长期不同施肥方式对稻田杂草群落的影响

Effect of long-term fertilization pattern on weed community diversity in rice field

利用太湖地区农业科学研究所31年的长期肥料定位试验田,分别于2011—2012年水稻抽穗期、结实期和收获期进行了杂草群落调查,并对杂草种群分布与土壤养分因子进行冗余分析。结果表明:随着水稻的生育进程,田间杂草密度增大,而氮磷肥的配施也能有效减少试验区田间杂草的密度;牛毛毡、鸭舌草、耳叶水苋和水蕨是水稻生长期的主要杂草类型;在施入磷肥的处理中,莎草科杂草密度减少甚至消失,鸭舌草密度则增加,耳叶水苋和水蕨则是在没有施肥的处理生长最好;氮磷配施减少群落丰富度的同时能增加群落的均匀度,人为干预相对最少的处理方式有利于群落结构的稳定发展。抽穗期RDA结果显示,第1、第2排序轴特征值分别为0.901和0.080,土壤全P、有效磷、全氮、碱解氮与第1排序轴相关系数分别为-0.887、-0.816、-0.810和-0.794。太湖地区稻麦两熟制条件下,长期不同施肥方式显著影响稻田杂草的群落组成,土壤养分库的差异性影响田面杂草密度和优势种群分布,影响稻田中杂草分布的土壤养分因子主要为氮、磷和有机质,土壤钾含量对杂草的总体分布影响相对较小。

Fertilization can alter the natural succession process of the weed community in cropland by directly improving the yield and competitive advantage of crops and changing the nutrient content and structure of the soil. We investigated the weed community diversity in rice field in a rice-wheat rotation system during 2011- 2012 after a 31-year long-term application of different fertilizers in Taihu Lake,and analyzed the effects of soil nutrients and fertilization on weed distribution. Fertilizer treatments included： CK（no fertilizer）,N（N fertilizer）,NP（N plus P fertilizer）,NK（N plus P fertilizer）,PK（ P plus K fertilizer） and NPK（ N plus P and K fertilizers）. The redundancy analysis（RDA） was performed to examine the relationship between fertilizer management and weeds. Among the weeds,Eleocharis yokoscensis,Monochoriav aginalis,Ammannia arenara,and Ceratopteris thalictroides were the dominant species. The long-term application of nitrogen and phosphorus fertilizers could significantly reduce the density of weeds.Phosphorus fertilizer applications significantly reduced the density of sedge and effectively increased the density of M. aginalis,while A. arenara and C. thalictroides grew best in no fertilizer treatment. The application of nitrogen and phosphorus fertilizers could reduce the richness index and increase the evenness index of weed community. In no application of fertilization（CK）,the biodiversity of the cropland ecosystem was maintained at a high level,indicating the no-fertilizer treatment was adequate to meet the growing needs of most of the weeds. At the heading stage of rice,the eigenvalues of the first and second ordination axes were 0. 901 and 0. 080,respectively. The coefficients of correlation between the soil total P,Olsen P,total N,available N and the first ordination axis were- 0. 887,- 0. 816,- 0. 810,and- 0. 794,respectively. Soil organic matter,nitrogen and phosphorus contents were the main environmental factors affecting the distribution of weeds. The results also indicated that the application of different fertilizers affected the community composition of the weeds.