Herbicides On Soil Microbial Activity And P450 Degradation Behavior Of Herbicides

Influence of Chloroacetanilide herbicides pretilachlor , butachlor, acetochlor and metoalchlor on soil catalase and polyphenol oxidase activities was investigated at concentration of 0.1 .10.50. 100|4g. g-1 respectively. Results show that herbicides have different effects on this two soil enzymes, they have stronger effect on catalase than on polyphenol oxidase, particularly for pretilachlor; the higher concentration of herbicides the more effect to land enzyme. So we can use catalase as index enzyme, to explore and judge the effect of pesticide to soil ecological environment.The effects of these four Chloroacetanilide herbicides to soil respiration were also studied in this paper. Results show that soil respiration had high sensitivity to four Chloroacetanilide herbicides. At the beginning of apply, soil respiration was inhibited by the herbicides strongly, inhibition degree is 22.0%~35.2%. The soil respiration can recover gradually, and also show some stimulation effect, and they have no apparent effect after 34 days. Judging by soil respiration, we can conclude that Chloroacetanilide herbicides are low toxicity or no actual harm-ness pesticide, in other words that they are almost harmless to soil microorganism.Cytochrome P450 was extracted from rice, and metabolic kinetics of cytochrome P450 to butachlor, metoalchlor and their enantiomers are studied. The results show that cytochrome P450 can degrade butachlor, metoalchlor and their enantiomers rapidly, the degradation half-life-time between 14.68 to 150.52min. The degradation rate lower as the pesticide concentration higher (20ug ml"1, 30ug ml"1 and 40ug ml"1), the corresponding half-life-time longer. The degradation rate of these herbicides followed the order: butachlor> metoalchlor> metoalchlor S-isomer.