An experiment was conducted to study the morphological and physiological responses of Sophora japonica seedlings to different levels of irradiance ( 15% , 30% , 50% , and 100% ). With increasing light intensity, the total leaf area and seedling height of S. japonica increased significantly, while the total biomass and diameter at ground level had no significant differences under 30% -100% sunlight, which were significantly higher than those under 15% sunlight. At low levels of irradiance, S. japonica could improve light interception by allocating high biomass to leaves and increasing specific leaf area, leaf area ratio, and ratio of leaf area to root mass, which were favorable to the increase in photosynthetic leaf area. The biomass ratio of supporting organs of S. japonica increased with decreasing sunlight in order to support the increased above-ground biomass. At high levels of irradiance, S. japonica could keep the balance of water uptake and transpiration by increasing root biomass ratio (ratio of root mass to whole-plant mass) and root-shoot ratio and decreasing leaf biomass ratio, specific leaf area, and ratio of leaf area to root mass. The maximum net photosynthetic rate, light saturation point and light compensation point increased significantly with increasing levels of irradiance. With increasing light intensity, total chlorophyll and carotenoid contents of S. japonica seedlings decreased significantly, while chlorophyll a/b ratio enhanced significantly. S. japonica seedlings can acclimate to different light situations, with good morphological and physiological adaptations.%通过对槐树盆栽幼苗的遮阴试验,分析测定了光强对槐树幼苗形态和生理特性的影响.结果表明:随着光强的增大,其总叶面积和株高均显著降低,30％～100％光强范围内,总生物量和地径差异不显著,但均显著大于15％处理.低光强下,植株通过增大叶生物量比、比叶面积、叶面积比和叶根比,以增大光合叶面积,提高捕光能力；增大支持结构生物量比,以增加支持叶生物量；在高光强下,植株通过提高根生物量比和根冠比,降低叶生物量比、比叶面积和叶根比,保持了水分吸收和蒸腾的平衡.随着光强的增大,植株最大净光合速率、光饱和点和光补偿点均显著增大.槐树幼苗的总叶绿素和类胡萝卜素含量随着光强增大而显著降低,而叶绿素a/b随着光强的增大而显著增大.说明槐树幼苗对光强的形态和生理适应性较强,能够适应较广的光强范围.
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