施氮和间作对蚕豆根瘤形成及氮素吸收累积的影响

为探究不同施氮水平下小麦蚕豆间作对蚕豆根瘤形成及氮素吸收累积的影响,明确氮肥施用与豆科作物结瘤固氮、氮素吸收累积和产量的关系,通过2年田间试验,分析了N0、N1、N2和N3 4个施氮水平（蚕豆：0、45、90、135kg/hm²;小麦：0、90、180、270kg/hm²）下,单作、间作蚕豆各关键生育期根瘤鲜重、氮素吸收关键参数、地上部氮素累积量和产量的特征。结果表明,N0、N1和N2水平下,间作蚕豆根瘤鲜重比单作分别提高40.9%、27.2%和34.1%;高氮（N3）水平下,单作、间作蚕豆根瘤鲜重无显著差异。与单作相比,4个施氮水平下间作蚕豆的最大氮素累积量（A）和最大氮素吸收速率（R_max）降幅分别为8.01%~13.93%和10.27%~12.98%,表明氮素吸收累积特点与根瘤鲜重相反。在蚕豆营养生长阶段（出苗后90d内）,单作、间作蚕豆氮素累积量无差异;进入结荚期后（出苗90d后）,间作显著降低了蚕豆的氮素累积量。同时,蚕豆产量也受施氮量和种植模式的调控,与单作相比,4个施氮水平下,间作降低蚕豆产量平均达20.66%。整体而言,在N1水平下,蚕豆根瘤鲜重和产量达最大值,随着施氮量增加,蚕豆根瘤鲜重、氮素累积量和产量均随之降低,间作促进根瘤形成的优势减弱甚至消失。因此,间作体系中蚕豆氮肥的运筹与间作优势的形成密切相关。

Effects of Nitrogen Application and Intercropping on Nodule Formation and Nitrogen Uptake and Accumulation in Faba Bean

In order to explore the effects of wheat and faba bean intercropping on faba bean nodulation, nitrogen (N) uptake and accumulation, and faba bean yield under different N levels. Four N levels, 0 (N0, control), 45 (N1), 90 (N2), and 135kg/ha (N3) for faba bean; and 0 (N0, control), 90 (N1), 180 (N2), and 270kg/ha (N3) for wheat. The characteristics of the root nodules weight, nitrogen uptake parameters, aboveground nitrogen accumulation and yield of mono-cropped faba bean (MF) and intercropping faba bean (IF) were analyzed. The results showed that under N0, N1, N2 level, root nodules fresh weight of IF were increased by 40.9%, 27.2%, 34.1%, respectively compared to MF. Under N3 level, root nodules fresh weight of MF and IF were not significant. The maximum N accumulation (A), the maximum N uptake rate (R_max) of IF was decreased by 8.01%-13.93% and 10.27%-12.98%, respectively compared to MF, indicating that the cumulative characteristics of nitrogen absorption were contrary to nodule weight. No difference in N accumulation between IF and MF during the faba bean vegetative growth stages (0-90days after faba bean emerged) under four N levels, but N accumulation of IF was decreased during reproductive growth stages (>90 days after faba bean emerged) compared to MF. Compared with MF, the average yield of IF faba bean was decreased 20.66%. Overall, under N1 level, root nodules fresh weight and yield reached the maximum value, which showed a downward trend with the increase of nitrogen fertilizer application. Therefore, the transportation of IF faba bean nitrogen fertilizer is closely related to the formation of intercropping advantages.