A Single Supplementary Irrigation Can Boost Chickpea Grain Yield and Water Use Efficiency in Arid and Semiarid Conditions: A Modeling Study

Chickpea (Cicer arietinum L.) is an agronomically important legume in Iran that is grown predominantly as a rainfed crop due to severely limited supplies of water suitable for irrigation. Long‐term daily weather data for the period of 1982 to 2012, were collected for 12 locations in Khorasan‐Razavi province in northeastern Iran with a cold semiarid and arid climate. A crop simulation model was used to investigate the effect of a single irrigation (at flowering or pod‐filling stage) under a range of sowing dates on the yield and water use efficiency (WUE) of chickpea. The results showed that supplementary irrigation substantially increased grain yield at all the locations. Across all locations and sowing dates, supplementary irrigation increased modeled grain yield 41 to 139% for irrigation at flowering stage (R1), and 13 to 66% for irrigation at the pod‐filling stage (R3). Supplementary irrigation also increased WUE as 12 to 121% at R1. Delaying sowing until late April, as compared to early to mid‐February, resulted in a 51% reduction in modeled yield. Averaged across locations and irrigation regimes, earlier sowing increased WUE over late sowing (4.9 vs. 3.4 kg ha−1 mm−1). It was concluded that early sowing (early and mid‐February) combined with a single irrigation applied at anthesis would, over the course of several years, improve average productivity and WUE of rainfed chickpea by 65 and 51%, respectively. Core Ideas SSM‐legume model can be used for evaluation of production limitation efficiently. Early sowing enabled chickpea to better exploit rainfall during crop season. One single supplementary irrigation substantially increased grain yield. Early sowing with one‐time irrigation applied at flowering hugely improve water use efficiency.