摘要
741杨的净光合速率随入射光强度增高而增大。光补偿点为700～900lx,光饱和点出现在5～5.5万lx.饱和光强下净光合速率为16.11mgC0_2·dm^(-2)·h^(-1).光合速率随叶顺序的变化趋势是,刚展开的叶片光合速率较低,最大冷光合速率出现在12～15片叶,以后又逐渐下降。光呼吸随叶顺序变化呈下降趋势。光合作用季节变化中,6～9月光合速率均较高,10月份显著下降。对照易县毛白杨的光合作用变化。模式与741杨基本一致,但光合速率值低于741杨,这与它们在生长上的差异是一致的。
The net photosynthesis of '741' poplar [P. alba×(P. davidiana + P.simonii)] leaves increased with increasing light intensity. Light compensation point ocurred at about 700-900 Lux and light saturation point occurred at about 50000-55000 Lux.The net photosynthesis was 16.11 mgCO2dm -2h-1at light saturation point.With leaves growing up, the net photosynthesis increased gradually. The maximum net photosynthesis was detected in 12th-15th leaves counting from stem tip,and then decreased downward. The gradually decreasang tendency of photo-respiration in leaves was observed from stem tip downwards. In the seasonal pattern of photosynthesis the net photosynthesis was higher from June to Semptember (12.85-16.35 mgd m-2h-1) and reduced quickly in October (7.45mgdm-2h-1). The seasonal photosynthesis pattern of '741' poplar was similar to that of Populus tomentosa Yixianensis, but the net photosynthesis were higher.
关键词
杨树
无性系
光合特性
选育
poplar '741'
net photosynthesis and seasonal pattern
leaf order
