Effects of nitrogen fertilizer and planting modes on root characteristic of winter wheat in sub-humid farmland ecological system

Chinese. 为了探讨半湿润农田生态系统施氮和栽培模式对冬小麦根系特征的影响，以冬小麦小偃22为供试品种进行大田试验，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、垄沟栽培和垄播覆膜）对冬小麦根系特征的影响。结果表明，返青期至抽穗期小麦根干质量逐渐增加，至抽穗期达到高峰，此后逐渐下降；覆膜处理小麦根干质量降幅大，未覆膜处理小麦根干质量下降幅度小；从不同生育期看，不同栽培模式下施氮处理根干质量均高于不施氮处理。在返青期，常规栽培和地膜覆盖模式下，小麦单株根条数较多，而进入拔节期，常规栽培和垄沟栽培模式下单株根条数明显增多，到孕穗期，地膜覆盖模式下单株根条数增加幅度大，但进入抽穗期，垄沟栽培模式下单株根条数不断增加，而地膜覆盖和垄播覆膜栽培模式下单株根条数显著降低；不同栽培模式下，施氮处理平均单株根条数高于不施氮处理，施氮为9.8，不施氮为7.7。不同栽培模式之间小麦根冠比的差异达极显著水平（P0.01），其中垄沟栽培模式下根冠比最大，为0.491，地膜覆盖栽培模式下根冠比最低，为0.432；在小麦整个生育期，不施氮处理的根冠比高于施氮处理，两者之间差异达极显著水平（P0.01）。因此，在小麦生产中，选择栽培模式时应该重视氮肥的施用，以达到高产。

English. A field experiment was carried out on the soil located in the south part of loess plateau soil with 632 mm precipitation and Xiaoyan No.22 used as indicating crops to study the effects of nitrogen fertilizer (no nitrogen application and nitrogen application 120 kg/hm2) and planting modes (control-C, plastic sheet-mulching-PSM, ridge-furrow tillage-RFT and plastic sheet-mulching on ridge-PSMR) on root characteristic of winter wheat. The results showed, the root weight was gradually increased from reviving stage to booting stage, it reached maximum at booting stage, then it decreased with growth stages; root weight with nitrogen was higher than root weight without nitrogen used in different growth stages under different planting modes. C and PSM's root quantity per plant were more in reviving stage, C and RFT's root quantity per plant were increased significantly when entering booting stage, in booting stage, root quantity per plant of PSM had a vemarkable increase, while root quantity per plant of RFT increased gradually when entering heading, and root quantity per plant of PSM and PSMR decreased in heading stage; root quantity with nitrogen was higher than no nitrogen used in different planting modes, being 9.8 and 7.7 separately. The ratio of root to ground were significantly different at 0.01 between different planting modes, the ratio of root to ground of RFT was largest, which was 0.491, and PSM's was lowest, which was 0.432; the ratio of root to shoot of nitrogen application was higher than no nitrogen application in the whole growth stages, and there was a remarkable relationship between nitrogen application and no nitrogen application (P0.01). Nitrogen application is a key fact when selecting planting modes in wheat producing.