Salicylic Acid Induces Resistance In Phoebe Against Colletotrichum Gloeosporioides

Phoebe anthracnose is a disease caused by Colletotrichum gloeosporioides,which mainly infects leaves and twigs,seriously affecting the growth and development,causing major economic losses.Treatment of two-year-old Nanmu plants with Salicylic Acid(SA),Methyl Jasmonate(MeJA),Validamycin(VAL)and Benzodiadiazole(BTH).Screening for the optimal inducer SA and studying the resistance of SA.Laboratory experiment to determine the inhibitory effect of SA on the growth of pathogenic bacteria,and outdoor determination of soluble protein,superoxide dismutase(SOD),catalase(CAT),peroxidase(POD)in leaves after SA induction.Choose different chemical fungicides for indoor virulence determination on pathogenic bacteria,the best effect is prochloraz,combined with SA to field forest control.The research results provided an important basis for the green control of anthrax.Mainly achieved the following results:1.The best inducing resistance among salicylic acid,methyl jasmonate,Jinggangmycin and benzothiadiazole is salicylic acid,and its induction effect is 64.69%,which is significantly higher than other Inducer induction effect.The optimal induction effect of methyl jasmonate was 51.21%,and the optimal induction effect of benzothiadiazole was 26.33%.The induction effect of jingtanmycin was the worst,and the optimal induction effect was only 15.85%.2.The effects of SA at concentrations of 0,50,100,200,500 mg·L-1 on mycelial growth and spore germination of pathogens were determined,and the inhibition of lesions by in vitro inoculation of leaves treated with SA.The results showed that low concentration of SA had no significant inhibitory effect on mycelial growth rate and spore germination,and the inhibitory effect was significant when the concentration reached 500 mg·L-1.The plants were treated with the above five concentrations of SA spray,and the leaves were collected for in vitro inoculation with anthrax.The results showed that:Different concentrations of SA treatment can inhibit the growth of pathogenic bacteria.When the concentration of SA was 100 mg·L-1,the inhibition rate of lesions was the highest,reaching 64.28%.The inoculated leaves were observed by scanning electron microscopy to show that the conidia of the pathogen could germinate normally,but the growth of the germ tube was inhibited,and the deformation or swelling of the stem was observed.3.The plants with the above concentration of SA were sprayed,and the relevant physiological indexes of the leaves were collected at 5 days,and the sterile water was used as a control.The results showed that the leaf-related physiological indexes induced by SA of 100 mg·L-1 were significantly higher than other concentrations and sterile water control.The protein concentration was 2.11 times that of the control,the CAT activity was 2.03 times that of the control,the POD activity was 1.3 times that of the control,and the SOD activity was 1.10 times that of the control.Therefore,the SA of 100 mg·L-1 is the optimal induction concentration.After treatment with 100 mg·L-1 of SA,the pathogens were inoculated and the physiological indicators were measured.Sprayed with sterile water and not vaccinated as a control.the result shows:The soluble protein,SOD,CAT and POD of the leaves increased over a period of time.At the peak,the soluble protein was 2.57 times that of sterile water sprayed and not vaccinated.The SOD activity was 1.21 times that of the control,the CAT activity was 2.04 times that of the control,and the POD activity was 1.46 times that of the control.After that,it showed a downward trend.Under the condition of no inoculation after SA treatment,the physiological activity of the plants was significantly higher than that of the control.Therefore,SA can induce the resistance of phoebe to anthracnose.4.The indoor virulence test was carried out with different fungicides,and the EC50 were prochloraz(0.130 mg·L-1),carbendazim(0.497 mg ·L-1)and tebuconazole(0.577 mg·L-1,Difenoconazole(1.145 mg·L-1),Tridemorpholine(39.811 mg·L-1).The combination of prochloraz and SA for field.The results showed that the combination of prochloraz with SA and rosin diene had the lowest disease index and the best control effect,which was 59.01%.