Studies On Screening And Mechanism Of Botanical Safeners Of Paddy Herbicide Acetochlor

Acetochlor is a highly active, broad-spectrum pre-mergence chloroacetanilide herbicide selective corn that controls many annual grasses and certain broadleaved weeds when soil-applied . Acetochlor has very high activity in rice field. Recently, acetochlor is successfully used for the control of weeds in transplanted rice field. But,because rice is extremely sensitive to acetochlor, acetochlor is induced to rice seedling injury easily, which is limited to acetochlor used in rice seriously. So,It is very important for agricultural production to study on safeners of paddy herbicide acetochlor. Safeners can protect crop plants from herbicides injury without reducing activity in target weed species. Botanical safeners are different with chemical safeners, it comes from plants, which can harmony with environment, it don't result in new pressure to environment. On the base of former studies, the activity of alcohol extracts from 48 plant species were tested as herbicide safeners that protect rice from acetochlor injury by means of bioassay in laboratory.The main results is listed as followed:1. The extracts from plant A or B have detoxified effect on acetochlor in 48 plant species, which can protect 3-days rice seedling from acetochlor (0.05mg/L) injury. The detoxified effect of 0.125g/L plant A extraction and 0.25g/L plant B extraction on acetochlor is the highest in different concentrations of plant extractions. The antidoted activity of plant extractions from A or B is not same under different concentrations of acetochlor. When the concentration of acetochlor is not more than O.lmg/L, The rice seedling grows well because of the protection of extracts from plant A and B, rice heightx fresh weight have no obviously differential between the treatments and the controls. The protective effect of extracts from plant A or B on rice is lessen with the rise of the concentration of acetochlor; On the condition of 0.8mg/L acetochlor, extracts from plant A and B don't protect rice from acetochlor injury.2.The protective effect of extracts from plant A or B on different rice varieties is not obviously different. Degree of injury to the rice varieties(xiangzaoxian29 > baliangyou96, xingxiangyouSO > weiyou46) is different by acetochlor , But rice seedings treated with extracts from plant A or B (the concentration of the former is 0.125g L-1 ,the latter's is 0.25g L-1) did suffer few damage from acetochlor , rice height and fresh weight at four rice varieties are basically restored to the control 's.3. After rice seedlings were treated with acetochlor plus plant extractions from A or B, the content of glutathione(GSH) and the activity of glutathione-S-transferases (GST) are improved in leafs. That results showed that a plausible mechanism of extracts from plant A or B saferning activity would be stimulated the activities of glutathione-s-transferases(GST) and improved the content of glutathione(GSH), which catalyse the conjugation of acetochlor with glutathione. Therefore, they may protect rice from acetochlor injury. Further laboratory and field studies are needed to verify the mechanism of safening action.