Adaptation of spring-sown chickpea to the Mediterranean basin. I. Response to moisture supply

Abstract

Chickpea is grown in spring as a rainfed crop in West Asia and North Africa (WANA) regions in areas with mean annual rainfall of not less than 400 mm but where the rainfall amount and distribution are highly variable. We hypothesized that for WANA, the best-adapted cultivars should produce high yields in years with low rainfall and be responsive to moisture supply in years with high rainfall. Studies were therefore conducted to determine whether there is genetic variability in response to moisture supply and if so, to develop breeding strategies that support our hypothesis. Chickpea cultivars of diverse origin were grown under a soil moisture gradient using a line-source sprinkler irrigation system at Tel Hadya, northern Syria during the 1986/87, 1987/88 and 1988/89 seasons. In 1986/87 rainfall (359 mm) was similar to the long-term average but temperatures in the March-May period were lower. In 1987/88 rainfall was high (504 mm); and in 1988/89, it was low (234 mm) and temperatures during the March-May period were higher than the long-term average. Rainfed mean grain yields were 0.984 t/ha in 1986/87; 1.099 t/ha in 1987/88 and 0.187 t/ha in 1988/89. Cultivars varied significantly in response of grain yield to moisture supply (3.93–9.29 kg/ha/mm in 1986/87; 2.15–8.19 kg/ha/mm in 1987/88; and 3.10–9.57 kg/ha/mm in 1988/89). Responsiveness to moisture supply (regression slope) was highly correlated with yield potential. However, the correlation between the responsiveness to moisture supply and drought (rainfed) yield was non-significant. Widely adapted (stable) cultivars (i.e. cultivars which are considered well adapted to variation in moisture supply) in 1986/87 and 1987/88 were those with high mean yield, high rainfed yields and high yield potential; and in 1988/89 when the rise in temperature in spring was fast, additional requirements for wide adaptation were early phenology and high harvest index. Chickpea cultivars with wide adaptation had deep root systems and high pre-dawn leaf water potential