中文摘要：

以甘蓝型油菜（青杂303）为研究材料，通过研究分析油菜幼苗期的生长和生理特性，旨在探讨油莱幼苗对青藏高原地区未来大气氮沉降的响应机制。实验以NH4NO3氮肥模拟大气氮沉降的NH4^-、NO3^-输入并分别喷施0、2．5、5．0g／m^2·a模拟青藏高原地区大气氮沉降增加的0倍、2倍、4倍背景。结果表明：施氮处理对油菜幼苗生长具有促进作用，油菜幼苗的地上部分干重、叶面积和株高等形态指标都发生了显著变化；随着施氮量增加油菜幼苗叶片的抗氧化酶活性增强，氮肥输入量为5．0g／m^2·a的处理组中，其幼苗叶片超氧化物歧化酶（SOD）、过氧化物酶（POD）、过氧化氢酶（CAT）活性与对照的相比均具有极显著差异。因此，反映出青藏高原地区生态系统中植物生长受到有效氮的限制，在外界有效氮输入下，对植物生长发育具有促进作用。

英文摘要：

A field experiment was established in the Tibetan plateau with the aim of investigating the effects of nitrogen deposition on Brassica napus L. growth, Morphology and Physiology, because the Tibetan plateau vulnerability to current and predicted changes in atmospheric nitrogen deposition and plants how to responses to the changes are not well understood. In this study, the simulated elevated nitrogen depositions were equivalent to 0 （ control）, 2. 5 （ treat1 ） , 5 （ treat2 ） g/m^2 · a. Brassica napus L. （ Qingza, 303 ） suitable for growing at 2800m below in the third pole were selected and growth parameters（ plant height, leaf area, LMA and above-ground biomass） and the antioxidase activities（ SOD, POD and CAT） of Brassica napus L. leaves were measured. The results showed that to some extent, the growth parameters of Brassica napus L. seedling between different treatments have significantly increased. Especially 5g/m^2 ·a treatment, a dramatic increase in leaf area and above-ground biomass compared with to control. The activity of SOD, POD and CAT of Brassica napus L. leaves were increased than that of control.