Studies On Screening Resistance Inducers For Tobacco To Bacterial Wilt And Protective Enzyme

Tobacco bacterial wilt is one of main diseases of tobacco in South China. The induced disedses resistance of plant is one of the measures to effectively utilice resistance resources in plant, so it has great value of application and practice significance to plant disease contol.Tobacco was inoculated with bacterial wilt after sprayed of series of concentrations of inducers and put in light incubators with a temperature of29～31℃, humidity of90%～95%and illumination of16hours. Result showed that the concentration of200mg/L of chitosan(CTS) performed the most notable induced resistance and the result was81.17%. When the concentration was25mg/L, induced resistance of CTS was also reached47.92%; Methyl Jasmonate(MJ) also showed obvious induced resistance. When the concentration was200mg/L, the induction effect was75.46%after5days’ vaccination and54.30%after7days’ vaccination.2,6-dichloroisonicotinic acid(INA) and salicylic acid(SA) didn’t had long persistence. The induced resistances were76.64%,74.22%after5days’ vaccination and27.29%、25.06%after7days’ vaccination. Azadirachtin and thiabendazole(TBZ) showed low induction effect to tobacco bacterial wilt and with a result of25.65%,23.82%after7days’ vaccination when the the concentration was200mg/L. As a commercialization inducer, the induction effect of BTH was only53.15%after5days’ vaccination when the concentration was200mg/L. The disease index reached80.64after7days’vaccination and almost no induced resistance when the concentration was25mg/L.Effect of using both inducer and streptomycin showed that it had no obvious function to both chitosan and MJ. INA and SA were the same with chitosan and MJ in3day’s vaccination, but they showed antagonistic effect on the5th and7th day. However, BTH promoted remarkably synergistic effect with a efficiency coefficient above100.Colorimetry was used to determine the enzyme activity of peroxidase (POD)、 superoxide dismutase (SOD) and polyphenoloxidase (PPO) of tobacco. Through determination, Result showed that chitosan also had the most obvious improvement enzyme activity. The raise of activity of POD、SOD、PPO was respectively24.05%、41.22%、181.85%and Methyl Jasmonate(MJ) take second place.