氮肥施用对旱地秸秆覆盖冬小麦旗叶生理特性的影响

为给旱地保护性耕作小麦水肥高效利用提供理论依据和建立合理的氮素管理模式,在渭北旱塬研究了秸秆覆盖下氮肥用量及施用时间对小麦旗叶光合特性及衰老的影响。结果表明,施氮量没有显著影响小麦花后旗叶的叶绿素相对含量(SPAD值)、光合速率和蒸腾速率,高氮用量明显增加小麦旗叶中丙二醛的累积,加速了旗叶衰老。氮素分次施用有延缓小麦旗叶SPAD值下降从而延缓旗叶衰老的作用,但是没有显著影响小麦旗叶的光合速率和蒸腾速率。秸秆覆盖较不覆盖显著提高了小麦旗叶的SPAD值、光合速率和蒸腾速率,并延缓了旗叶的衰老,进而提高了灌浆后期籽粒的灌浆速率,有增加千粒重的趋势。小麦籽粒产量变化范围为3 123~3 714kg·hm-2,试验年度氮素调控和秸秆覆盖均没有显著影响小麦的产量。

Influence of Nitrogen Application on Physiological Traits of Wheat Flag Leaf under Straw Mulching on Dryland

Nitrogen application plays an important role in slowing leaf senescence of wheat,and reasonable regulation of nitrogen application could increase wheat yield and helps improve the water and fertilizer use efficiency. This article studied the influence of nitrogen application amount and application rate on wheat flag leaf photosynthetic characteristics and leaf senescence under straw mulching on drylands in Weibei highland. The results showed that nitrogen application rate did not affect wheat flag leaf chlorophyll content(SPAD value),photosynthetic rate and transpiration rate. But higher nitrogen application rate significantly increase the amount of MDA accumulation and accelerated flag leaf senescence of wheat. Nitrogen split application had the trend to maintain SPAD value and alleviate senescence of flag leaf of wheat,however,there's no significant effect on flag leaf photosynthetic rate and transpiration rate of wheat. The straw mulch significantly increased the SPAD value of the flag leaf,photosynthetic rate and transpiration rate of wheat,and delaying senescence of flag leaf at the late stage of grainfilling,thus increased grain filling rate of wheat. Grain yield of wheat varied from 3 123 kg·hm^-2 to 3 714 kg·hm^-2,nevertheless,both nitrogen regulation and straw mulching had no significant effect on grain yield of wheat in the experimental year. Therefore,the effects of nitrogen regulation on the yield of winter wheat under straw mulching on dry land needs further study.