【摘要】 根据田间实测资料分析了小麦水分利用效率的综合指数—Ｐ／Ｅ。水分利用效率的变化是光合和蒸腾综合作用的结果。影响这种变化的主要因子为光照、相对湿度、气孔传导率以及土壤的肥力状况等。分析表明，作物的“午休”现象是农作物实现水分利用最优的一种适应性调节更多还原

【Abstract】 According to the data measured in field , a composite index of water use effciency (WUE)-P/E was analysed in wheat. The variation of WUE was resulted from the joint effects of photosynthesis and transpiration. The main factors affecting the variation of WUE are solar light intensity, relative humidity, stomatal conductance and the fertility of soil. It is shown that the phenomenon of “midday depression” in crops is an adaptive adjustment for optimization of WUE.更多还原