Study On The Safety Of Metolachlor On Sorghum And Its Safener

Sorghum has a long history of cultivation in my country and has excellent stress resistance.There are data showing that current chemical weeding is one of the main limiting factors affecting sorghum production.Sorghum is a more sensitive small grain crop.Once the medicine is improperly used,it will The herbicide phytotoxicity occurred,causing serious consequences.Metolachlor has the advantages of low price,broad-spectrum and high efficiency,good control effect on gramineous weeds,and low resistance to pesticides.It is a commonly used amide soil treatment herbicide currently registered in sorghum fields,Some areas use metolachlor soil treatment to control weeds in sorghum fields,but the research on its safety to sorghum has not been reported in Heilongjiang Province,and the technology used in sorghum fields is not yet perfect,so it is prone to phytotoxicity.Herbicide safeners can protect crops from the phytotoxicity of herbicides,thereby increasing the safety of crops and improving the effect of weed control.Dichlormid,benzamide(AD-67),fenclorim,and benoxacor can be used as safeners for amide herbicides.However,there is no report about the research on the safety agent to alleviate the phytotoxicity of metolachlor in sorghum.In this study,13 main sorghum varieties commonly used in Heilongjiang Province were selected.Through field experiments,the sensitivity of the tested varieties to different doses of metolachlor was studied,and the effect of metolachlor on the tested sorghum varieties was determined safety.In order to improve the safety of metolachlor,four safeners of amide herbicides were screened.The safeners selected were used to study the mitigation effect of sorghum phytotoxicity,determine the best safener types an d dosages in sorghum fields,and conduct a preliminary study on its protective mechanism.This study aims to provide a theoretical basis for the safe use of metolachlor in sorghum fields,and has important guiding significance for the production of sorghum in Heilongjiang Province.The main conclusions of this paper are as follows:(1)The sensitivity of 13 sorghum varieties to metolachlor is differentThe 13 tested sorghum varieties showed different sensitivity to metolachlor at different growth stages after seedling.At the recommended field dose of 1350 g ai/ha,according to the difference in plant height,fresh weight and control,at 5 days post-emergence,13 All sorghum varieties are sensitive to metolachlor;At 10 days post-emergence,all 10 sorghum varieties were sensitive to metolachlor,accounting for 76.9% of the total number of varieties.Longza 11,Suiza 7,and Qiza 7 were tolerant;At 15 days post-emergence,8 sorghum varieties were sensitive to metolachlor,accounting for 61.5% of the total number of sorghum varieties,including Longza 11,Longza 17,Longza 21,Suiza 7,and Qiza 7 varieties show tolerance.All cultivars are sensitive to metolachlor at high doses of 1650 g ai/ha and 2700 g ai/ha;according to the difference of single ear grain weight at the recommended field dose of 1350 g ai/ha,the Longza 11,Six varieties of Longza17,Longza 21,Longza 22,Suiza 7,and Qiza 7 showed tolerance and were tolerant varieties,accounting for 46.2% of the total number of varieties;Seven varieties of Nuoliang 2,Longza 19,Longza 18,Longza 24,Longza 10,Longza 25,and Miliang 1 are sensitive and are sensitive.(2)The four safeners tested have different effects on sorghum varieties with different sensitivityThe inhibitory effect of the four safeners on Nuoliang 2(S)is generally higher than that of Suiza 7(N)under the supplied reagent amount;At low doses(0.25,0.5 g/kg),the treatment of benoxacor has a certain promotion effect on Suiza 7(N),and the seed treatment of dichlormid,benzamide(AD-67),fenclorim,and benoxaco has a certain effect on the plant height and fresh weight of Nuoliang 2(S)and Suiza 7(N)had a certain inhibitory effect;At three treatment doses of0.25,0.5,and 1 g/kg,benoxacor is safe for two sorghum varieties with different se nsitivities,so benoxacor can be used as a sorghum seed safener.(3)Benoxacor can effectively alleviate the phytotoxicity of metolachlor on sorghumWhen the treatment dose of benoxacor is 1g/kg,it can alleviate the phytotoxicity of metolachlor,and the mitigation rate of the four different doses of Nuoliang 2(S)metolachlor is between 9.01%and 24.96%;The remission rate of 4 different doses of Suiza 7(N)metolachlor was between12.98% and 28.08%.(4)The difference of the protective effect of benoxacor on sorghum cultivars with different sensitivityThe activities of CAT and POD in sorghum treated with the combined action of benoxacor and metolachlor are higher than those treated with only metolachlor,After being exposed to external stress,the CAT and POD activity changes in the two bodies were basically similar,which was significantly higher than that of the control,indicating that the treatment of chloridone has a protective effect on sorghum and can increase the CAT and POD activities in sorghum.The SOD activity of the sorghum treated with the combined action of benoxacor and metolachlor was higher than that of the treatment with only metolachlor,Suiza 7(N)reacted more obviously after being stressed by the medicament,and the change rate of SOD acti vity in the same time was much higher than that of Nuoliang 2(S).It shows that the treatment of benoxacor has a protective effect on sorghum and can increase the SOD activity in sorghum.The SOD activity of tolerant varieties is higher and the protective effect is more obvious.The MDA content in the sorghum treated with the combined action of benoxacor and metolachlor was lower than the content treated with only metolachlor.The decreasing trend of MDA content of Suiza 7(N)was significantly earlier than that of Nuoliang 2(S),indicating that the tolerant variety Suiza 7(N)can clear MDA in the body faster to avoid damage.Therefore,the addition of benoxacor alleviated the lipid peroxidation reaction of sorghum under the stress of metolachlor,and the protective effect on tolerant varieties was more obvious.