| Rape sclerotinia rot is an important disease threat of rape production. The pathogen of rape sclerotinia rot is Sclerotinia sclerotiorum (Lib.) de Bary. It has characters such as heavy damage, strong stress resistance and difficult to control. According to the domestic and foreign researches, inducing plant to improve disease resistance by inducer, as a new effective disease prevention way, has achieved certain success in various interaction system of plants and disease. At present, the inducing effect of inducer on rape sclerotinia rot is still of lack of research. Therefore, this paper studied on the induced resistance of nine inducers such as BTH, TDL, C-22, ZHS-1, ZHH-4, BABA, SZG-7, C-13and ZHS-2. In order to provide evidence for the prevention of rape sclerotinia rot, we do some further studies on the SZG-7and BABA’s physiological mechanism of sclerotinia sclerotiorum induced-resistance. The main results are as follows.1. The screening and effect of rape sclerotinia rot inducerIn the tested concentration range of the nine inducers used in the experiment, five kinds, C-22, ZHS-1, ZHH-4, C-13and ZHS-2, couldn’t induce disease resistance of rape seedlings. And only four kinds, BTH, TDL, BABA and SZG-7could induce the rape seedling’s resistance of rape sclerotinia rot. The lesion area of inhibitory rate is7.84%-43.98%. Induced-resistance strength is followed by SZG-7>BABA>BTH> TDL.100mg/LSZG-7has best induced-resistance effect, and the relative inhibitory rate of it is43.98%; the10mg/LBTH has lowest induced resistance effect and the rate was only7.84%. In the tested concentration range, TDL’s induced-resistant effect will enhance with the increase of concentration, and the induced-resistant effect of SZG-7, BABA and BTH will first increase and then decrease increased with increasing concentrations. However, the induced-resistance of the four will weaken with the prolonging of treatment time.In order to inspect BTH, TDL, BABA and SZG-7are fungicides or not determine their resistance effect is the induction mechanism or the sterilization mechanism, we do in vitro antibacterial test. The results show that the mycelia’s growth rate, color and diffusion of the four on the PDA panel are identical with the control. It explains that the four in the concentration range do not inhibit direct effects on Sclerotinia sclerotiorum mycelium, which can effectively inhibit the lesion expansion because of inducing the self-resistance of rape.Different induced-resistance methods lead to different effect. It is measured the relative inhibition rate of lesion area with100mg/L SZG-7and100mg/L BABA after spraying, injection method and irrigation method, and results show that spray method gains the highest rate, and injection method gains the lowest. Plant after induction treatment needs a certain time interval to be exhibited induced-resistance. This study is effort to find out the best induction interval time and duration of inducer. The experiment shows that the best induction time interval of100mg/L SZG-7is three days and the duration of it is up to fifteen days. The best induction time interval of100mg/L BABA is four days, and duration of it is at least fifteen days. Induced-resistance can be divided into the local resistance and the resistance of the systemic acquired resistance. In this study both SZG-7and BABA was the systemic acquired resistance, but the local resistance treatment is stronger than the resistance of the untreated parts. Increase the times of induction treatment under the condition of the certain concentrations and treatment interval could enhance the induced-resistance.2. Study on physiological mechanism of induced-resistanceMechanism of plant induced-resistance has many aspects including histopathological mechanism, physiological and biochemical mechanism and molecular biology. This study mainly measures enzyme activity’s changing and the content of resistance index of MDA. The results are as follow. First, all SOD, POD, CAT, PPO, PAL, β-1,3-glucanase activity shows a rising trend with only inoculation and only induction and induction-inoculation treatment, and even higher than that of control. The related enzyme activity increase rapidly after inoculation treatment, slower after induction-inoculation treatment and the slowest after induced treatment. However, from the point view of activity’s rising range, induction-inoculation is the largest and inoculation is the smallest, with the extension of time related enzyme activity gradually decreased. Second, the content of MDA increases at first and then is equal to that of comparison after inoculation treatment, after induction-inoculation or induction treatment it decreases first and then remains constantly with the extension of time. Consistent with All these physiological changes consistent with SZG-7and BABA’s induced-resistance effect of rape Sclerotinia sclerotiorum. It seems that these physiological changes are the physiological mechanism of SZG-7and BABA induced rape sclerotinia sclerotiorum.3. Field testThis study measures the field induced-resistance effect of100mg/L SZG-7, which is the best in lab. Result shows that induced-resistance effects of100mg/LSZG-7reached62.23%, next only to the concentration of50%carbendazim’s79.91%. As a result, SZG-7has development potential to be resistance inducers of rape Sclerotinia sclerotiorum. |
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