Development and Evaluation of Biocontrol Agents Against Panax ginseng Root Rot / 中国实验方剂学杂志

ABSTRACT

ObjectiveTo develop safe and effective microbial agents against Panax ginseng root rot. MethodP. notoginseng endophytes were screened in plate confrontation tests， followed by morphological and molecular biological identification of antagonistic strains， optimization of strain fermentation conditions in a single factor test， and determination of optimal carriers and auxiliary agents of the microbial agent and their ratio using response surface methodology for formulating the production process. The prevention and control effects of the microbial agent were verified in the confrontation and pot culture experiments. ResultThe plate confrontation test yielded a strain named Fusarium pseudoanthophilum with significant resistance to root rot， and its antibacterial rate was 53.33%. According to the single factor test， the fermentation conditions of F. pseudoanthophilum were determined to be fermentation time 60 h， fermentation temperature 26 ℃， speed 120 r·min-1， and pH 6.5. The response surface optimization results showed that the number of viable bacteria reached the maximum （5.23×109 cfu·g-1） when the peat was 60.00 g， sodium carboxymethylcellulose 3.50 g， and sodium alginate 4.76 g. The influences of carriers and auxiliary agents on the number of viable bacteria were sorted by degree in a descending order as follows： peat>sodium carboxymethylcellulose >sodium alginate. The confrontation test results showed that when the microbial agent concentration was greater than 1.00 g·L-1， it had a significant inhibitory effect on the root rot pathogen F. oxysporum and the inhibitory rate was more than 42.3%. As demonstrated by the pot culture experiment， the inoculation of biocontrol agent for 28 d significantly reduced the incidence （66.99%） of root rot in P. ginseng seedlings and disease index （61.69%） and increased their leaf length （33.04%） and fresh weight （34.48%）. ConclusionF. pseudoanthophilum inoculant is efficient in preventing and controlling the root rot， making it worthy of further development and utilization.