effect of intercropping system and piriformospora indica fungus on biodegradation of petroleum hydrocarbons under drought and salinity stress in a pb and cd contaminated soil

Background: this research was conducted to evaluate the effect of piriformospora indica (p.indica), drought, and soil salinity stress on diesel oil biodegradation in a soil that was polluted with pb and cd.methods: treatments consisted of corn inoculated with p.indica and white clover intercropping system under the salinity (3.1 and 6 ds/m) and drought (normal and intensive) stress which cultivated in the pb and cd polluted (naturally) soil which simultaneously contaminated with diesel oil at the rates of 0 and 4 % (w/w). after 10 weeks, plants were harvested and the diesel oil biodegradation in the soil was determined. in addition, the soil microbial activity, the apx and pox enzyme activates were measured.results: diesel oil biodegradation significantly increased in the soil under cultivation of plants inoculated with p.indica, while it significantly decreased under salinity and drought stress by 12.9 and 9.8%. however, the intercropping system had positive effects on increasing the soil microbial activity and biodegradation of diesel oil in the soil.conclusion: corn inoculation with p.indica significantly affected the biodegradation of diesel oil in the heavy metals and petroleum hydrocarbon polluted soil that is under salinity and drought stress.