Development Of Trichoderma Citrinoviride Biocontrol Manure Against Meloidogyne Incognita

Meloidogyne spp.is an important plant parasitic nematode and has widely concerned by countries around the world for its wide distribution and serious damage.At present,with long-term use of chemical pesticides leading to the emergence of the 3R problems,more and more researchers are turning their attention to biological control.Trichoderma citrinoviride Snef1910 was a high biocontrol efficiency fungus against root-knot nematode from the preliminary screening in our laboratory.In order to make Trichoderma as biological products for controlling root-knot nematode disease,the response surface methodology was used to optimize the fermentation conditions of T.citrinoviride Snef1910.The technological process and dosage of spore powder,and its control effect in the greenhouse were verified in this study.The main results were as follows:1.Response Surface Methodology was used to optimize fermentation conditions of chlamydospore of T.citrinoviride Snef1910.Basal culture medium for chlamydospore of Trichoderma were screened from 10 kinds of media,and the key factors of liquid fermentation affecting the production of chlamydospore were selected by single factor test and Plackett-Burman test.The steepest climbing test and the Box-Behnken response surface method were used to determine the level of key factors which affected the production of chlamydospore.The results showed that the seed culture medium for chlamydospore of T.citrinoviride was wheat bran medium,the best carbon source was sucrose,nitrogen source was peptone,and inorganic salt was KH2PO4.The optimal liquid fermentation conditions were obtained by the response surface method center combination test,that were inoculation amount of 3.62%,liquid content of 29.2%,wheat bran content of 30 g/L,sucrose content of 4.52g/L,peptone content of 2.62g/L,and initial p H of 3.04.The number of chlamydospore in flasks and fermentation tanks was 5.90 × 107/m L and 5.11 × 107/m L,respectively,which was about 12 times higher than that of chlamydospore in the non-optimized wheat bran medium.2.Preparation of Trichoderma spore powder: The eriodic survival rate of the obtained conidia powder and chlamydospore powder were determined at room temperature.With the increase of storage time,the survival rate of spores decreased.The conidia survival rate was 14.55% when stored for 10 months,while the viability of conidia began to decline to one half in the 6 month.But the chlamydospore was about 70% survival rate in the 10 month.The application of 0.3%-0.5% spore powder had a significant control effect on M incognita,and no significant inhibitory effect on plant growth.However the amount of spore powder more than 0.5% inhibited the-tomato growth,and excessively high levels caused plant death.3.Trichoderma biocontrol manures development and control effect : Trichoderma spores powder was mixed with 5 kinds of different organic fertilizers,then screened the biochar and wheat bran fertilizers which enhanced control effect of the spore powder through pot and field experiments.The control effect of the Trichoderma biochar manure on M.incognita was up to 82%,and Trichoderma wheat bran manure reached 67.00%,furthermore the tomato height and aboveground fresh weight were increased significently.The results of field experiments in greenhouse showed that both types of manure could significantly reduce the infection of M.incognita on tomato roots,and the number of ocysts and J2 s in tomato roots and soils in 2018 and 2019.The relative control efficacy of Trichoderma biochar manure was higher than that of wheat bran manure,which was 77.4% and 58.76%,respectively.In addition,the plant height and yield of tomatoes treated with two manures increased significantly,and the yield of tomatoes per mu increased by 6.54% and 7.14%.Two kinds of manure were applied to the muskmelon pot experiments,and the similar results were obtained to that of tomato experiments.Both of them could effectively prevent M.incognita and promote the growth of muskmelon above the ground.The effect of biochar manure treatmented on muskmelon was 77.48%,higher than that of avermectin(60.37%)and wheat bran manure(44.44%).4.Effect of Trichoderma manures on the rhizosphere microbial community of muskmelon was researched.The rhizosphere soil microbes of melon were collected to determine the biodiversity by Biolog-ECO method.Compared with the no treatment muskmelon control(CK),there was no significant difference in the microbial activity,and Shannon,Simpson,Mc Intosh diversity index of soil microbial community treated with two Trichoderma manures.Except for lipids and acids,the ability to use the other four carbon sources of manures was basically the same as CK.Compared with CK and two manures,the microbial diversity,and Shannon,Simpson,and Mc Intosh diversity index of soil microbial community of avermectin-treated melon were significantly decreased in here.Meanwhile,except for amines,the ability to use the other five carbon sources was significantly reduced.We developed the two biocontrol manures of Trichoderma with biochar and wheat bran,the treatments not only inhibited M.incognita infection to tomato and melon significantly,but also had no effection on the activity and diversity of rhizosphere microbes of potted melon.The researches provided a basis data for the large-scale production and application of Trichoderma biocontrol manures.