A simulation study of chickpea crop response to limited irrigation in a semiarid environment

In West Asia and North Africa (WANA) including northwest (NW) Iran irrigation is becoming increasingly available and investigation of the effect of limited irrigation (LI) is a research need. Only a few seasons of successful experimentation exist with LI effects. Thus, the objective of this simulation study was to examine potential long-term benefits of limited irrigation in NW Iran in terms of grain yield. To do this, a simple, mechanistic chickpea (Cicer arietinum L.) model and 16 years of weather data of Maragheh (NW Iran) were used. Three LI systems with one, two and three irrigations and each with three plant population densities (25, 38 and 50 plants m−2) were simulated. Results showed chickpea crop experiences terminal drought stress that is started at a time between flowering and beginning seed growth (BSG). This terminal drought stress severely reduces grain yield by 67%, from 2766 kg ha−1 under full-irrigated conditions to 909 kg ha−1 under rainfed conditions. Grain yield was significantly increased with LI compared to rainfed conditions. Grain yields were reached to 60, 75 and 90% of grain yield simulated under full-irrigated (generally requires five irrigations) conditions. In LI with one irrigation its application at BSG, and in LI with two and three irrigations, application of first irrigation at flowering and application of one or two other irrigations when fraction of transpirable soil water dropped to 0.5 in the root zone resulted in higher grain yield. Water use efficiency was, also, increased with LI by 28, 39 and 52% for one, two and three irrigations, respectively. In LI systems with two and three irrigations it was required to a higher plant density (38 or 50 plants m−2) to capture and to use applied water more efficiently.