冬油菜与杂草对长期不同施肥的差异性适应

研究长期水旱轮作条件下,施肥模式对田间冬油菜、杂草、土壤养分及冬油菜–杂草空间分布的影响,为长江流域冬油菜轻简化生产提供依据。2011年在湖北省粮油主产区——江汉平原布置水稻–冬油菜轮作肥效定位试验。2016年冬油菜收获期,调查农田杂草群落多样性和分析油菜–杂草–土壤养分三者状况。结果表明,长期土壤养分亏缺会显著影响油菜–杂草的生长和空间分布、形成不同的杂草优势群落。平衡施肥(NPK处理)有助于增加冬油菜根茎粗、有效分枝数、角果数和最终产量,降低杂草总生物量,提高杂草群落多样性Shannon-Wiener指数。与NPK处理相比,–N、–P和–K均会不同程度地降低籽粒、茎秆、角壳和杂草的养分吸收量,尤以–P处理降幅最为明显。与土壤养分含量的初始值相比,长期不施用化肥会引起土壤氮磷钾有效含量下降,尤其对于土壤钾,现有平衡施肥措施不足以弥补农田钾素亏缺,应重视秸秆还田的补钾效果。总之,长期科学的农田养分管理与调控措施,不仅可以降低杂草对冬油菜的危害、增强生物多样性和形成良性的油菜-杂草竞争环境,也有利于减少化学药剂使用、推动冬油菜的轻简化生产。

Different Adaptations of Winter Rapes and Weeds Responding to Long-term Balanced Fertilization

In order to provide a scientific basis for simplified cultivation of rapeseed in the Yangtze River Basin, the effects of fertilization models on rapeseed, weeds, soil nutrients, and the environment of the rapeseed crop in a paddy-upland system were studied. A long-term (2011-2016) field experiment was carried out on Jianghan Plain. Through field investigation and lab analysis, data on weed communities and the rapeseed-weed-soil nutrient status were obtained during the rape harvest season of 2016. The results showed that the soil nutrient deficit significantly affected the growth and spatial distribution of both rape and weeds, and could influence the formation of different weed communities. However, balanced fertilization clearly increased the thickness of the rape roots, the branch number, the pod number and the final yield, and also reduced weed biomass and increased the Shannon index. Compared with NPK treatment, separate -N, -P and -K treatments reduced the nutrient uptake of grain, stem, shell and weeds to different degrees, especially for P treatment. Long-term fertilization deficits caused soil N, P and K content to decrease compared to the initial value, especially for K. The existing balanced fertilization measures were not sufficient to make up for the K deficiency, indicating the importance of the straw K resource. Overall, long-term scientific nutrient management and regulation, can not only reduce damage from weeds, strengthen biodiversity and form a favorable competitive environment for the rape, but can also reduce the use of pesticides and promote the simplified cultivation of rapeseed in South China.