Effect of Enhanced Organic Material Addition during Reductive Soil Disinfestation on Disease Resistance, Yield Increase, and Microbial Community in Flue-Cured Tobacco

Abstract

The addition of organic materials is pivotal for the efficacy of reductive soil disinfestation (RSD). However, data on the influence of varying amounts of organic matter during RSD on soil-borne disease mitigation, yield increase, and rhizosphere microecological health in the current flue-cured tobacco season remain limited. This study analyzed various organic material addition rates (CK, G0.8, G1.0, and G1.2) at two experimental sites (K and Y). The results indicated that increasing the application of organic material improved the soil physicochemical properties (pH, AN, AP, AK, OM, and C/N), mitigated the severity of black shank and Fusarium root rot, and amplified the tobacco yield. The K/YG1.2 treatment significantly reduced the Shannon and Sobs fungal indices across both sites, and enhanced the relative abundance of the bacteria Actinobacteria, Chloroflexi, Firmicutes, and Acidobacteriota, while decreasing the relative abundance of Ascomycota. The bacterial genera were predominantly represented by Sphingomonas and Bacillus, whereas the fungal genera were represented by Saitozyma, Mortierella, and Fusarium. The addition of organic materials during RSD substantially decreased the relative abundance of Mortierella and Fusarium. Using FUNGGuild and Tax4Fun to evaluate the application of adding organic matter during the RSD process, we identified that rhizosphere fungi in high application rates of flue-cured tobacco were primarily saprophytic or pathogenic saprophytes, which were mainly involved in the metabolism, environmental information processing, genetic information processing, and cellular processes. The results of the two experimental sites indicate that applying 15 t·ha−1 (K/YG1.2) of solid residues such as vegetables during RSD emerges as the optimal choice. This strategy is highly effective in guaranteeing the sterilization and pest control effect of the RSD process, facilitating the reconstruction of microbial community diversity, lowering pathogen abundance, managing soil-borne diseases that are prevalent in the current flue-cured tobacco season, and leading to an increase in tobacco yield.