中文摘要：

【目的】氮是限制作物光合作用的重要因子,除含量之外,氮在光合器官各组分间的分配可能也是影响光合作用的重要因素。本研究从叶片尺度探究冬油菜苗期氮素在光合器官中的分配,分析不同氮水平下光合氮素利用特征及其与光合氮利用效率的关系,以揭示氮素营养影响光合氮利用效率的机制。【方法】采用田间试验,设3个施氮水平（0、180、360 kg/hm2,分别以N0、N180、N360表示）,在苗期测定最新完全展开的叶净光合速率（Pn）、氮含量、光合氮利用效率（PNUE）以及最大羧化速率（Vc max）、最大电子传递速率（Jmax）等相关生理、光合参数,并计算叶片氮素在光合器官（羧化系统、生物力能学组分和捕光系统）的分配比例。【结果】施氮明显改善冬油菜苗期的生长,显著增加了叶片数、叶面积和叶片干重,但单位叶面积干重低于不施氮处理。与N0相比,N180和N360处理的冬油菜最新完全展开叶的氮含量和Pn显著升高,其中叶片氮含量分别增加了155.0%、157.3%,Pn则增加57.6%、56.1%,N180与N360处理间无显著差异;而PNUE随施氮水平的提高而降低,与N0相比,N180和N360处理分别下降了35.6%和39.6%。施氮提高了冬油菜苗期叶片的光合能力,N180和N360处理的最大净光合速率（Pnmax）、羧化效率（CE）、最大羧化速率（Vc max）及最大电子传递速率（Jmax）显著高于N0处理。氮肥用量同样影响氮素在光合器官中的分配,与N0相比,N180和N360处理的氮素在叶片光合器官投入的比例显著降低,降低幅度分别为29.3%、34.5%;其分配比例在羧化系统（PC）、生物力能学组分（PB）及捕光系统（PL）分别降低了24.1%、23.3%、34.6%和31.0%、26.7%、38.5%。相关分析表明,叶片中羧化和生物力能学组分及光合组分氮的分配比例与PNUE均呈显著正相关关系,而与非光合组分氮分配比例呈显著负相关关系。【结论】随施氮?

英文摘要：

【Objectives】Nitrogen is one of the most important factors limiting crop photosynthesis. Besides nitrogen（ N） concentration,nitrogen allocation in the photosynthetic apparatus is also an important factor influencing crop photosynthesis. The aim of this study was to explore effects of nitrogen allocation on photosynthetic apparatus at the seedling stage of winter oilseed rape under different N levels,to analyze relationship with photosynthetic nitrogen use efficiency,and to reveal mechanism of photosynthetic nitrogen use efficiency affected by nitrogen. 【Methods】An on-farm experiment was carried out to investigate the effects of different N levels（ 0,180 and 360 kg / hm2;marked as N0,N180 and N360,respectively）. Some physiological and photosynthetic parameters（ e. g.,net photosynthetic rate（ Pn）,nitrogen content,photosynthetic nitrogen use efficiency（ PNUE）,the maximum rate of carboxylation（ Vc max） and the maximum rate of electron transport（ Jmax）） of the first fully expanded leaf were measured to calculate nitrogen allocation in the photosynthetic apparatus（ carboxylation,bioenergetics and lightharvesting components）. 【Results 】The results show that the N fertilization could significantly enhance crop growth. The leaf number,leaf area and dry matter of N treatment are significantly higher than those of the N0 treatment. Under different N levels,the leaf nitrogen contents and net photosynthetic rates of the N180 and N360treatments are increased by 155. 0%,157. 3% and 57. 6%,56. 1%,respectively,compared to those of the N0 treatment. However,photosynthetic nitrogen use efficiencies are significantly decreased,which are 35. 6% and39. 6% lower than that of the N0 treatment. The photosynthetic capacity accompanied by the N-fertilizer application is increased,and the maximum net photosynthetic rates（ Pnmax）,carboxylation efficiencies（ CE）,maximum rates of carboxylation（ Vc max） and the maximum electron transport rates（ Jmax） of the N180 and N360treatments are s