The Ability Of Trichoderma To Control Hanfu Apple Trees Rot Disease And Promote Trees Growth

Hanfu apple is fruit tree variety with high economic value in Liaoning province.It has excellent characteristics such as cold resistance and high yield,but it suffers from apple rot disease.At present,chemical methods are generally used to control apple rot disease,but this is likely to cause harm to humans and the environment.Trichodema spp.are environmentally friendly,green and healthy high-efficiency biological control fungus with broad-spectrum and high-efficiency resistance for a variety of plant diseases.In order to find out the Trichoderma strains that can control the rot disease of Hanfu apple trees,Trichoderma of 13 plants rhizosphere soil in Xinjiang wild fruit forest were isolated and identified in this experiment.And the control effects of different Trichoderma on the rot disease of Hanfu apple trees and the growth promotion effects on Hanfu apple seedlings were studied.In this experiment,a total of 122 Trichoderma strains were isolated from the rhizosphere soil samples of 13 plant species.Through morphological and molecular identification,89strains of T.asperellum,21 strains of T.harzianum and 12 strains of T.atroviride were finally identified.Among them,T.asperellum were distributed in all soil samples and had the largest number,which was the dominant species.The T.asperellum NECC21257,Tas257,T.harzianum NECC21253,Tha253 and T.atroviride NECC21247,Tat247 were screened according to characteristics such as growth rate and spore production for subsequent experiments.The 3 strains of Trichoderma were fermented by laboratory patented method,and it was found that the spore production of Tat247 was low.Therefore,the solid-state fermentation formula of the Tat247 strain was optimized,and the spore production was 1.0×10⁸spores/g when the ratio of rice husk to wheat bran was 90:10 and the content of（NH₄）₂SO₄was0.5%.And this spore production could meet the needs of the experiment.Both Trichoderma and fermentation filtrate had inhibitory effects on Cytospora mail C1（Cma）.The 3 strains of Trichoderma hyphae could wrap Cma hyphae.The inhibition rate of Tas257 fermentation filtrate against Cma could reach 85.41%at 4 d,and the mycelia would expand,deform or even rupture.Trichoderma had good control effects on Hanfu apple trees rot disease.The prevention and treatment experiments were carried out on isolated branches and apple seedings by applying 3 Trichoderma spore suspensions alone and combination（Tcom）.The prevention effects of isolated branches and apple seedings were 41.88%and 73.14%,respectively treatment with Tas257 and the treatment effects were 38.05%and 28.39%,respectively.The results showed that the prevention effects of Trichoderma was higher than that of treatment effects.The POD and PPO activities were increased by 3.12 times（Tas257+Cma）and 2.64 times（Tha253+Cma）,respectively and the MDA content was decreased by 21.85 mmol/g（Tcom+Cma）after Trichoderma treatment.In addition,the expression levels of PR1 and PR4 reached the highest levels in Tcom+Cma treatment at 3 d,which were 1243.34 and 296.11 times,respectively.So different Trichoderma strains may improve the abilities of Hanfu apple trees to against rot disease by increasing the antioxidant capacity and inducing the expression of defense response genes.Trichoderma spore suspension could promote the growth of Hanfu apple seedlings.The soil phosphatase activity after Tcom treatment was 1.22 times that of the control and leaves dry weight and specific leaves areas were 1.42 and 1.29 times,respectively.The dry weight and fresh weight of roots after Tat247 treatment were 1.82 and 2.03 times that of the control,respectively,and the growth of lateral branches were 1.93 times（10 d）and 1.88 times（30 d）respectively.And after Trichoderma treatment,the chlorophyll content decreased,which could promote the growth of new leaves.In addition,Trichoderma hyphae could colonize roots after Tha253 and Tcom treatment by electron microscopy.In conclusion,different Trichoderma could promote the growth of Hanfu apple seedlings.In brief,the Trichoderma isolated from the wild fruit forest in Xinjiang has good biocontrol effects on Hanfu apple trees rot disease and good growth promotion effects on Hanfu apple seedings.At the same time,the Trichoderma strains with good biocontrol effects screened in this experiment can provide strain resources for the biocontrol of Hanfu apple rot disease.