前期研究发现，印度梨形孢（Piriformospora indica)与油菜拌种可以有效缓解乙草胺药害。为进一步研究其作用机制，采用菌丝生长速率法、菌丝悬浮培养法测定乙草胺对印度梨形孢生长的影响，并用气相色谱质谱联用法（GC-MS）检测印度梨形孢菌液、施用印度梨形孢的土壤以及使用印度梨形孢拌种的油菜植株中乙草胺的残留动态。结果表明，当培养基中乙草胺质量浓度为200 mg/L时，其对固体培养基中印度梨形孢生长速率的相对抑制率为98.12%，对悬浮培养液中印度梨形孢鲜质量和干质量的相对抑制率分别为95.11%和96.40%。当乙草胺质量浓度分别为20、50、100 mg/L时，在不添加印度梨形孢的悬浮培养液中，乙草胺的半衰期均为115.52 d，添加印度梨形孢菌饼后，乙草胺的半衰期缩短至9 d以下；每千克土壤添加2 g印度梨形孢菌丝后，土壤中50、100、200 mg/kg乙草胺的半衰期分别为10.35、11.18、11.55 d，均低于未添加印度梨形孢处理的半衰期（11.18、11.95、12.38 d）；同样，采用印度梨形孢拌种的油菜植株中乙草胺的半衰期均短于未进行拌种的处理。综上，内生真菌印度梨形孢的生长受乙草胺影响而减缓，但其自身也可降解培养基中的乙草胺，并能加速土壤及油菜植株中乙草胺的代谢。

In order to explore the mechanism of Piriformospora indica to alleviate the phytotoxicity of acetochlor on rape, this article used the mycelium growth rate method and the mycelium suspension culture method to determine the effect of acetochlor on the growth of P.indica,and gas chromatographic mass spectrometry(GC-MS) was also used to detect the residual dynamics of acetochlor in P.indica,the soil to which P.indica was applied,and the rapes that were seed-dressed with P.indica.The results showed that when the mass concentration of acetochlor in the culture medium was 200 mg/L,its relative inhibition rate on the growth rate of P.indica in solid medium was 98.12%,the relative inhibition rates on fresh and dry quality were 95.11% and 96.40% respectively.When the mass concentration of acetochlor was 20,50,100 mg/L,in the suspension culture medium without adding P.indica,the half-life of acetochlor was 115.52 d,after adding different amounts of P.indica cake,the half-life of acetochlor was shortened to less than 9 days.After adding 2 g of P.indica per kg of soil,the half-lives of 50,100 and 200 mg/kg acetochlor in the soil were 10.35,11.18,and 11.55 d,respectively,all lower than the half-life of the treatment without adding P.indica(11.18,11.95,12.38 d).Similarly,the half-life of acetochlor in rape with P.indica was shorter than that in the control group.In summary,the growth of the endophytic fungus P.indica is slowed down by acetochlor,but it can also degrade acetochlor in the medium and accelerate the metabolism of acetochlor in soil and rapes.