Evaluation of a crop growth-water balance model for analysing wheat responses to climate- and water-limited environments

Performance of a combination of a simple and universal crop growth simulator (SUCROS of van Keulen et al., 1982) with a water balance model (WBM of Arora et al., 1987) with some modifications was evaluated for analysing wheat yield responses to variable climatic and water supply regimes. Crop aspects of the model include gross CO2 assimilation, maintenance respiration, assimilate partitioning, dry biomass production, green area growth and senescence. Water balance aspects considered are soil evaporation (E), canopy interception evaporation (I), crop transpiration (T), and deep drainage (D). Extensive evaluation of the model showed close agreement between measured and simulated grain yield for most water supply regimes with yields ranging from 0.6 to 6.2 t ha(-1). Probability distribution analysis of grain yield indicates low yields with large Variance in rainfed environments. Supplemental irrigation and higher soil water retentivity increases mean grain yield and reduces the effects of annual rainfall variability. This study suggests that the model can be applied for optimising water use at field scale. (C) 1998 Elsevier Science B.V. All rights reserved.