中文摘要：

以中双9号、中油杂11号和华油杂14号油菜为材料,测定花后短柄叶光合速率及生理指标,探讨短柄叶光合衰退与叶绿素含量等因素之间的关系及其对油菜产量的影响。结果表明,油菜短柄叶光合速率随叶片衰老而逐渐降低,1,5-二磷酸羧化酶（RuBPCase）、可溶性蛋白和叶绿素含量,以及超氧化物歧化酶（SOD）和过氧化氢酶（CAT）活性均呈现出下降趋势,膜脂过氧化作用产物丙二醛（MDA）在叶片光合功能衰退过程中含量逐渐上升。油菜叶片光合衰退与RuBPCase含量、可溶性蛋白含量、叶绿素含量和SOD活性存在显著相关关系,表明光合速率的下降可能与油菜叶片衰老过程中N含量、叶绿素降解及蛋白质合成受抑制相关;SOD和CAT水平逐渐降低及MDA含量升高也表明,叶片衰老过程中氧自由基胁迫抑制光合作用。叶片光合作用与油菜单株产量的相关关系分析结果表明,油菜短柄叶光合速率,特别是短柄叶衰退的中后期光合速率是影响油菜产量的重要因素。

英文摘要：

Photosynthetic rate,chlorophyll content and enzyme activity of short-stalk leaves of rapeseed（Brassica napus） seedlings were investigated to examine photosynthesis senescence effect on yield.The materials included 3 cultivars which were Zhongshuang 9,Zhongyouza 11 and Huayouza 14.Result showed that net photosynthetic rate（Pn） decreased slightly at early stage of senescence,but decreased remarkably at later stage.Similar responses were found in ribulose 1,5-bisphosphate carboxylase（RuBPCase） content,soluble protein content,chlorophyll content,superoxide dismutase（SOD） and catalase（CAT） activities in leaves.The progressive increase of malondialdehyde（MDA） occurred at early stage of senescence.Correlations were observed between photosynthesis declining and contents of ribulose bisphosphate carboxylase,soluble protein,chlorophyll,as well as SOD activity.Result indicated that Pn decreasing might relate to nitrogen levels,chlorophyll degradation and inhibition of protein synthesis.A senescence process was associated with an increase in the oxidative stress,as revealed by lipid peroxidation and antioxidant enzyme activities.By analyzing relationship between yield per plant and Pn,short-stalk leaf photosynthetic rate was discovered to be important to yield,especially during the middle-late stages of rapeseed.