喷灌田间小气候对作物蒸腾影响的田间试验研究

为准确评价喷灌水利用率，以地面灌为对照，利用热平衡茎流计对喷灌冬小麦和夏玉米的蒸腾速率进行了连续2年监测，结果表明，喷灌对田间小气候的改善使得作物的蒸腾受到明显抑制，就一次灌水而言，从喷灌启始至蒸腾抑制作用消失，喷灌处理冬小麦蒸腾量仅占地面灌处理的7％～14％，由冠层截留水量蒸发导致的蒸腾抑制量为1.7～4.1mm；夏玉米喷灌处理蒸腾量占地面灌处理的23％～42％，蒸腾抑制量为 0.5～2.8mm。将截留水量与蒸腾抑制量进行比较可知，喷灌夏玉米冠层截留作用可能产生一定量的水分损失，而冬小麦冠层截留水量则在小麦耗水过程中是完全有效的。

Field evaluating the effect of microclimate modification resulted from sprinkler irrigation on crop transpirations

The transpiration rates were measured using heat sap flow gauges during growing season of winter wheat and summer corn under sprinkler irrigation condition to evaluate the efficiency of irrigated water. The experimental results demonstrated that crop transpiration was obviously suppressed by microclimate modification resulted from sprinkler irrigation. For one irrigation event, the amounts of transpiration of winter wheat and summer corn were only 7%-14% and 23%-42% of those under surface irrigation respectively, and the amounts of transpiration suppression caused by evaporation of canopy intercepted water were 1.7mm-4. 1mm and 0.5mm-2.8mm respectively, from the beginning of spraying to the vanishing of transpiration suppression. The amounts of transpiration suppression increased linearly with daily solar radiation and decreased linearly with daily average relative humidity. The effect of daily average air temperature was not significant. Transpiration suppression can entirely compensate the water losses caused by canopy interception for winter wheat, while the losses can only be partially compensated for summer corn.