Field Crop Response to Water Deficit Stress: Assessment Through Crop Models

Abstract

Improving water productivity is a major concern globally and more problematic in arid and semiarid regions. Decision support system based on crop simulation models can be a handy tool for improving water use efficiency. In this chapter, we have described and compared how water stress factor is quantified in seven widely used crop models, viz. DSSAT, APSIM, FAO-AquaCrop, InfoCrop, CropSyst, STICS and WOFOST. In general, these models use either threshold of soil water availability or ratio of actual to potential transpiration approaches as a measure of water stress. Further, the mechanisms by which these models account for effect of water stress on crop phenology, leaf/canopy growth, dry matter production and its partitioning are discussed. The chapter ends with reviews of crop model intercomparison for simulating crop performance under water deficit conditions. Achieving enhanced water use efficiency by optimizing crop water use through crop simulation models is a challenging task. Inaccurate and oversimplified quantification of crop water stress and its effect on growth and development of crop is a major reason for poor performance of current crop models under water-limited environments. However, incorporation of the improved understanding of physiological effects of water deficit stress on crop growth and development in the current crop growth models has the potential to adequately simulate the crop water productivity under water-shortage environments.