低浓度除草剂对植物及土壤线虫群落的影响

Effects of low-concentration herbicides on the diversity and community composition of plant and soil nematodes in fallow land

农业生态系统中低浓度除草剂的生态风险值得关注。本研究选取中国北方休耕地为研究样地,采用大田随机区组设计,喷施低于大田推荐剂量的莠去津或苯磺隆以模拟飘散的低浓度除草剂,处理30 d后对比各样地中植物和土壤线虫群落特征。结果表明:大田推荐剂量及低于大田推荐剂量的莠去津(1 200、600、300 g·hm^(-2),以有效成分计)或苯磺隆(22.5、11.25、5.63 g·hm^(-2),以有效成分计)处理样地中,相对于空白样地植物群落物种组成改变,植物群落多样性指数和丰富度指数显著降低,均匀度指数无显著变化。1 200、600、300 g·hm^(-2)(以有效成分计)的莠去津或22.5、11.25、5.63 g·hm^(-2)(以有效成分计)的苯磺隆处理样地中,相对于空白样地土壤线虫群落组成和稀有属组成改变,稀有属数量减少,而线虫群落多样性指数、生活史多样性指数和营养类群多样性指数无显著变化。低于大田推荐剂量的两种除草剂对于植物群落的影响大于大田推荐剂量除草剂的影响,同样增加土壤环境胁迫压力。实际生产中,从农田飘散出的低浓度除草剂对周边半自然生境中生物多样性的影响值得防控。

The ecological risks of low concentrations of herbicides in agroecosystems are worthy of attention. In this study, fallow land in northern China was selected as the study sample, and the field random block design was adopted to compare the community characteristics of plant and soil nematodes after the spraying of atrazine at 1 200, 600, and 300 g·hm-2(active components)or tribenuron-methyl at 22.5,11.25, and 5.63 g · hm-2(active components)for 30 d. The results showed that the different doses of atrazine and tribenuron-methyl changed the species composition of plant communities and significantly reduced the diversity and richness indices of plant communities but did not significantly change the evenness index of plant communities in the fallow land. Compared with the blank control, the different doses of atrazine and tribenuron-methyl changed the soil nematode community composition and the rare genera, as well as reduced the number of rare genera present. However, it did not significantly change the community, life history, or nutrient group diversity indices of the soil nematodes. There were no significant differences in the effects of atrazine or tribenuron-methyl with less than the recommended field application concentration and the recommended field application concentration on the plant communities. Different concentrations of herbicides increased soil environmental stress in the fallow land. The results suggest that the ecological risks of low concentrations of herbicides should not be ignored in the development of practical biodiversity conservation strategies in agroecosystems.