Plant traits and yield stability of dry bean (Phaseolus vulgaris) cultivars under drought stress

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Abstract
The objective of this study was to identify traits related to growth and yield response under drought stress in the field which would show less variation than yield itself. Experiments were conducted in 1987, at Durango, Mexico and at Michigan, USA. Twenty-six dry bean genotypes were sown under supplementary irrigation and terminal drought stress. Plant samples were taken at 50% flowering, mid-pod-filling and physiological maturity. At both sites, leaf expansion rate and crop growth rate at mid-pod-filling were greatly reduced by drought stress, resulting in significant reductions in total dry matter (DM) above ground and seed yield at physiological maturity. Because of differences in the timing and intensity of the drought stress, the yield components were affected differently at each location. Total DM content at physiological maturity, harvest index and number of pods/m2 were the only traits positively correlated with yield under stress at both locations. In order to evaluate a group of genotypes for adaptation to drought on the basis of seed yield, the genotypes should be grouped according to their phenological characteristics to stress them evenly.