Abstract
Meloidogyne incognita causes significant damage to many different crops. Previous studies showed that Streptomyces rubrogriseus HDZ-9-47 is a promising biocontrol agent. Combining it with biofumigation improved its efficacy against M. incognita. In the present study, the reason for the improved efficacy of the combination was investigated by analyzing its impact on both the soil microbial and the nematode communities in the field. The results showed that the combined application reduced root galls by 41% and its control efficacy was greater than each treatment alone. Cultivation-based analyses showed that the combination treatment affected the soil microbial community. Actinomycetes and bacterial densities were negatively correlated with the root knot score. In contrast, the fungal densities were positively correlated with the root knot score. Denaturing gradient gel electrophoresis (DGGE) results showed that the combination of S. rubrogriseus HDZ-9-47 and biofumigation enriched beneficial microbes and reduced certain soil-borne fungal phytopathogens, thereby enhancing the efficacies of both S. rubrogriseus HDZ-9-47 and biofumigation against M. incognita. And HDZ-9-47 could colonize in soil. The total abundance of nematode and plant parasites, the ratio of soil fungivore nematode to fungivore plus bacterivore nematode, and the nematode diversity indices all decreased with the combination treatment. Overall, the results of this study demonstrate that combined application of HDZ-9-47 with biofumigation was a useful and effective approach to suppress M. incognita by manipulating soil microbial communities in field.
Highlights
Meloidogyne incognita is a serious agricultural pest
S. rubrogriseus HDZ-9-47 combined with soil biofumigation improves control efficacy against M. incognita
The combined application of S. rubrogriseus HDZ-9-47 and biofumigation had superior efficacy against M. incognita compared with either treatment alone[9]
Summary
Meloidogyne incognita is a serious agricultural pest. It attacks a wide range of crops and causes dramatic yield losses[1]. M. incognita was controlled mainly with chemical nematicides Most of these products have been banned because of their toxicity to soil ecosystems and human health. Li et al reported that combining soil biofumigation with antagonistic Pseudomonas reinekei SN21 was highly effective against M. incognita in the field[8]. Soil microbes and nematodes usually play important roles in agro-ecosystems They influence soil nutrient cycling, organic matter formation and decomposition, soil structure, and plant systemic resistance. Analyzing the effects of combined application of biocontrol agents with biofumigation on the soil microbial and the nematode communities is helpful for understanding the mechanism of improved performance in field. Before deploying the combination of biocontrol agents and biofumigation on a large scale, it is necessary to assess their impact on soil microbial communities
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