乙草胺胁迫下蚯蚓活动对土壤-作物系统影响研究

Effects of acetochlor stress on soil-crop system in the presence of Eisenia foetida

随着乙草胺的大量使用,其在土壤中的残留量不断增加,严重危害了土壤动物正常生存,蚯蚓尤其如此。蚯蚓对土壤环境质量和作物生长具有明显的改善和促进作用,而乙草胺通过危害土壤动物可能影响作物的产量。为了验证该假设,本研究建立了土壤-蚯蚓-玉米人工控制系统,探讨乙草胺对该系统蚯蚓生理和行为、土壤理化性质及作物生长的影响。研究表明:随着处理浓度的增加,蚯蚓体内SOD呈下降趋势,而MDA呈上升趋势,且于第25 d呈显著正相关;随着处理时间的延长,蚯蚓表现出从表层(0~10 cm)向深处(10~30 cm)迁移的趋势;蚯蚓分层的行为影响了土壤质量,造成深层土壤有机质和碱解氮含量逐渐上升,表层下降;乙草胺胁迫下土壤营养条件下降,玉米株高随着乙草胺浓度的增加而下降。该研究证实,乙草胺除了通过降低地表杂草生存能力、促进作物生长外,还能通过影响土壤动物的生理和行为最终抑制作物的生长,本研究成果可为乙草胺污染对土壤生态系统的生态风险性评估提供数据支撑。

With the extensive use of acetochlor,its residual in the soil is increasing,which seriously jeopardized the normal survival of soil animals,especially earthworms.Earthworms are critically important in regulating soil quality and thus plant growth.Therefore,by mediating the growth of earthworms,acetochlor may have significant negative effects on plant growth which has not yet been well studied.In order to verify this hypothesis,this study established a soil-earthworm-corn system to investigate the effects of acetochlor on physiological and behavioral characteristics of earthworms,soil physical and chemical properties and crop growth.The results showed that:1)With the increase of acetochlor concentration,SOD decreased,while MDA showed an upward trend(significant difference on 25 th day)for earthworm individuals;2)With increasing processing time,earthworm showed a tendency to distribute from the surface layer(0~10 cm)to the depth layer(10~30 cm);3)Variation in earthworm distribution pattern further affected soil quality,resulting in increasing soil organic matter and alkali nitrogen in deep soil layer but decreasing of these two variables in top soil layer.4)Due to decreases in soil nutrition,the plant height decreased with the increase of acetochlor concentration.The study confirmed that in addition to reducing the viability of surface weeds and promoting crop growth,pesticides can also inhibit the growth of crops by affecting the physiology and behavior of soil animals.The results of this study can provide data support for ecological risk assessment of acetochlor pollution on soil ecosystem.