The Biocontrol Efficacy Of Purpureocillium Lilacinus On Gray Mold Disease Of Vegetables

Gray mold disease is a very important vegetables disease,and its pathogen parasites wide hosts in the world.The disease affects the yield and quality of greenhouse fruits and vegetables not only in the growth period but also in postharvest.Currently,people control gray mold disease by fungicide,but the fungicide easily lead to a series of problem such as environmental population,fungicide residue and fungicide resistance.Biocontrol,as a nearly deveoloped method,has been preferred by experts and scholars because of its non-pollution and low resistance risk.There are few reports that Purpureocillium lilacinus can be used to control gray mold disease.The present study try to explore the antagonistic activity and control efficacy of P.lilacinus strain PL36-1 and strain HK.Results are summarized below:1.After checked the antagonistic activity of P.lilacinus strain PL36-1 and strain HK,we found that strain PL36-1,HK can effectively suppress mycelium growth with more than 70%inhibition rate,and lead to deformity of Botrytis cinerea.In the meantime,fermentation filtrate of P.lilacinus can suppress mycelium growth and conidial germination,and the suppression improved as the concentration increase.In addition,it is the first report that VOCs from P.lilacinus could suppress the mycelial growth of B.cinerea.2.The control potential of P.lilacinus was evaluated on tomato by the methods of detached leaves,pot test,fruit inoculation and seed germination.The results showed that spore suspension and supernatant of P.lilacinus could effectively control gray mold disease,and the prevent effect was better than inhibitory effect.The pot experiment proved that control efficacy of PL36-1 was 67.80%,better than strain HK.The control efficacy on tomato fruit gray mold could reached 70.64%when treated by fermentation broth（contain 2×10⁸spores/m L）after 10 days.We also found that fermentation filtrate of PL36-1 can promote tomato seeds germnination and elongation.3.In order to improve inhibitory effect of metabolite of P.lilacinus,we tried to find optimal carbon and nitrogen source of PL36-1.Results show that the better carbon source were sucrose,lactose,corn starch,and the better nitrogen source were 1 g Na NO₃+2 g Soybean cake powder,1 g Na NO₃+2 g Urea on Czapek basal medium.On potato juice basal medium,the better carbon source and nitrogen source were 20 g sucrose+1 g Na NO₃+2 g Soybean cake powder,and the inhibition activity improved 35.72%compared with in PDB medium.Finally,we considered the optimal carbon and nitrogen source of PL36-1 was 20 g sucrose+1 g Na NO₃+2 g Soybean cake powder（1000 m L）.4.The plastic greenhouse experiment shows that control efficacy of fermentation supernatant of PL36-1 was 47.15%when cultured in optimized medium,higher than fermentation supernatant of PL36-1 cultured in PDB medium treatment and PL36-1spores suspension treatment,but lower than 50%procymidone WP 500 times diluent liquid treatment.After test the growth index of pea,we found that growth index had inreeased in different treatments compared to control,but the growth promoting effect of PL36-1 on pea couldn’t be tested in plastic greenhouse.