Book Description

The assumptions relating to the effect of water stress on crop growth inherent in the crop simulation model (Stockle & Campbell, 1985) used here, appear to be valid when applied to Cerrado conditions. Temperature and light effects on photosynthesis are considered in the calculation of a non-stressed photosynthetic rate, which is dependent on the amount of photosynthetically active radiation intercepted by the canopy. Thus, model predictions are sensitive to the predicted partitioning of potential evapotranspiration. Predicted leaf area indices and dry a matter accumulation over time compared well with measured data. Dry matter and leaf area were overpredicted in the most extreme water stress treatment, possibly due to soil fertility/water interactions not represented in the model. Harvest index was related more to water stress accumulated throughout the growing season, than to water stress accumulated during pollination, as was suggested by Stockle & Campbell (1985). Hourly predicted leaf water potential changes and corresponding changes in transpiration and photosynthetic rate represented the dynamics of water stress realistically and were consistent with expectations.