桐麦间作系统小麦蒸腾速率和水分利用效率变化的研究

Changes of Transpiration Rates and Water Use Efficiency of Wheat in the Inter Cropping System of Paulownia Wheat

对桐麦间作系统内外的对比研究表明，系统内外小麦叶面蒸腾速率从开花期至成熟期均有所增加；开花期系统内外小麦叶面平均蒸腾速率分别为５．８４，５．７２ｍｍｏｌ·ｍ－２·ｓ－１，差别不显著；从灌浆期到成熟期，系统外对照点小麦叶面蒸腾速率比系统内高，系统内外小麦叶面平均蒸腾速率比为０．８１；１１时之前，系统内泡桐东冠下点小麦叶面蒸腾速率比西冠下点高，１１时之后则反之．从开花期至成熟期，系统内外小麦水分利用效率从上午到下午是递减的，且开花期高于灌浆期，灌浆期高于成熟期．开花期内系统内外各点小麦水分利用效率差别不明显．从灌浆期至成熟期，系统内泡桐冠下点小麦水分利用效率低于冠外点．从开花期至成熟期，系统内外小麦的水分利用效率随空气中水分饱和差的增加而降低，小麦每天的平均水分利用效率与每天空气中水分平均饱和差相关系数为－０．８８．

Based on a comparative study of the wheat crops inside and outside the inter cropping system of Paulownia wheat, it was found that transpiration rate of wheat leaves increased from flowering to maturing stages both inside and outside the system. During flowering, the leaf transpiration rates were 5 84 and 5.72 mmol·m -2 ·s -1 for wheat plants inside and outside the system respectively,not significantly different. From grain filling to maturing, transpiration rate of wheat leaves outside the system was higher than that inside the system, and the ratio of the average transpiration rates inside and outside the system was 0.81. Transpiration rate of the leaves of the wheat crops below the crowns of the eastern tree belt was higher before 11 AM but lower after 11 AM than that of leaves below the crowns of the western belt inside the system. Water use efficiency of wheat leaves inside and outside the system decreased from morning to afternoon within a day from flowering to maturing, and water use efficiency of wheat leaves during grain filling was lower than that during flowering,but higher than that during maturing. During flowering water use efficiency of wheat leaves inside the system was not significantly different from that outside the system; from grain filling to maturing, water use efficiency of wheat leaves outside the system was higher than that inside the system. From flowering to maturing, water use efficiency of wheat leaves decreased as the saturated water vapor pressure deficit of the ambient air increased, the correlation coefficient between the daily water use efficiency of wheat leaves and daily saturated water vapor pressure deficit of the ambient air was -0.88.