Adaptation of common bean (Phaseolus vulgaris L) to drought .1. Root density and root efficiency

The study was conducted at the experimental station of CNPAF/EMBRAPA, Santo Antonio de Goias, GO. The objective was to examine the influence of water absorption efficiency of root (mm(3) of water used/cm of roots/day) and linear root density (cm of roots/cm(3) of soil) on drought resistance of common bean genotypes in order to support the breeding program directed for regions with water deficiency. In this study three genotypes BAT 477, Carioca, and RAB 96 were used. These genotypes were subjected to three moisture treatments, irrigated, moderated stress and severe stress. The genotypes BAT 477 and Carioca presented, under stress treatments related to irrigated, higher linear root density, in the lower soil depth, when compared to 'RAB 96'. Further, it was observed that water absorption efficiency of root increased with soil depth, independently of water deficiency levels or genotypes studied. It was superior in genotypes BAT 477 and Carioca, specially at lower soil depths.