Rhizosphere microbial community stability and phosphorus availability drive phenotypic differences in garlic growth

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Abstract Background The rhizosphere microbiome and soil nutrients are critical for crop growth, but their roles in regulating garlic productivity remain unclear. This study aimed to identify the key factors driving growth differences in adjacent garlic fields under uniform management. Methods Rhizosphere soils from two adjacent plots (H: vigorous growth; L: stunted growth) were analyzed for their physicochemical properties and microbial communities via 16 S rRNA and ITS sequencing, combined with network analysis and redundancy analysis (RDA). Results The results revealed significantly greater available phosphorus (AP) in H than in L. The bacterial communities in H presented greater stability (characterized by a higher 1-AVD index and more complex networks) and greater core bacterial diversity (as indicated by a higher Shannon index), with distinct compositional clustering between sites (PERMANOVA, P < 0.001, permutations = 999). RDA indicated that AP was strongly correlated with bacterial community structure (R²=0.7638, P = 0.009) and that H was enriched with putative phosphorus-transforming taxa (e.g., Arthrobacter and Thauera ). Hierarchical partitioning highlighted bacterial communities as the primary driver of growth differences, followed by AP. However, fungal communities failed to exhibit strong correlations with the aforementioned factors and showed no significant differences themselves. Conclusions These findings revealed that the greater stability and diversity of the bacterial community in H likely created conditions conducive to the enrichment of putative phosphorus-transforming taxa (e.g., Arthrobacter and Thauera ), whose abundance was strongly correlated with garlic growth. This process likely enhanced the conversion of unavailable soil phosphorus to available phosphorus (AP), thereby promoting more vigorous garlic growth in H. Furthermore, L was enriched with presumptive phytopathogenic fungi (e.g., Fusarium and Penicillium ), which may correlate with the observed growth inhibition of garlic and could help explain the growth differences between the two sites. Collectively, these results indicate that microbial stability may maintain phosphorus-transforming functions to sustainably ensure phosphorus availability. Our study provides insights into optimizing garlic cultivation by targeting the regulation of rhizosphere phosphorus-transforming bacteria and improving microbial community stability, particularly for garlic under long-term continuous cropping.

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