Study On The Effects Of Corn Herbicides Drift On Tobacco

In maize-tobacco intercropping area of China,it is a common phenomenon that corn and tobacco are grown in adjacent fields of the same season.The large use of herbicides in corn fields often causes serious damage to tobacco.In recent years,due to the lack of relevant research reports,the phytotoxic caused by the drift of spraying herbicide in corn fields is becoming a major problem in tobacco production.Therefore,seven kinds of corn herbicides were tested in the seedlings of five main flue-cured tobacco varieties.First,we determined the degree of phytotoxicity of corn field herbicides to tobacco,and then identified the resistance levels of 35 tobacco germplasms to cornfield herbicides,and by measuring changes in the content of Malondialdehyde(MDA)and Glutathione(GSH)in tobacco,analyzed the mitigation effects of the alleviator on the phytotoxicity.The results provide a theoretical basis for guiding the scientific and rational use of corn herbicides in the corn-tobacco intercropping area,which has practical application value for tobacco safety production.1.Phytotoxicity of herbicide application in corn fields on intercropped flue-cured tobaccoSeedlings of five main flue-cured tobacco varieties were used as experimental materials in the seven corn herbicides test.The results showed that a certain dose of seven corn herbicides had certain effects on the growth and development of tobacco plants,but the degree of damage was significantly different(P<0.05).2,4-D butyl ester and fluroxypyr in seven herbicides caused more serious phytotoxicity,although they were diluted 150-fold,most of the tobacco seedlings sprayed with them still showed obvious symptoms.The phytotoxicity of MCPA-Na(2-methyl-4-chlorophenoxy acetic acid)was second to 2,4-D butyl ester and fluroxypyr.And the degrees of phytotoxicity caused by tribenuron-methyl and mesotrione were at intermediate levels.Both Atrazine and clodinafop-propargyl caused smaller phytotoxicity.The experimental results also showed that Yunyan87 and Zhongyan100 varieties had lower level tolerance to 6 kinds of herbicides.Both NC55 and K326 varieties had higher tolerance to most tested herbicides.Therefore,both atrazine and clodinafop-propargyl are preferable choices for corn fields in tobacco production area.Mesotrione and tribenuron-methyl are the next choices.Both 2,4-D butyl ester and fluroxypyr are not suitable for used.MCPA-Na should be used cautiously.2.Tolerance identification of different tobacco germplasm to herbicides in corn fieldIn order to identify tolerance of tobacco germplasm to common corn herbicides clodinafop-propargyl and atrazine,35 tobacco germplasms were tested in greenhouse.According to variety tolerance response ancestry,35 tobacco germplasms can be divided into four types: the highly tolerant,the moderately tolerant,the moderately sensitive and the highly sensitive.The results showed that among the 35 germplasms,the higher tolerance to clodinafop-propargyl contained 9 varieties,with 26% of all germplasm materials;moderately tolerant germplasms,moderate sensitive germplasms and highly sensitive germplasms were 11 varieties(31%),9 varieties(26%)and 6 varieties(17%),respectively.And there were 14 varieties with the highly tolerant germplasms to atrazine,and 8(23%),5(14%)and 8 varieties(23%)with the moderately tolerant,the moderately sensitive and the highly sensitive,respectively.Based on analysis on tolerance of different germplasms,damage leaf ratio,damage index and relative damage index were significant different(P<0.05)among tolerance types.3.Changes of MDA and GSH content relief effects in flue-cured tobacco under corn herbicide stressThe relief effects of six antidotes on the herbicide phytotoxicity in corn field were studied by measuring the changes of MDA and GSH content in tobacco.After the occurrence of phytotoxicity,the use of antidotes can alleviate the phytotoxicity symptoms of tobacco,reduce the content of MDA,but increase the content of GSH,thereby alleviating the phytotoxicity of herbicides.For clodinafop-propargyl phytotoxicity,the use of brassinolide and gibberellic acid can reduce the effect by 60%,the MDA content can be reduced by about 30%,and GSH content increased to 80% of the blank control.There is no strict requirement for spraying time.For the treatment of atrazine,the use of Zhiliyuan and brassinolide before application was the most effective in improving the toxicity of atrazine,the relief effect was over 60%,the MDA content was lower than the blank control,and the GSH content was also significant.According to the comprehensive analysis,there are some differences in the degree of relief of clodinafop-propargyl and atrazine by the 6 antidotes.The relief effects of antidotes used before application is better than that after the phytotoxicity.This also has guiding significance for solving the problem of herbicide drifting damage in maize-tobacco intercropping fields.