| In recent years, herbicides were applied widely. Concerns have been raised about effect on non-target after application with herbicides. Peanut is one of important crops for food and oil plant in our country. With application of chemical weeding in peanut, the disease of peanut arosed by Sclerotium rolfii Sacc.was more and more aggravated. The purpose of this paper is to study effect of herbicides on Sclerotium rolfii of peanut. In this study, 9 herbicides (acifluorfen, oxyfluorfen, oxadiazon, lactofen, clomazone, metolachlor, trifuralin, pendimethalin, acetochlor) were determined on S.rolfii in vitro such as the growth rate, dry weight of the mycelium, pathogenicity, the capacity of producing sclerotia, the fresh weight per sclerotium and germination of per sclerotium in laboratory; In greenhouse, the pathogenicity of scleraotium and peanut after treatment with 9 herbicides was studied; At last, effect mechanism of herbicides on S. rolfii of peanut was studied. The results could be summaried as follows:1.The studies of 9 herbicides on S. rolfii in vitro showed that the toxicity of 9 herbicides to S. rolfii was different. Acifluorfen and oxyfluorfen were more toxicity than other herbicides, LC50 was 7.88 mg. L-1 and 18.91 mg.L-1 respectively.2. The mycelial dry weight was inhibited by all herbicides except acetochlor (25mg.L-1). Acifluorfen and oxyfluorfen (100 mg. L-1, 50 mg. L-1) had reached more than 90% respectively. All tested herbicides except acetochlor and metolachlor had inhibited sclerotium products of S. rolfii. The inhibition of acifluorfen was more than 96% in all tested dose.Acetochlor and trifuralin had reduced per sclerotium dry weight and others had enhanced. The per sclerotium dry weight of acifluorfen was 8.34 fold compared with control. All the tested herbicides had no effect on sclerotium germination.3. The results of 9 herbicides on peanut showed that both disease percent and disease index were lower than inoculated control after inoculated with treatment by oxyfluorfen, trifuralin, oxadiazon, and others could enhance them. Acifluorfen and acetochlor were the worst in all treatments, the disease index were3.05 and 4.39 fold repectively compared with control.4. The results of inoculated the sclerotium after treatment with 9 herbicides showed that after inoculating the sclerotium by oxyfluorfen and clomazone (lOOmg.L"1) treatment, the disease percent was lower than inoculated control, disease index was only 10.25 and 11.50 hi all dose repectively.And others were higher inoculated control. After treatment with acifluorfen (6.25mg.L"', 12.5mg.L~1), oxadiazon (lOOmg.1/1), acetochlor (200mg.L"1, 400mg.L~I) and metolachlor (400 mg.L"1), the disease index was more than 80%.5. The primary investingations on the physical and biochemical mechanism that after treatment with 9 herbicides, they lead to the different dynamic changes POD, CAT, PPO, PAL activities and soluble protein content in peanut.5.1 All soil-applied herbicides except oxyfluorfen, oxadiazon and pendimetha -lin the same as control could increasee POD activity. At 3d treatment with oxyfluorfen and oxadiazon, POD activity were 17.64 and 7.032 fold repectively compared with control; After 17 days, the activity of treatment by two herbicides were 2.98 and 5.32 fold repectively compared with control at the second highy, But POD activity changed was 14.61fold at 10 days by trifuralin.At 8d treatment with lactofen and oxyfluorfen, POD activity is higher than acifluorfen and control in all post emergence herbicides.5.2 All herbicides could affect PPO activity. In all soil-applied herbicides, the PPO activities were 1.78 and 1.88 fold compared with control after treatment with oxyfluorfen and trifuralin at 17d and 24d repectively. The PPO activity went up at 12d of treatment with lactofen and went down after. It's activity was 1.6 fold compared with control.5.3 All herbicides have little affect on PAL activity. But different herbicides have different changing on PAL activity. The PAL activity of treatment with pendi... |
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