ABSTRACT
ObjectiveTo investigate the effects of exogenous Fusarium oxysporum and Trichoderma viride on the diversity of soil fungal community and carbon metabolic function of cultivated Panax ginseng. MethodIllumina HiSeq 2500 high-throughput sequencing combined with Biolog-ECO was used to analyze the species diversity and functional diversity of soil fungal communities in P. ginseng soil under different exogenous treatments. ResultThe results of high-throughput sequencing showed that the number and species of microorganisms in the soil were significantly changed after exogenous microorganisms were added. The soil fungi with relative abundance greater than 1% included Mortierella sp.，Fusarium sp.，Humicola sp.，and Simplicillium sp. Mortierella sp. in each treatment group significantly increased. Humicola sp. and Simplicillium sp. could be induced to increase by exogenous addition of F. oxysporum，while T. viride at a high concentration could significantly inhibit the growth of F. oxysporum. As revealed by Biolog and principal component analysis （PCA），the average well color development （AWCD） in the high-dose T. viride group （MG） was significantly higher than that in the control group （QS）and the low-dose F. oxysporum group（LD）. The utilization abilities for amino acids，carboxylic acids，polymers， and amines were enhanced in the MG group，but the microbial metabolic activity was reduced in the high-dose F. oxysporum group （LG）. There was no significant increase in the utilization of phenolic acids by soil microorganisms in both groups. ConclusionExogenous addition of F. oxysporum can lead to the growth and reproduction of other pathogenic fungi. Exogenous addition of T. viride can enhance the soil fungal community structure and metabolic diversity，inhibit the proliferation of F. oxysporum，and improve the soil microbial environment of cultivated P. ginseng.
ABSTRACT
Using the field sampling and indoor soil cultivation methods, the dynamic of ginseng rhizosphere soil microbial activity and biomass with three cultivated ages was studied to provide a theory basis for illustrating mechanism of continuous cropping obstacles of ginseng. The results showed that ginseng rhizosphere soil microbial activity and biomass accumulation were inhibited observably by growing time. The soil respiration, soil cellulose decomposition and soil nitrification of ginseng rhizosphere soil microorganism were inhibited significantly (P <0.05), in contrast to the control soil uncultivated ginseng (R0). And the inhibition was gradual augmentation with the number of growing years. The soil microbial activity of 3a ginseng soil (R3) was the lowest, and its activity of soil respiration, soil cellulose decomposition, soil ammonification and soil nitrification was lower than that in R0 with 56.31%, 86.71% and 90. 53% , respectively. The soil ammonification of ginseng rhizosphere soil microbial was significantly promoted compared with R0. The promotion was improved during the early growing time, while the promotion was decreased with the number of growing years. The soil ammonification of R1, R2 and R3 were lower than that in R0 with 32.43%, 80.54% and 66.64% separately. The SMB-C and SMB-N in ginseng rhizosphere soil had a decreased tendency with the number of growing years. The SMB-C difference among 3 cultivated ages was significant, while the SMB-N was not. The SMB of R3 was the lowest. Compared with R0, the SMB-C and the SMB-N were significantly reduced 77.30% and 69.36%. It was considered by integrated analysis that the leading factor of continuous cropping obstacle in ginseng was the changes of the rhizosphere soil microbial species, number and activity as well as the micro-ecological imbalance of rhizosphere soil caused by the accumulation of ginseng rhizosphere secretions.