WheatPot: A simple model to simulate grain yield potential of spring wheat I- Model description and evaluation

A simple mechanistic crop growth simulation model “WheaPot” was developed for simulating site-specific wheat yield potential. The model simulates critical phonological stages and dry matter production as a function of temperature and solar radiation. Crop aspects of the model including developmental stages, dry matter production and grain yield are modulated in sub-models. The model requires inputs of site mean monthly weather data (minimum and maximum temperatures in ˚C) and photosynthetically active radiation (PAR in MJ m-2), and plant characteristics such as sowing date, required growing degree days (GDD) for vegetative and reproductive phases, radiation use efficiency (RUE in g MJ-1), and harvest index (HI). The model was verified using different experiments, which were carried out in several locations in Khuzestan province in 2003-2004 and 2004-2005 growing seasons. Comparison of simulated and measured values under non-limiting conditions indicated satisfactory performance of the model in predicting anthesis and maturity dates, and a fair prediction of dry matter production and grain yield with root mean square error (RMSE), 3.5 d, 4 d, 0.65 t ha-1 and 1.69 t ha-1, respectively. The model proved as a useful tool for a rough estimation of wheat yield potential at regional level where there is no access to daily weather data.