Effects of nitrogen application rate on light-response curves of flag leaves in super-high yielding winter wheat at grain filling stage
Effects of nitrogen application rate on light-response curves of flag leaves in super-high yielding winter wheat at grain filling stage
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作者：
Sun Xu
为给超高产冬小麦栽培氮肥管理提供依据，在田间条件下，对超高产冬小麦灌浆期不同施氮量及其对旗叶光响应曲线的影响进行了试验研究。在开路气路系统中测定了超高产冬小麦旗叶的净光合速率(Pn)、气孔导度(Gs)、胞间CO2浓度(Ci)和蒸腾速率(Tr)，并用Michaelis-Menten模型模拟了旗叶的净光合速率。结果表明，在0~300 kg/hm2施氮量范围内，随着光强的增加，各处理旗叶的Pn、Gs和Tr增加，Ci降低，但在375 kg/hm2施氮量下，Pn、Gs、Tr的增加和Ci的下降幅度低于300 kg/hm2施氮量处理。结果表明，合理施氮对超高产冬小麦灌浆期旗叶光响应曲线有显著的调节作用，在合理施氮量范围内，整个灌浆期高产旗叶的最大净光合速率(Pnmax)随施氮量的增加而增加，在本试验条件下(施氮量300 kg/hm2)籽粒产量最高，适合超高产冬小麦栽培。
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/hm2 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/hm2 were lower than that under the nitrogen level of 300 kg/hm2,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/hm2 application),the highest grain yield was observed and hence suggested for super-high yielding winter wheat cultivation.