally. Therefore, it has become a necessity to improve the productivity and quality of food legumes under abiotic stresses through proper crop management and improved breeding strategies, thus enhancing food and economic security to the farmers, particularly in the developing countries of the world.

Characterization of Nutritional Quality Traits of a Common Bean Germplasm Collection

Food legumes are at the crossroads of many societal challenges that involve agriculture, such as climate change and food sustainability and security. In this context, pulses have a crucial role in the development of plant-based diets, as they represent a very good source of nutritional components and improve soil fertility, such as by nitrogen fixation through symbiosis with rhizobia. The main contribution to promotion of food legumes in agroecosystems will come from plant breeding, which is guaranteed by the availability of well-characterized genetic resources. Here, we analyze seeds of 25 American and European common bean purified accessions (i.e., lines of single seed descent) for different morphological and compositional quality traits. Significant differences among the accessions and superior genotypes for important nutritional traits are identified, with some lines showing extreme values for more than one trait. Heritability estimates indicate the importance of considering the effects of environmental growth conditions on seed compositional traits. They suggest the need for more phenotypic characterization in different environments over different years to better characterize combined effects of environment and genotype on nutritional trait variations. Finally, adaptation following the introduction and spread of common bean in Europe seems to have affected its nutritional profile. This finding further suggests the relevance of evolutionary studies to guide breeders in the choice of plant genetic resources.

Drought and Heat Stress in Cool-Season Food Legumes in Sub-Tropical Regions: Consequences, Adaptation, and Mitigation Strategies

Drought and heat stress are two major abiotic stresses that challenge the sustainability of agriculture to a larger extend. The changing and unpredictable climate further aggravates the efforts made by researchers as well as farmers. The stresses during the terminal stage of cool-season food legumes may affect numerous physiological and biochemical reactions that may result in poor yield. The plants possess a good number of adaptative and avoiding mechanisms to sustain the adverse situation. The various agronomic and breeding approaches may help in stress-induced alteration. The physiological and biochemical response of crops to any adverse situation is very important to understand to develop mechanisms and approaches for tolerance in plants. Agronomic approaches like altering the planting time, seed priming, foliar application of various macro and micro nutrients, and the application of rhizobacteria may help in mitigating the adverse effect of heat and drought stress to some extent. Breeding approaches like trait-based selection, inheritance studies of marker-based selection, genetic approaches using the transcriptome and metabolome may further pave the way to select and develop crops with better heat and drought stress adaptation and mitigation.

Factors affecting the commercialization of food legumes in North Cameroon

The study focused on factors affecting the commercialization of food legumes-cowpeas (Vigna unguiculata), bambara groundnuts(Vignasubterranea), groundnuts (Arachis hypogaea) and soybeans (Glycine max) in two departments (Benouéand Mayo-Louti) of the North Region of Cameroon. Qualitative and quantitative methods were used to collect data. Qualitative methods involved focus group discussions and direct observations. A structured interview guide was administered in major peri-urban and urban markets to get supportive quantitative data. The respondents were selected using purposive sampling technique. A content analysis was conducted and quantitative data was analyzed with the aid of XLSTAT 2007 software and Excel. A cross-section of the age and gender population was involved in the marketing of food legumes. Women constituted more than 80% in the retail sector on peri-urban markets. The study found that 100% of the vendors had never got any form of training on business management before engaging into the sector. Socio-cultural factors were determinant factors that impacted negatively in promoting an entrepreneurial culture among women. The marginalization of women, the restriction of land ownership by traditional tenure and poor distribution of land for agriculture were some of the main constraints faced by women. The impediments of women’s empowerment include their lack of access to the decision-making process, low participation in local governance and limited access to technology inputs and credit. Traditional practices forbid women and girls to have or manage large amounts of money. Such restrictions have serious consequences on agricultural production. Instead of exploiting the productive capacity of women at all levels, including food production and transformation, some of the traditions simply stifle their potential energies. In addition to socio-cultural factors, major bottlenecks faced in the production and commercialisation of food legumes includes social structural and institutional, agronomic, natural(biotic and abiotic stress)and climatic factors. Development of intervention strategies through exogenous innovation techniques might act as an incentive for smallholder farmers to invest more of their land and energy in cultivation of food legumes. More attention should be focused on market research and development with crop improvement programmes that are economically profitable, if food legumes are to continue making a greater contribution to the household income, nutrition and sustainable development in North Cameroon.

Current Perspectives on Introgression Breeding in Food Legumes

Food legumes are important for defeating malnutrition and sustaining agri-food systems globally. Breeding efforts in legume crops have been largely confined to the exploitation of genetic variation available within the primary genepool, resulting in narrow genetic base. Introgression as a breeding scheme has been remarkably successful for an array of inheritance and molecular studies in food legumes. Crop wild relatives (CWRs), landraces, and exotic germplasm offer great potential for introgression of novel variation not only to widen the genetic base of the elite genepool for continuous incremental gains over breeding cycles but also to discover the cryptic genetic variation hitherto unexpressed. CWRs also harbor positive quantitative trait loci (QTLs) for improving agronomic traits. However, for transferring polygenic traits, “specialized population concept” has been advocated for transferring QTLs from CWR into elite backgrounds. Recently, introgression breeding has been successful in developing improved cultivars in chickpea (Cicer arietinum), pigeonpea (Cajanus cajan), peanut (Arachis hypogaea), lentil (Lens culinaris), mungbean (Vigna radiata), urdbean (Vigna mungo), and common bean (Phaseolus vulgaris). Successful examples indicated that the usable genetic variation could be exploited by unleashing new gene recombination and hidden variability even in late filial generations. In mungbean alone, distant hybridization has been deployed to develop seven improved commercial cultivars, whereas in urdbean, three such cultivars have been reported. Similarly, in chickpea, three superior cultivars have been developed from crosses between C. arietinum and Cicer reticulatum. Pigeonpea has benefited the most where different cytoplasmic male sterility genes have been transferred from CWRs, whereas a number of disease-resistant germplasm have also been developed in Phaseolus. As vertical gene transfer has resulted in most of the useful gene introgressions of practical importance in food legumes, the horizontal gene transfer through transgenic technology, somatic hybridization, and, more recently, intragenesis also offer promise. The gains through introgression breeding are significant and underline the need of bringing it in the purview of mainstream breeding while deploying tools and techniques to increase the recombination rate in wide crosses and reduce the linkage drag. The resurgence of interest in introgression breeding needs to be capitalized for development of commercial food legume cultivars.

Emergence of Maruca vitrata as a Major Pest of Food Legumes and Evolution of Management Practices in Asia and Africa

Legume pod borer, Maruca vitrata, has emerged as a major pest on food legumes in Asia and Africa. It is an oligophagous pest, feeding on over 70 species in Fabaceae. We examine the species complex in Asia, Africa, Oceania, and the Americas, with an emphasis on molecular taxonomy. Studies on pheromone production and perception suggest the existence of pheromone polymorphism, especially in Asia and Africa. No Maruca-resistant varieties are available in the major food legumes including cowpea, pigeonpea, mungbean, and yard-long bean. Legume growers use chemical pesticides indiscriminately, leading to the development of pesticide resistance. However recent developments in habitat management, classical biocontrol with more efficient parasitoids, biopesticides, and judicious use of insecticides pave the way for sustainable management of M. vitrata, which can reduce the pesticide misuse. Active engagement of the private sector and policy makers can increase the adoption of integrated pest management approaches in food legumes.