异质光环境中旱柳的光截取和利用反应

比较了不同光环境中旱柳枝，叶的生物量分配，形态特征，光能利用和水分特征。（1）阳性枝的枝重比显著大于全不遮荫枝；阴生枝的枝重比显著小于全部遮荫枝，而叶重比恰好相反。（2）阳生枝与全不遮荫枝的形态特征无显著差异。阴生枝的叶面积比率，比枝长和单位枝长叶数都显著大于全部遮荫枝，因而阴生枝的截光潜力大于全部遮荫枝。（3）阳性枝和阴生枝的植冠生产力指数分别显著大于全不遮荫枝和全部遮荫枝，因此，异质光环境中旱柳植株对光资源的利用效率大于同质光环境，（4）阳生枝的水分饱和亏缺和失水系数都显著小于全不遮荫枝，这暗示，前者的抗旱保水性大于后者。

LIGHT INTERCEPTION AND UTILIZATION IN RESPONSE TO HETEROGENEOUS LIGHT ENVIRONMENT IN SALIX MATSUDANA

The plasticity of biomass allocation, morphology, light utilization and hydraulic features was compared between the Salix matsudana branches growing under the contrasting light environments. (1) Branch weight ratio( BWR ) was higher in the branches growing under unshading condition and connecting to different branches under shading condition(Bhl) than that in the branches of the plants entirely growing under full sunlight(Bhh); BWR was lower in the branches growing under shading condition and connecting to different branches under unshading condition(Blh) than that in the branches of the plants entirely growing in shading condition(Bll), while leaf weight ratio followed the opposite direction.(2) There were no significant differences in morphology between Bhl and Bhh; leaf area ratio, specific branch length and leaves per branch length were higher in Blh than those in Bll. Thus, Blh had higher potential to capture light than Bll.(3) Canopy productivity indices in Bhl and Blh were larger than those in Bhh and Bll, respectively. This implied that light use efficiency of the S. matsudana branches was higher in heterogeneous than homogeneous light conditions.(4) Water saturated deficit and losing water coefficient were smaller in Bhl than those in Bhh, suggesting that Bhl had higher holding water and resistant drought ability than Bhh.