Application of Imitation Leaf Method to Detect WaterStress of Winter Wheat

摘要

Optimum water management and irrigation require timely detection of crop water condition.Usually crop water condition can be indicated by crop water stress index (CWSI), which can beestimated based on the measurements of either soil water or plant status. Estimation of CWSI bycanopy temperature is one of them and has the potential to be widely applied because of its quickresponse and remotely measurable features. To calculate CWSI, the conventional canopy-temperature-based model (Jackson's model) requires the measurements or estimation of canopytemperature, the maximum canopy temperature (Tcu), and the minimum canopy temperature (Tcl).Because extensive measurements are necessary to estimate Tcu and Tcl, its application is limited.In this study, by introducing the temperature of an imitation leaf (a leaf without transpiration, Tp), westudied the possibility to replace Tcu by Tp and reduce the included parameters for CWSIcalculation. Field experiments were carried out in a winter wheat (Triticum aestivum L.) field inLuancheng area, Hebei Province, where was the main production area of winter wheat in China. Sixcontrolled soil water deficit treatments were established and soil water content, leaf water potential,soil evaporation rate, plant transpiration rate, biomass, yield, and regular meteorological variableswere measured. Results indicate that the values of Tcu agree with the values of Tp with aregression coefficient r=0.9880. While the values of CWSI estimated by the use of Tp are inagreement with CWSI by Jackson's method, with a regression coefficient r=0.9985. Furthermore,CWSI estimated by the use of Tp has good relations with soil water content and leaf water potential,showing that the estimated CWSI by Tp is a good indicating for soil water and plant status.Therefore, it is concluded that Tcu can be replaced by Tp and the included parameters for CWSIcalculation can be significantly reduced by this replacement.