Phaseolus Species Responses and Tolerance to Drought

Abstract

Drought is the main abiotic stress limiting bean crop yield in smallholder systems in developing countries. Phaseolus is one of the main genera among the cultivated grain legumes, with a wide range of adaptations to different environments, from humid tropics to deserts. Among the Phaseolus species, five are known to have been domesticated and cultivated; common bean (P. vulgaris) being the most economically important, while tepary bean (P. acutifolius) is better adapted to drought. Drought stress affects growth, development, and yield of beans. Terminal drought can be catastrophic for farmers’ crop yields. Several studies have been carried out to: Characterize the physiological responses to drought stress; identify developmental and physiological traits related to drought tolerance; and identify the possible genes involved. Crop responses to drought are very varied, depending on the species and cultivar; reflecting their unique environmental, evolutionary, and/or domestication history. Potential target traits include water use efficiency, effective use of water, rooting depth, fine root production, root hair length and density, stomatal traits, biomass accumulation, harvest index, mobilization of photoassimilates to pod and seed formation and filling, and carbon fixation by non-foliar photosynthesis. In this chapter, we discuss the main responses of the Phaseolus genus to drought stress.