Adaptation of spring-sown chickpea to the Mediterranean basin. II. Factors influencing yield under drought

Abstract

Drought during the late vegetative and reproductive stages of development i the major constraint to the productivity of spring-sown chickpea in the rainfed farming systems of West Asia and North Africa. This paper examines the contribution of crop traits to yield under drought and determines the relative contributions of drought escape, yield potential and a drought response index (DRI) to such yield. In years with mild drought (1986/87 and 1987/88), high biomass, high yield potential and high harvest index were highly correlated with grain yield. During the severe drought of 1988/89, early flowering and low straw yield, high harvest index, yield potential, pod and seed number and seed mass were correlated with rainfed grain yield. Differences among chickpea cultivars in rainfed (drought) yield were partitioned into drought escape, yield potential and DRI. Drought escape accounted for 41% in 1986/87, 37% in 1987/88 and 69% in 1988/89; yield potential accounted for 47%, 37% and 1%, respectively; and DRI accounted for 4%, 17% and 17% of the variations, respectively. The three factors combined explained an average of 90% of the variability in grain yield. The DRI was used to quantify tolerance or susceptibility of a cultivar independently of drought escape (early flowering) and yield potential. Of the traits which were significantly associated with drought yield, high harvest index, large number of pod and high seed mass were associated with drought escape (early flowering), while deep root system, high leaf water potential at dawn and large number of seeds were associated with drought tolerance (DRI).