Determining the optimum planting date of chickpea in Kermanshah province using modeling approach

Crop simulation models are useful tools for determination of optimum strategies for crop management and sustainability of the agricultural ecosystems. The aim of this study was to evaluate the effect of different planting dates on grain yield, biological yield and water use efficiency of chickpea (Bivanij cultivar) under rainfed conditions at five locations in Kermanshah province. For this purpose, the SSM-Chickpea model along with historical daily weather data for the period of 1985–2014, were used. The results showed that early sowing date increased leaf area and biological yield and eliminated terminal drought stress. The highest and lowest grain yield was obtained on 20 Febraury and 4 March sowing dates with 1269 and 446 kg ha-1, respectively. The delayed sowing date substantially reduced grain yield by 64%. Furthermore, the highest and lowest biological yield was obtained on 20 Febraury (3448 kg ha-1) and 21April (2217 kg ha-1). On the other hand, the greatest water use efficiency was obtained on 20 Febraury (6.6 kg ha-1 mm-1). Overall, early sowing dates resulted in increased duration of growing season and seasonal rainfall which concurrency resulted in higher yield and WUE. Hence, early sowing chickpea is recommended over late sowing in arid and semi-arid areas of the study locations which are facing with lack of adequate and poor distribution of rainfall.