A simple model for chickpea growth and yield A. Soltani * , K. Ghassemi-Golezani, F.R. Khooie, M. Moghaddam Department of Agronomy, Faculty of Agriculture, University of Tabriz, Tabriz, Iran Accepted 18 February 1999 Abstract Chickpea (Cicer arietinum L.) is a major crop in cool and cold semi-arid environments of Iran, where yield is limited by climatic factors, water availability and genotype. A robust crop model can assist in evaluation of biophysical limitations in crop yield. The objective of this study was, therefore, to develop a simple mechanistic model for chickpea to be used in assessing production limitations. The model simulates crop phenology, development of leaves as a function of temperature, accumulation of crop biomass as a function of intercepted radiation, dry matter accumulation of grains as a function of time and temperature, and soil water balance. Phenology, leaf growth and senescence and biomass production were made sensitive to soil water content. The model uses a daily time step and readily available weather and soil information. The model was tested using independent data from a range of Iran's environmental conditions. In most cases, simulated grain yield were similar to observed yield and ranged from 0.4 to 3.25 t/ha. The root mean square error was 0.24 t/ha. The agreement between simulated and observed grain yields showed the robustness of the model in predicting chickpea growth and yield for both irrigated and rainfed conditions. It was concluded that the model can be used in simulation studies of potential yield and production limitations. # 1999 Elsevier Science B.V. All rights reserved. Keywords: Chickpea; Crop modeling; Crop physiology; Grain yield; Simulation; Water balance 1. Introduction Chickpea is one of the major pulse crops throughout the world. It is cultivated on a large scale in arid and semiarid environments, and has considerable impor- tance as food, feed and fodder (Singh, 1997). In Iran the climate of the chickpea producing area is largely cool and cold semi-arid with a high variability in rainfall. Chickpea cultivars used in Iran have been subjected to little breeding work, and consequently, chickpea yield in Iran is limited by climatic factors, water availability and genotype. Biophysical limitations in crop yield at any location can be assessed by coupling a crop simulation model to long-term sequences of weather data and generating probability distributions of simulated yield. Simple models that are easy to interpret and use have been developed and utilized successfully for examining yield potential and yield limitations. A simple and robust crop model for soybean was developed by Sinclair (1986) using a phenomenological and phy- siological framework. This modeling approach has been generalized and used to examine yield potential and production risks in other species, such as cowpea and black-gram (Sinclair et al., 1987), spring wheat (Amir and Sinclair, 1991), maize (Muchow and Field Crops Research 62 (1999) 213±224 *Corresponding author. 0378-4290/99/$ ± see front matter # 1999 Elsevier Science B.V. All rights reserved. PII:S0378-4290(99)00017-9