杏-紫花苜蓿复合系统中紫花苜蓿的光合和蒸腾特性研究

以杏-紫花苜蓿复合系统中紫花苜蓿为研究对象,利用Li-COR 6400便携式光合作用仪测定其光舍和蒸腾速率,结果表明:(1)杏-紫花苜蓿复合系统中,杏树行中间测点的光照度日变化规律与对照一致,都是单峰曲线,但是峰值低于对照.树行的东西冠下测点的日变化规律是对称的,前者上午出现峰值,后者下午出现峰值.树行中间、东林冠下和西林冠下日平均光照度比对照分别减小28.0%,61.9%和67.2%;(2)随着遮荫强度的增加,紫花苜蓿的光合速率降低,光饱和点、光补偿点和最大净光合速率等光合参数值相应减小;(3)杏-紫花苜蓿复合系统中紫花苜蓿的光合速率和蒸腾速率均降低,日变化曲线也发生变化.

Study on photosynthetic and traspiration chanacteristics of Medicago sativa in Prunus armeniaca-Medicago sativa agroforestry system

The photosynthetic and transpiration characteristics of Medicago sativa in Prunus armeniaca and Medicago sativa tree-grass system were studied using the Li-COR 6400 portable photosynthetic system. The results were as follows; ( 1 )The diurnal variation of light intensity at the middle experimental site between the apricot rows demonstrated a curve with one peak, the same as the control, but the value of light intensity on the peak was lower than that of the control. The diurnal changes of light at the east and west sites were symmetrical. The peak of the former appeared in the morning, and that of the latter in the afternoon. The average diurnal light intensities at the middle site, east rows and west rows were 28.0% ,61.9% ,67.2% lower than that of the control, respectively; (2) Different light environments were simulated with shading treatments. The photosynthetic rate of Medicago sativa decreased steadily, and the value of light saturation point (LSP) , light compensation point (LCP) and maximum net photosynthetic rate ( Pmax ) decreased , too; ( 3 ) The photosynthetic rate and transpiration rate of Medicago sativa in the tree-grass system declined, the regularity of their curves also changed.