施氮量对超高产冬小麦灌浆期旗叶光响应曲线的影响

Effects of nitrogen application rate on light-response curves of flag leaves in super-high yielding winter wheat at grain filling stage

为冬小麦超高产栽培的氮肥管理提供技术支撑,在大田条件下研究了施氮量对超高产冬小麦灌浆期旗叶光响应曲线的影响。采用开放式气路测定了小麦旗叶的净光合速率、气孔导度、胞间二氧化碳浓度、蒸腾速率等相关指标,并运用"米式方程"对旗叶净光合速率进行了模拟,计算了光响应曲线的特征参数。结果表明,在0～300kg/hm2施氮范围内,随着光照强度的增加,各处理的旗叶净光合速率、气孔导度、蒸腾速率均随之增加,而胞间二氧化碳浓度却随之降低,但是在375kg/hm2施氮水平下旗叶的净光合速率、气孔导度、蒸腾速率的增加和胞间二氧化碳浓度的降低反而低于300kg/hm2施氮水平,表明合理的氮素水平对超高产小麦灌浆期旗叶的光响应曲线有明显的调节作用。在合理的施氮范围内,增施氮肥小麦旗叶在整个灌浆期内的最大净光合速率随之增加。在本试验条件下,超高产麦田的适宜施氮量为300kg/hm2。

In order to provide a standard consortium for nitrogen fertilizer management of super-high yielding winter wheat cultivation, different nitrogen application rates were tested in concomitant with their effects on light-response curves in the flag leaves were studied. The experiments were conducted at grain filling stage of super-high yielding winter wheat under field conditions. Net photosynthetic rate （Pn）, stomatal conductance （Gs）, intercellular CO2 concentration （Ci） and transpiration rate （Tr） in flag leaves of super-high yielding winter wheat were measured in an open-circuit gas channel system. Moreover, Pn was simulated by the Michaelis-Menten model, and then characteristic parameters of the light response curves were calculated. The results showed that Pn, Gs andTr of flag leaves among all treatments increased with the increasing of the light intensity in the range of 0 -300 kg/hm^2 nitrogen application rate, but Ci decreased. However, the increasing of Pn, Gs and Tr and the decreasing of Ci under the nitrogen level of 375 kg/hm^2 were lower than that under the nitrogen level of 300 kg/hm^2 , which indicated that reasonable nitrogen application has significant regulating effect on light-response curves of flag leaves in super-high yielding winter wheat at grain filling stage. It can be concluded that at the rational range of nitrogen application, the maximum net photosynthetic rate （Pnmax） of the flag leaves with high yield increased in the whole grain filling stage with the increasing of nitrogen fertilizer. Under this experiment condition （ N 300 kg/hm^2 application ）, the highest grain yield was observed and hence suggested for super-high yielding winter wheat cultivation.