施氮和栽培模式对半湿润农田生态系统冬小麦源特征的影响

为了探讨不同施氮水平及不同栽培模式下小麦源特征的变化,在黄土高原南部年降水量632 mm左右的半湿润区,以小偃22为供试品种,研究不同施氮水平(不施氮和施纯氮120 kg/hm2)及不同栽培模式(常规栽培、地膜覆盖、垄沟栽培、垄播覆膜)对小麦源特征的影响。结果表明,施氮能够极显著地增加小麦各生育期旗叶氮含量,其中以拔节期的影响效果最为明显;不同栽培模式对旗叶氮含量的影响效果较小;在灌浆期和成熟期,垄播覆膜和地膜覆盖两种栽培模式下旗叶氮含量均高于其他处理,其中以垄播覆膜效果较为明显,分别较常规栽培增加12%和29%。施氮条件下,冬小麦各生育期旗叶叶绿素含量均高于不施氮处理;不同栽培模式下以垄沟栽培模式下旗叶叶绿素含量最高,常规栽培最低。返青期、拔节期、开花期和灌浆期,施氮处理单株绿叶面积较不施氮处理分别增加23.4%,20.7%,15.3%和8.9%,施氮对单株绿叶面积的影响以返青期最为显著;地膜覆盖、垄沟栽培和垄播覆膜栽培模式下,单株绿叶面积明显高于常规栽培,以垄播覆膜栽培模式下单株绿叶面积最大。施氮能够显著增加开花期、灌浆旗和成熟期旗叶净光合速率(P<0.05),各栽培模式间旗叶净光合速率存在极显著差异(P<0.01),其中以垄播覆膜栽培条件下旗叶净光合速率最大。相关分析发现,增加功能叶氮含量,特别是生育后期氮含量,对籽粒产量具有重要作用。说明施氮有利于增加功能叶氮含量,提高净光合速率,进而有利于提高籽粒产量,从这一角度出发,地膜覆盖和垄播覆膜栽培应为首选栽培模式。

Effect of nitrogen fertilizer and planting modes on the source characteristic of winter wheat in sub-humid farmland ecosystem

It is of great importance to study the difference of source characteristic of winter wheat under different nitrogen fertilizations and planting modes for optimizing fertilization and planting strategies of dry-land farming on Loess Plateau.The field experiment was conducted at the south part of Loess Plateau with about 632 mm precipitation each year.Xiaoyan 22 was used as indicating crop to study the effect of nitrogenous fertilizations(no nitrogen application and nitrogen application 120 kg/hm2) and planting modes(check-CK,plastic sheet-mulching-PSM,ridge-furrow tillage-RFT and plastic sheet-mulching on ridge-PSMR) on the source characteristic of winter wheat.The main results showed that nitrogen fertilizations were able to increase the nitrogen content of flag leaf significantly,especially at jointing stage.The effect of planting modes was less than nitrogen fertilizations.The flag leaf nitrogen content of PSMR and PSM were higher than the other two planting modes during the filling stage and maturing stage,especially the effect of PSM was more obvious during the filling stage.The chlorophyll of nierogen application was higher than no nitrogen appliction during the different growth scage.The chlorophyll content of RFT was the highest of all the planting modes,while that of CK was the lowest.The area of green leaf per plant under the condition of nitrogen fertilization was increased by 23.4%,20.7%,15.3% and 8.9% compared with no-nitrogen fertilization.The effect of nitrogen fertilization on the area of green leaf per plant was the largest at the reviving stage.Green leaf areas of PSM,RFT and PSMR were higher than CK significantly,and green leaf area of PSMR was the largest.Nitrogen fertilization could significantly increase photosynthetic rate(Pn) of flag leaf.There was a significant difference of Pn between different planting modes,and Pn of PSMR was the largest.However,there was no significant difference between PSM and PSMR.According to the analysis of correlation between different targets and grain yield,it was important for grain yield to increase the nitrogen content of flag leaf,especially during the terminal growth stage.Therefore it was beneficial to increase the nitrogen content of flag leaf and Pn with applying nitrogen,so as to increase grain yield.PSM and PSMR were the first planting modes according to the result of this research.