Study On The Control Mechanism Of White Clover Disease And The Effect On Plant Growth By Trichoderma Longibrachiatum

White clover is an excellent lawn ornamental plant.The leaf disease of white clover seriously affected the ornamental value and garden scenery.Trichoderma Longibrachiatum SMF2,SMF2)and its antimicrobial peptide Trichokonins(TKs)have biological control effects on a variety of plant pathogens.In this paper,the effects of Trichoderma Longibrachiatum SMF2 and TKs on the growth of white clover and the control mechanism of leaf spot were studied,which provided a theoretical basis for better use of Trichoderma spp.to control Landscape plants diseases.The main conclusions are as follows:1.Three pathogens of white clover leaf diseases were isolated and identified.The pathogens were identified by morphology combined with molecular biology.The results showed that the three pathogens were Alternaria arborescens,Alternaria tenuissima and Alternaria alternata.2.Trichoderma Longibrachiatum SMF2 and TKs have the control effect on white clover leaf disease.(1)The results of plate confrontation test showed that SMF2 had a certain inhibitory effect on the growth of three pathogens of white clover leaf diseases,A.arborescens,A.tenuipes and A.alternata,and the maximum inhibition rates were 62.59%,51.79% and 54.19%,respectively.The pot experiment of white clover showed that TKs had a good bactericidal and control effect on white clover leaf spot,and could induce white clover to improve the resistance of leaf spot.Spraying and root irrigation methods were used to carry out germicidal control and induction protection experiments.The results showed that TKs had a good control effect on white clover leaf spot in the concentration range of 0.001～100mg/L,and the control effect increased at first and then decreased with the increase of concentration.With the increase of time,the control effect after 14 days treatment was lower than that after 7 days treatment.When A.alternata was treated with TKs with the concentration of 32mg/L,the maximum inhibition rate of mycelial growth was 71.64%,the maximum inhibition rate of spore production was 60.85%,and the OD260 value of mycelium culture medium increased by 25.00%.3.TKs had a significant effect on the growth of white clover.In the range of0.001～100mg/L,TKs promoted the germination and growth of white clover at low concentration,while it inhibited the germination and growth of white clover at high concentration,and the promoting effect was better when the concentration was0.01～1mg/L.Compared with the control,the germination rate,germination energy,germination index and vigor index of white clover seeds increased by 1.42%,2.42%,15.45% and 24.04% respectively,and the underground dry weight,aboveground dry weight,whole plant dry weight and root-shoot ratio increased by 7.51%,16.65%,10.25%and 3.04%,respectively.There was no significant difference in tissue water content.After21 days of treatment with TKs,the plant height,total root length,root projection area,root surface area,total underground volume and total aboveground volume of white clover increased by 44.13%,84.17%,73.53%,73.53%,57.89% and 67.21%,respectively.The average root diameter was the highest when the concentration of TKs was 100mg/L,which was 58.53% higher than that of the control.The POD activity increased by 201.19%,and the MDA content decreased by 38.87%.