Research Of The Effect Of Chemical Induction On Tobacco Bacterial Wilt Resistance

Tobacco bacterial wilt is a typical soil-borne disease of tobacco.It has become one of the major diseases of tobacco in tropical,subtropical and temperate region.Tobacco bacterial wilt often occurs with blacleg,which leads to crop failure in some field.After infected tobacco curing,its grade and utilization has declined.Loss in tobacco agricultural production caused by tobacco bacterial wilt has become the focus of entire tobacco industry.So far,there are no studies showing there are ways to effectively control tobacco bacterial wilt.Therefore,the prevention of bacterial wilt is related to the healthy development of China’s tobacco agricultural construction.In this experiment,in order to investigate the mechanism of prevention and treatment of tobacco bacterial wilt,using two laboratory-made agents,A and B,I analyze their impact to tobacco phenylalanine ammonia-lyase(PAL)and polyphenol oxidase(PPO)activity in vivo after applying them to tobacco at different concentration.Meanwhile,by investigating each treatment’s incidence of bacterial wilt,average disease index and control efficiency,I provide the theoretical basis of application of agent A and B in controlling and preventing tobacco bacterial wilt in actual field.Experiments are conducted in the experiment station of University of Science and Technology of China and experiment field of Dongzhi county,Chizhou,Anhui,from April 2013 to May 2015.Laboratory tests are carried out mainly via pot experiment.After treatment of agents A and B at different concentration,I analyze the activity of phenylalanine ammonia-lyase and polyphenol oxidase in the 3rd and 7th day,including tobacco leaves,stem and roots.Field experiments are carried out in Dongzhi and Xuancheng in June 2014 using a combination of foliar spraying and swab cuttings.Results are as follows:(1)Agent A and B can improve PAL and PPO in tobacco plants.After treated with 0.1mmol/L A and B,PAL activity in tobacco leaves increases by a big margin.From the 3rdday to 7thday after treated with A,PAL activity in tobacco leaves has a significant decrease,while it maintains improving in the 7 days after treated with B.PAL activity in tobacco roots also greatly improves after treated with B,and is about3 times compared to that in CK group.Meanwhile,A and B have no effect on PALactivity in tobacco main stem.The two concentration of agent induce no significant difference in PPO activity in tobacco leaves,while agent B has better effect with a higher concentration 0.3mmol/L.PPO activity in tobacco roots also significantly improves after treated with A and B,and treated with A is most ideal which improves by 64.86% compared with CK group.Agent A and B can’t enhance PAL activity in tobacco main stem;(2)Field Test indicates that agent A and B can control and postpone the process of tobacco bacterial wilt,and spraying the agent twice has better effect.It can maintain high control efficiency in mid-June,hence guarantee the harvest of tobacco middle leaves in South Anhui and reduce the loss of tobacco farmers,which is beneficial to the tobacco production in this area.