不同有机类肥料对小麦和水稻根际土壤线虫的影响

Effects of different organic fertilizers on soil nematodes in the rhizosphere of rice and wheat cropland

国内外对土壤线虫的研究绝大部分都是基于旱地的非根际土壤,对水田土壤,尤其是水旱轮作下根际土壤线虫对有机肥的响应研究非常地有限。因此,探讨在稻麦轮作体系中以猪粪堆肥和秸秆为原料的不同有机类肥料,对水稻和小麦根际土壤线虫的影响。田间试验处理为:CK(不施肥)、F(100%化肥)、PF(猪粪堆肥+50%化肥)、SF(秸秆全量还田+100%化肥)、PSF(猪粪堆肥+秸秆全量还田+50%化肥)、PMF(猪粪商品有机无机复合肥)。结果表明:小麦根际主要线虫优势属为头叶属(Cephalobus)、拟丽突属(Acrobeloides)和丝尾垫刃属(Filenchus);水稻根际则为杆咽属(Rhabdolaimus)、潜根属(Hirschmanniella)和丝尾垫刃属(Filenchus)。小麦根际土壤线虫总数显著高于水稻根际;SF和PSF对两季土壤线虫总数的提高显著高于PF和PMF,F对线虫总数没有显著影响。线虫营养类群表现为小麦根际食真菌线虫相对丰度显著高于水稻根际,植食性线虫和杂食/捕食性线虫丰度显著低于水稻根际。有机肥对稻季线虫群落的影响远大于麦季,秸秆配施有机肥显著提高麦季瓦斯乐斯卡指数(WI);施肥均显著提高稻季的多样性指数(H'),降低优势度指数(λ)。土壤线虫对肥料的响应取决于作物及肥料的质量和养分含量;在稻麦轮作系统下,同时添加秸秆和猪粪对提高土壤线虫数量和食微线虫丰度更有益。

With rapid global nutrient enrichment,the responses of soil biota to nutrient addition have gained much attention. There are numerous studies addressing the responses of soil nematodes and microorganisms to chemical or organic fertilization. Moreover,existing studies of nematode communities mostly focused on uplands as well as on bulk soil. As yet,the responses of soil nematodes in the rhizosphere to both chemical and organic fertilization remain unclear. This is of special significance for the widespread rice-wheat rotation agro-ecosystem in China,where chemical fertilization is commonly used and organic fertilization is promoted,e.g. straw return. The aim of our study was to assess the effects of both chemical and organic fertilization on soil nematodes in the rhizosphere of rice-wheat rotation agro-ecosystems in eastern China. We applied fertilization treatments（ CK： no fertilizer,F： 100% chemical fertilizer,PF： pig manure compost ＋ 50% chemicalfertilizer,SF： straw return ＋ 100% chemical fertilizer,PSF： pig manure ＋ straw return ＋ 50% chemical fertilizer,PMF：commercial fertilizer of pig manure mixed with chemical fertilizer） in a factorial experimental design to rice- and wheatcropland in Jintan,Jiangsu Province. We measured soil nematode abundance and diversity,as well as soil nutrients and soil environmental parameters in the rice and wheat rhizospheres. Two-way analysis of variance（ ANOVA） was performed after testing variable normality and homogeneity of variance. Duncan tests were used for post-hoc comparisons. Cephalobus,Acrobeloides and Filenchus were the dominant genera in the wheat-growing season; while Rhabdolaimus,Hirschmanniella and Filenchus dominated in the rice-growing season. Total nematode abundance was significantly higher in the wheat-growing season than rice-growing season; SF and PSF increased the total abundance of nematodes compared to PF and PMF; there was no significant difference between CK and F. For nematode trophic groups,the relative abundance of fungivores was significantly higher in the wheat-growing season than the rice-growing season,while plant-parasites and omnivores / predators tended to be more abundant in the rice-growing season. In terms of individual abundance and diversity,the effects of organic fertilization on the soil nematode community were more pronounced in the rice-growing season than in the wheat-growing season. For example,the straw addition tended to increase the Wasilewska index（ WI）,while both 100% chemical fertilizer and all the combined organic fertilizer treatments increased the Shannon-weaver index（ H＇） but deceased the Dominance index（ λ）. This suggests that the responses of soil nematodes to fertilization depend not only on crop type,but also on fertilizer quality and nutrient content. For example, combined addition of straw and pig manure was most advantageous for improving both nematode abundance and the relative abundance of microbivores in our study system.