Early identification of phytotoxicity symptoms and risk control of ethoxysulfuron on tobacco
[Aims]The sulfonylurea herbicide ethoxysulfuron is widely used in tobacco-rice rotation areas in China.Correctly identifying the symptoms of ethoxysulfuron damage,clarifying the causes and thresholds of phytotoxicity,can help ensure the safety of tobacco production.[Methods]The field trials and indoor pot tests were used to study the phytotoxicity symptoms of tobacco caused by ethoxysulfuron residue.[Results]The results of field trials indicated that the residue of ethoxysulfuron could lead to yellowing and wrinkling of tobacco leaves,resulting in stunted tobacco plants.In severe cases,it could lead to tobacco withering and death.The pot test results showed that there was a dose-effect relationship between ethoxysulfuron residue and tobacco phytotoxicity.With the increase of the exposure dose of ethoxysulfuron,its inhibitory effect on the height and leaf area of tobacco gradually enhanced.On day 30 after application of ethoxysulfuron at 30 μg/kg,the inhibition rate on the height and leaf area of tobacco was more than 10％.In the high-dose treatment group of ethoxysulfuron,the content of chlorophyll and indoleacetic acid(IAA)in tobacco leaves significantly reduced,while the content of abscisic acid(ABA)significantly increased,which might be the main reason for tobacco plant dwarfism and yellowing.Additionally,ethoxysulfuron exposure caused changes in proline content,superoxide dismutase(SOD)activity and malondialdehyde(MDA)content in tobaccos,suggesting that ethoxysulfuron induced stress resistance and antioxidant effects in tobacco plants.The residual dissipation of ethoxysulfuron in field soil followed the first-order kinetic equation,with a half-life of 16.5 d.[Conclusions]Based on the dissipation characteristic and damage threshold,the preharvest interval of ethoxysulfuron on tobacco was estimated to be 69 d.This study can provide assistance for the correct use of ethoxysulfuron in tobacco-rice rotation area and ensure the safety of tobacco production.
NETL
NSTL
万方数据
维普
