抗旱性不同品种的小麦叶片中光合电子传递和分配对氮素水平的响应

在大田控制条件下，以植物叶片气体交换和叶绿素荧光测定相结合的方法，研究抗旱性不同品种冬小麦拔节期叶片的光合电子传递及激发能利用分配对氮素响应的结果表明，施氮可提高抗旱性不同品种小麦叶片天线色素吸收光能的能力，虽然氮素不能改变激发能在光合碳还原（PCR）和光合碳氧化（PCO）之间的分配比例，但可提高PSⅡ总电子传递速率（JF）和Pn。低氮下不同品种小麦叶片的热耗散比例有差异，但中高氛下叶片之间无显著差异。旱地品种的鼻值随氮素水平的提高而先增加后下降，而水地品种则表现为持续升高：2个小麦品种的叶片J0值随氮素水平的提高而呈持续升高的变化趋势。氮素对叶片PSⅡ反应中心活性有影响．而不同抗旱性品种之间亦有差别，说明施氮可改善小麦叶片热耗散和光化学反应对激发能的竞争关系，从而增强光合机构的自我保护能力。

Responses of Photosynthetic Electron Transport and Partition in the Winter Wheat Leaves of Different Drought Resistances to Nitrogen Levels

The responses of photosynthetic electron transport and excitation energy distribution in winter wheat leaves at the jointing stage to nitrogen levels were studied in the field experiment, both leaf gas exchange parameter and chlorophyll fluorescence were measured. The light energy absorbed by antenna pigment of both cultivars increased with the treatment of nitrogen. Although nitrogen could not obviously change the distribution proportion of photosynthetic carbon reduction and photosynthetic carbon oxidation, nitrogen could increase JF of PSⅡ and photosynthetic rate. The heat dissipation proportion in different winter wheat cultivar leaves was significantly different under low nitrogen condition. But there were no obvious differences in leaves under middle or high nitrogen condition. JF of dryland cultivar increased with the increasing levels of nitrogen at first and then decreased, while JF of watered cultivar increased continuously with the increasing levels of nitrogen. J0 of the two cultivars also increased continuously with the increasing levels of nitrogen. Nitrogen could affect PSⅡ activities of both cultivars, and there were significant differences between the two cultivars. Nitrogen application improved the competition between heat dissipation and photo-chemic reaction and enhanced the self-protection ability of photosynthetic apparatus.