| Biocontrol agents are thought as promising and environmental friendly approaches as agrochemicals, for phytodiseases have caused serious environmental and health problems. Trichoderma species have been widely used in suppression of soil-borne pathogens. In this paper, we report the two endophytic fungi Trichoderma koningiopsis YIM PH30002 and Trichoderma gamsii YIM PH30019, which isolated from the root of 2-years old healthy Sanqi(Panax notoginseng F H Chen), and their antagonistic activity against phytopathogens associated with the host plant. The influence of 11 agrochemicals commonly used in Panax notoginseng cultivation was also detected, based on the growth of two Trichoderma species, and get the conclusion as following:(1) Trichoderma koningiopsis YIM PH30002 can not cause pathogenicity on Panax notoginseng seedlings, and exhibited significant inhibition of the growth of four host root-rot phytopathogens, by covering the colony of phytopathogens, coiling and twisting the mycelium in the mechanism of mycoparasitism, producing volatile organic compounds(VOCs). Identified by GC-MS, T. koningiopsis produced at least10 kinds of volatile substances on PDB culture medium, classed as alkanes,monoterpenes and arenes, heterocycles, aldehydes.(2) Trichoderma gamsii YIM PH30019 was non-pathogenic to the host,presented appreciable biocontrol efficacy, and could tolerate chemical fertilizer concentration up to 20 %. T. gamsii YIM PH30019 displayed antagonistic activities against the pathogenic fungi of P. notoginseng via production of volatile organic compounds(VOCs). On the basis of GC-MS, VOCs were identified as dimethyl disulfide, dibenzofuran, methanethiol, ketones etc., which are effective ingredients for antagonistic activity. T. gamsii YIM PH30019 could protect P. notoginseng plants from soil-borne disease in the continuous cropping field tests.(3) Under the condition of penetration, 11 agrochemicals can inhibit the growth of T. gamsii and T. koningiopsis in different degree, wherein three kinds of fungicides including No. 3 Jialiu·Fumeishuang, No. 5 Yijunniao and No. 6 Fumeili, and threekinds of insecticides including No. 9 Shapulin, No. 10 Yanleguo and No. 11 Gaolv Ma, strongly inhibited two Trichoderma spp.. Only No. 8 insecticides Jiaanji Aweijunsu Benjiasuanyan can gently impact the colony morphology and growth rate of two Trichoderma spp., the other 10 kinds of pesticides showed different degrees of inhibition. Results of liquid fermentation showed that five kinds of insecticides had the less influence on mycelia dry weight of two Trichoderma spp., than that of six kinds of fungicides. Both the results of liquid culture and biomass in soil indicate that T. koningiopsis present a better agrochemicals tolerance than T. gamsii. In potting soil environment, No. 3 fungicide Jialiu·Fumeishuang showed inhibition on biomass of two Trichoderma spp. in different degree, while No. 9 insecticide Shapulin could help T. gamsii improve the biomass. |
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