中文摘要：

2011年于南京对凤眼莲进行不同光处理（全天遮荫、7：00～11：00遮荫、11：00～15：00遮荫和15：00～19：00遮荫）,遮荫下光强为自然光强的70%,以全自然光为对照（CK）,处理25d,每5d分别测定生长指标、单株鲜重、单株干重、光合净光合速率（Pn）、抗氧化酶、非酶系统的总抗氧化能力（AOC）以及1,5-二磷酸核酮糖羧化加氧酶（Rubisco）活性等生理指标,以阐明光强对其生长以及适应机制,为提高凤眼莲生物量提供依据。结果显示：与CK相比,全天遮荫明显降低了叶片数量、叶面积、根长、分株和单株鲜重等生长指标,而11：00～15：00遮荫虽抑制叶片数量和子代分株的产生,但促进根的伸长和叶面积的增加,其单株鲜重比对照增加;同时,还可诱导最大净光合速率（Pnmax）,超氧化物歧化酶（SOD）、过氧化物酶（POD）、抗坏血酸过氧化物酶（APX）、谷胱甘肽还原酶（GR）和AOC活性的增加,减少了体内丙二醛（MDA）和超氧阴离子自由基（O2.-）的累积,稳定Rubisco活性,减轻光氧化胁迫。研究表明,全天遮荫不利于凤眼莲的生长,但中午遮荫有利于缓解光氧化伤害,促进其物质累积。

英文摘要：

In order to understand the growth characteristics of Eichhornia crassipes under shading treatments for different time and develop a new way to increase their biomass,we conducted the experiments during the summer natural condition in Nanjing in 2011.Several different time shading treatments（shading for whole day,shading during 7：00～11：00,shading during 11：00～15：00,shading during 15：00～19：00,the natural light condition as control） were set up for planting E.crassipes for 25 d.Every 5 day,the fresh weight per plant,the dry weight per plant,the photosynthesis parameters such as net photosynthetic rate（Pn）,antioxidant enzymes activities and 1,5-bisphosphate ribulose carboxylase oxygenase（Rubisco） activity in leaves were measured.The results showed,as compared with CK,shading whole day decreased the leaf number and ramate number,the root length,leaf area,the fresh weight and dry weight per plant,but the treatment shading during 11：00～15：00 increased the root length and leaf area.Although the leaf number and ramet number were also inhibited at this treatment.The fresh weight and dry weight per plant were a bit increase as compared to the CK.The changes of growth were closely related to the physiological characteristics.As compared with CK,the shading treatment showed that the max net photosynthetic rate（Pnmax）,superoxide dismutase（SOD）,peroxidase（POD）,ascorbate peroxidase（APX）,glutathione reductase（GR） and total antioxidant capacity（AOC） activities of leaves during shading from 11：00 to 15：00 were higher than those of CK and exhibited a decrease of malondialdehyde（MDA） content and superoxide radical production rate,which was helpful to remove reactive oxygen species（ROS） to reduce the oxidation injury at noon;The effect on the Rubisco activity of 11：00～15：00 shading was similar to that of the CK,showed the stable activity of Rubisco.It can be seen that E.crassipes is belong to sun plants.So shading treatment whole day would inhibit the growth