Soil Microbial Mechanisms Underlying Growth Promotion of Flue-cured Tobacco by Enhanced Application of Pseudomonas Bio-Organic Fertilizer

To elucidate the soil microbial mechanisms underlying the growth promotion of flue-cured tobacco by Pseudomonas-enriched bio-organic fertilizer, three treatments were established: conventional fertilization (CK), traditional organic fertilizer (OF), and Pseudomonas-biofertilizer (BF). These were evaluated for effects on leaf dry mass per plant, rhizospheric soil nutrients, microbial community structure, and relative abundance of pathogenic fungi. The results demonstrated that BF significantly increased leaf dry mass by 0.98% and 12.1% compared to OF and CK, respectively. Compared to CK, BF significantly increased cured tobacco yield value, soil available N, P, K, DOC, and microbial co-occurrence network stability, while significantly decreasing the relative abundance of pathogenic fungi. Random forest analysis identified DOC, average clustering coefficient, average path length, and pathogenic fungal abundance as key determinants of leaf dry mass. Notably, leaf dry mass showed a highly significant positive correlation with DOC content and the clustering coefficient of microbial co-occurrence networks, while exhibiting negative correlations with average path length and the relative abundance of pathogenic fungi. In conclusion, Pseudomonas-biofertilizer optimizes rhizospheric nutrient availability and microbial network architecture, suppresses pathogenic fungi, and promotes tobacco growth, demonstrating superior application potential over traditional organic fertilizers.