土壤线虫群落对过量施用农用化学品的响应

Response of soil nematode community to excessive application of agrochemicals

为研究施用过量的农用化学品对土壤线虫群落组成及多样性的影响,采用定点试验的方法,在哈尔滨市呼兰区选择典型农田生态系统进行试验,对比研究土壤线虫群落对施用过量的氮肥、磷肥、钾肥、除草剂及杀虫剂的响应。在试验田中共鉴定出土壤线虫27科45属,其中Cephalobus和Aphelenchus为优势属。施用不同浓度的各类农用化学品对土壤线虫群落组成、多样性均产生一定影响。线虫总数及食细菌线虫、食真菌线虫、植物寄生线虫数量在不同处理间均存在显著差异(P<0.05);其中,植物寄生线虫的相对丰度随化肥施用量的升高呈增加趋势。从土壤线虫的生态指数来看,除PPI(植物寄生线虫成熟指数)外,其他生态指数[MI(成熟度指数)、F/B(食真菌线虫与食细菌线虫数量比值)、Evenness(均匀度指数)、SR(丰富度指数)、H'(多样性指数)]在施用不同农用化学品处理之间也存在显著差异,并且,MI随着施用钾肥、氮肥浓度的增加而降低。土壤线虫可以作为揭示施用农用化学品过程中土壤质量变化的生物学指标,其群落及多样性的变化表明土壤线虫群落对农用化学品的过量施用产生了响应,过量施用农用化学品会增加土壤生态系统的干扰,对土壤环境造成威胁。

oil nematodes are the most abundant group of soil animals.Nematodes rapidly react to environmental changes.In the farmland ecosystem,any factor that affects the soil environment（tillage,fertilizer,pesticide and herbicide measures） influences the composition and diversity of soil nematode community.The response of soil nematode community to excessive application of agrochemicals was investigated in a typical farmland ecosystem in the Hulan area of Harbin in this study.The study used excessive amounts of nitrogen,phosphate and potassium fertilizers along with herbicides and pesticides in soil,and investigated nematode communities and community diversity.A total of 27 families and 45 genera were observed in the study.Cephalobus and Aphelenchus were the most dominant genera.The composition of soil nematode community,relative abundance of different trophic groups and diversities were influenced by different agrochemical treatments.Significant differences were noted among different treatments in terms of the number of total soil nematodes,and bacterial-feeding,fungal-feeding and plant parasites nematodes（P 0.05）.With increasing quantity of applied chemical fertilizers,the relative abundance of plant parasitic nematodes increased.Except for PPI（plant parasitic index）,soil nematode community responded differently to the different treatments in terms of the ecological indices of MI（maturity index）,F/B（number ratio of fungal-feeding nematode to bacterial-feeding nematode）,Evenness（evenness index）,SR（richness index） and H＇（diversity index）.Also MI declined with increasing quantity of applied nitrogen and potassium fertilizers.The variations in soil nematode communities and diversities suggested that the response of soil nematode communities to agrochemicals was a suitable bio-indicator that adequately reflected the effects of agrochemicals application on soil quality.The excessive application of agrochemicals increased the level of disturbance of soil ecosystem and posed a significant threat to soil environment.This study was important in guiding future research on agricultural production and providing the theoretical basis for the sustainable development of agriculture and ecological systems.