Root Growth of Four Common Bean Cultivars in Relation to Drought Tolerance in Environments with Contrasting Soil Types

Abstract

SUMMARYRoot growth of two drought tolerant and two drought sensitive bean (Phaseolus vulgarisL.) lines was compared at two locations in Colombia differing primarily in soil conditions. At Palmira, roots of drought tolerant lines reached a depth of 1.3 m, while drought sensitive lines only reached 0.8 m. These differences were associated with differences in seed yield, crop growth, canopy temperature and soil moisture extraction. Under acid soil conditions at Quili-chao, seed yields of supposedly drought tolerant genotypes were similar to those of the drought sensitive lines, and root growth of all four lines was restricted to less than 0.8 m. Drought avoidance through greater root growth and extraction of soil moisture appears to be an important drought tolerance mechanism in common beans, but its usefulness is limited where soil conditions restrict root growth.