Study On The Inhibition Mechanism Of Atrazine On Soybean And The Dissipation Of Atrazine Degradation Products

The changes of soybean growth amount,chlorophyll content,antioxidant enzyme activity and malondialdehyde?MDA?content under atrazine residue stress in corn-soybean rotation system were studied.The results showed that when atrazine was used in the previous crop?corn?at different concentrations,there was no significant difference in the germination and emergence of soybean in the later crop in each group,but there were significant differences in the chlorophyll synthesis and antioxidant enzyme activity in soybean leaves in each group.The use of high concentration atrazine in the previous crop would cause oxidative damage and inhibit the later growth of soybean.When atrazine was used for 1000g/ha in the previous crop,the chlorophyll content in soybean leaves was 66.4%?80%of that in the control group?no atrazine was used in the previous crop?within 15d-35d.When the amount of atrazine used in the previous crop was 250g/ha,500g/ha and 1000g/ha,the antioxidant enzyme activity in soybean leaves was enhanced and the activity of ascorbic acid peroxidase was more sensitive than other oxidases.With the addition of 1000g/ha,the ascorbic acid peroxidase activity in soybean leaves was significantly different from other groups.The activity of peroxidase and superoxide dismutase reached its peak at15d,and catalase reached its maximum at 35d.The soybean has a certain tolerance to atrazine.The normal dosage of the previous crop?250g/ha?will not produce toxic effect on the subsequent crop of soybean,while the multi-dose of the previous crop?1000g/ha?will produce significant toxic effect on the latter crop of soybean.The effects of soil temperature,soil moisture and application concentration on the dissipation of atrazine degradation products,deethylatrazine?DEA?and deisopropylatrazine?DIA?,in soils were studied by laboratory simulation.The results showed that temperature had a significant effect on the dissipation of DEA and DIA in soils.When the soil temperature increased from 15?to 35?,the half-life of DEA decreased by 1.1 d?Fluvo-aquci soil?,8.1 d?Black soil?and the dissipation rate increased by 27.8%?Fluvo-aquci soil?,21.1%?Black soil?in 21 days.The half-life of DIA decreased by 1.8 d?Fluvo-aquci soil?,4.1 d?Black soil?,and the dissipation rate increased by 20.4%?Fluvo-aquci soil?and 21.2%?Black?in 21 days.DEA and DIA in Fluvo-aquci soil showed the same law with different soil moistures.DEA and DIA in Black soil showed the opposite rule of the dissipation with different soil moistures,and the dissipation of DEA slowed down with the increase of soil moisture,while the dissipation of DIA became slower with the increase of soil moisture.When the application concentration increased from 0.1 mg·kg^-1to 0.5 mg·kg^-1,the half-life of DEA and DIA in Black soil and Fluvo-aquci soil decreased significantly.While the application concentration increased to 1 mg/kg,the dissipation rate of DEA and DIA in the two soils decreased and the half-life became longer.The half-lives of DEA and DIA in Black soil were longer than those in Fluvo-aquci soil,but they degraded more thoroughly in Black soil.The results would provide preliminary data for the environmental safety assessment of DEA and DIA and their dissipation in soils.