SOURCES OF VARIATION OF COMMON BEAN FOR DROUGHT TOLERANCE

摘要

Drought is considered the major factor limiting crop production worldwide and is responsible for heavy production losses in food legumes. Some losses are due to intermittent drought during the vegetative phase while other is due to terminal drought during reproductive development (Serraj et al. 2004). The severity of drought stress is unpredictable as it depends on many factors such as occurrence and distribution of rainfall, evaporative demands of the atmosphere and moisture storing capacity of thesoils. Moderate to high drought stress can reduce biomass, number of seeds and pods, days to maturity, harvest index, seed yield and seed weight in common bean. Management practices can contribute to a decrease in yield loss in water-deficient environments, but major progress can also be achieved through genetic improvement. Plant responses to water stress include morphological and biochemical changes that lead first to acclimation and later, as water stress become more severe, to functional damage andthe loss of plant parts (Chaves et al. 2002). In common bean, the main selection criteria for drought resistance are parameters related to plant growth and grain production. The objective of this work was to identify common bean sources of variation forbreeding for drought tolerance.