太湖中2种大型沉水被子植物适应低光能力的比较

测定不同光强下太湖沉水植物苦草和马来眼子菜的光合参数以及比较两者低光适应能力差异的结果表明：在5％自然光和100％自然光下，马来眼子菜的光合效率和电子传递速率（ETR）均下降，而苦草在大于70％自然光下开始急剧下降，叶中丙二醛（MDA）含量和膜透性变化趋势与此相反；两者最大非光化学猝灭（qNmax）随光强增大而升高，而苦草在自然光下却下降。苦草的叶绿素a／b（chla／b）值随光强的下降而减小，而马来眼子菜的却无明显变化，但后者类胡萝卜素／叶绿素a（car／chla）的值随光强增加而显著增大。这表明苦草适应低光的能力更强，与两者在白然水体中的空间分布一致。

Comparison of Adaptive Capacity to Low Light Intensity of Two Angiosperm Submerged Macrophytes from Taihu Lake

Adaptive capacity to low intensity of two common submerged macrophytes from Taihu Lake was investigated in this paper by conducting a shading experiment. The results showed that the photosynthesis efficiency and electron transport rate (ETR) in Potomageton malaianus Miq. decreased at 5% and 100% of natural light intensity. Those in Vallisneria spiralis L. showed excellent adaptive capability to reduced light in terms of continuous increase over all the treatments,but it suffered sever photoinhibition above 70% of natural light intensity. The maximum non-photochemical quenching (qNmax) in P. malaianus rose over all treatments,but that of V. spiralis decreased under the control light. Pigmentation analysis also showed a distinct acclima-tion of pigment ratios. The tendency of the carotenoids/chl a (car/chl a) value in P. malaianus was correlated to the increased light without significant change of the chl a/b value,but that was reverse in V. spiralis. Furthermore,the results of the malondialdehyde (MDA) content and membrane permeability also supported above results that those of P. malaianus enhanced greatly at the 5% and 100% of natural light intensity,whereas those of V. spirali increased above 70% of natural light intensity. These results showed that V. spiralis could be better adaptive to the low light,which was accordant with the spatial variation of two species in natural waters.