虾稻共作对稻田土壤线虫群落结构的影响

农业生态系统利用种间互惠将种植业与养殖业相结合,既能提高农作物产量,也能减少化肥农药等对环境的危害。本研究以土壤线虫作为指示生物,研究外来物种克氏原螯虾与水稻种养结合模式对稻田土壤生态系统的影响,为虾稻共作模式下稻田生态系统的健康和可持续利用提供依据。通过比较水稻单作和虾稻共作,分别在水稻分蘖期、抽穗期和成熟期采集土壤样品,分析土壤线虫群落结构。结果表明:与水稻单作相比,虾稻共作土壤中食细菌线虫的百分比较高(分蘖期增加了26.52%,抽穗期增加了19.85%,成熟期增加了32.65%),同时机会主义cp1线虫类群所占百分比较高(分蘖期增加了31.13%,抽穗期增加了24.91%,成熟期增加了19.49%),说明虾稻共作生态系统中农田土壤养分循环较快,土壤呈养分富集。但是,虾稻共作农田土壤中捕食杂食性线虫、cp3~5线虫类群百分比较低(P0.05),同时成熟度指数也显著低于水稻单作。因此,在克氏原螯虾的影响下,稻田土壤食物网趋于简化,土壤的生物稳定性有下降趋势,故需要进一步加强虾稻共作对稻田土壤健康长期影响的监测和研究。

Effects of Rice-crayfish Co-culture on Nematode Communities in Rice Paddy Soil

Manipulating crop production and aquaculture in agro-ecosystems by utilizing the positive species interactions can not only increase the yield of crops, but also reduce the utilization of chemical fertilizers and pesticides. In this study, soil nematodes were used as a biological indicator to investigate the effects of co-culture of rice (Oryza sativa) and an exotic species Procambarus clarkii, aiming to evaluating the effect of rice-crayfish co-culture on soil health of agro-ecosystem. Soil samples were collected from rice monoculture and rice-crayfish co-culture at the tillering stage, heading stage and maturing stage of rice and the community structure of soil nematodes were investigated. The results showed that compared with rice monoculture, the percentage of bacterial-feeding nematodes increased by 26.52%, 19.85% and 32.65%, while the percentage of cp1 nematodes increased by 31.13%, 24.91% and 19.49% at the tillering, heading and maturing stages under rice-crayfish co-culture, respectively, indicating a faster nutrient cycling and higher nutrient level in rice-crayfish co-culture ecosystem. However, the percentage of cp3-5 nematodes and the maturity index were significantly lower in rice-crayfish co-culture than those in rice monoculture (P<0.05), indicating that the P. clarkii in co-culture may induce a simplified soil food web and a decreased soil biological stability, thus, further study is needed to monitor soil health in rice-crayfish co-culture ecosystem.