Use of the crop critical temperature in irrigation scheduling of corn and soybean

Kansas irrigators are becoming more conscious about water usage. Use of the infrared thermometer to evaluate water stress in plants could possibly simplify irrigation scheduling. The overall objective of this research was to investigate the utility of the crop canopy temperature for evaluating levels of crop water stress and scheduling irrigation.;Regression analyses for the canopy temperature (T;The regression equations developed can be used to find the critical temperature of the crop under a predefined soil moisture depletion level by knowing the T;Evaluation of the use of CWSI in scheduling irrigation of corn and soybean revealed that the CWSI only indicates the onset of water stress and nothing about the soil-water status. No direct relationship between CWSI and DEP was found. When CWSI was evaluated as a function of DEP and other climatic variables, results revealed that the GDD in corn, and the solar radiation (RAD) and WIND in soybean had significant contributions in the equation with low regression coefficients. Finally, it can be said the CWSI suffers from complications that limit its applicability under a wide range of environmental conditions. Reliable prediction of irrigation needs seems only possible when stress has developed and the CWSI has started to increase rapidly.;The relationship between the plant temperature and the soil water content was investigated, taking into consideration the effects of microclimate and plant physiological factors. The potential use of Crop Water Stress Index (CWSI) as a tool for irrigation scheduling was evaluated. A simplified model for predicting canopy temperature under field conditions was developed for scheduling irrigation of corn and soybean under Eastern Kansas climatic conditions.