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 irrigati on is becoming increasingly available and investigation of the effect of li mited irrigation (LI) is a research need. Only a few seasons of successful experimentation exist with LI effects. Thus, the objective of this simulati on 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 chick pea (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)) wer e simulated. Results showed chickpea crop experiences terminal drought stre ss that is started at a time between flowering and beginning seed growth (B SG). 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 rain fed conditions. Grain yield was significantly increased with LI compared to rainfed conditions. Grain yields were reached to 60, 75 and 90% of grain y ield simulated under full-irrigated (generally requires five irrigations) c onditions. In LI with one irrigation its application at BSG, and in LI with two and three irrigations, application of first irrigation at flowering an d 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 on e, two and three irrigations, respectively. In LI systems with two and thre e irrigations it was required to a higher plant density (38 or 50 plants m( -2)) to capture and to use applied water more efficiently. (C) 2001 Elsevie r Science B.V. All rights reserved.