Slowing Effects Of Biochar On The Stress Of Acetochlor In Maize Seedling Stage

Acetochlor is one of the most used herbicides in China.However,due to the impact of the environment,weather,soil and other factors,improper use will have a serious impact on the environment.The researches show that biochar is one of the new materials for soil remediation with the characteristics of rich carbon,porous nature and large specific surface area,when applied in the soil,it can promote the growth of plants,passivate pesticides and heavy metals in the soil,affecting the bioavailability and migration of pesticides and heavy metals.Therefore,in this paper the effects of acetochlor on the growth of maize seedlings were studied from the aspects of biochar application on the main enzyme activities,chlorophyll and MDA content,and also studied the effect on the residue and half-life of acetochlor in the soil under the addition of biochar,providing technical support and theoretical basis for the reasonable application of acetochlor.The test results are as follows:(1)Acetochlor had a coercive effect on the growth of maize seedlings,and with the increase of concentration,the stress increased.Acetochlor had inhibitory effects on plant height and chlorophyll content;Antioxidant enzymes in the plant are also stressed,three kinds of concentrations treatment at high、medium and low of acetochlor all increased the activity of SOD in young roots and leaves;Compared with the control group,the POD and CAT of the plants in the primary treatment of 100ml/mu were lower and higher in late period;The activity of POD and CAT increased in 200ml/mu treatment;The treatment of 400ml/mu made the SOD and POD of Maize in seedling stage increased first and then decreased,but the activity of CAT was lower than that of CK;The application of acetochlor increased the content of MDA in the plant;With the stress time prolonging,the stress was weakened,but the effect of high concentration acetochlor on the various indexes in the plant was irreversible.(2)The results of biochar mitigation on acetochlor stress showed that:Biochar could effectively alleviate the stress of Acetochlor on plant height,chlorophyll and soluble protein content;The effect of biochar on the recovery of acetochlor on ground and underground parts of maize seedlings has big difference,changes of enzyme activity in root better reflected recovery effect of biochar on acetochlor stress effects;0.5% biochar treatment made the root SOD activity recovered to the control level;In the early stage of acetochlor,the POD had little change,the addition of biochar inhibited the activity of POD,and the activity of POD increased at 21 days after treatment,and the effect of the treatment of acetochlor was the best in the treatment of 1% biochar;Low amount of biochar addition increased CAT activity,high volume of biochar decreased CAT activity;Treatment of 1.0%,2.0% can alleviate stress effects of Acetochlor on the CAT;Added biochar can effectively reduce the content of MDA,the biochar treatment of 0.5% and 2.0% close to the treatment of CK in the roots,but 2.0% of the treatments significantly reduced the MDA content in the young leaves of the plants,so 0.5% biochar treatment was the best.Unde the action of acetochlor stress,biochar made the activity of AMS in maize roots increased first and then decreased,and the change of AMS in young leaves was opposite.Based on the above results,0.5% to 1% of biochar had the best effect on acetochlor stress.(3)In this study,the dynamic changes of acetochlor residues in soil were determined by gas chromatography internal standard curve method.The half-life of acetochlor was calculated by the dynamic equation of pesticide residues.The results showed that: The half-life of acetochlor in the tested soil was 6.93 days,When the amount of biochar was 0.1%,0.5%,1.0%,2.0%,and 3.0%,the half-life of acetochlor was 7.79 d,9.12 d,16.91 d,30.51 d,40.77 d,respectively.The half-life of acetochlor in soil was increased by 0.86 d,2.19 d,9.98 d,24.58 d,33.84 d compared with no biochar added.The results showed that the biochar had a better adsorption on acetochlor,and the half-life of acetochlor was prolonged with the increase of the amount of biochar.