A MODEL OF THE TEMPERATURE AND SOLAR-RADIATION EFFECTS ON SPRING WHEAT GROWTH AND YIELD

A simple mechanistic model was developed to analyze the effects of temperature and solar radiation on spring wheat (Triticum aestivum L.). This model uses relatively few, conservative relationships to define leaf-area development as a function of temperature, biomass accumulation as a function of intercepted radiation, and seed growth as calculated from a linear increase in harvest index with time. Using daily weather observations of solar radiation, minimum temperature, and maximum temperature over a 10-year period at Gilat, Israel, a comparison of yields between model simulations and field observations was made. The simulations highlighted the influence of temperature on the development of crop leaf area, accumulated biomass, and grain-yields. Temperature especially influenced the duration of ontogenetic events, with cool temperature being clearly advantageous for increasing environmental yield potential of wheat. For unstressed wheat crops, the simple, mechanistic model accounted for much of the variability in grain-yield among seasons.