Abstract:
The tillering stage is a critical transition from vegetative growth to yield formation in rice. To clarify the relationships among rhizosphere soil nutrients, enzyme activities, microbial community characteristics, rice yield, and potential pathogenic risk at this stage, a field experiment was conducted using the local conventional cultivar Lingxiangsimiao (LX) and seven early-maturing rice cultivars provided by the Rice Research Institute, Hunan Academy of Agricultural Sciences, namely Hfan 1, Hfan 10, Hfan 12, Hfan 24, Hfan 31, Hfan 32, and Hfan 75, designated as H1, H10, H12, H24, H31, H32, and H75, respectively. Rhizosphere soil physicochemical properties and enzyme activities were systematically determined, and the structures of dominant bacterial and fungal communities, together with the relative abundances of representative pathogen-associated genera, were analyzed. The results showed that the grain yields of H10, H31, and H75 were 13.3%, 16.3%, and 11.9% higher than that of LX, respectively, whereas no significant differences were observed between LX and H1, H12, H24, or H32. Compared with LX, H10 increased the concentrations of rhizosphere soil alkali-hydrolyzable nitrogen and available potassium by 25.6% and 41.6%, respectively. Firmicutes was identified as the main differential bacterial taxon in H10, with a relative abundance of 5.23%, compared with 2.40% in LX. Regarding pathogen-associated genera, the relative abundances of
Alternaria,
Curvularia,
Gaeumannomyces, and
Cladosporium in H10 were 0.002%, 0.138%, 0.245%, and 0.007%, respectively, all lower than those in LX (0.096%, 0.209%, 0.848%, and 0.245%, respectively). In H75,
Microbotryales was the main differential fungal taxon, and the relative abundance of
Penicillium reached 5.98%, higher than that in LX (3.35%). Meanwhile, the relative abundances of
Alternaria,
Curvularia,
Gaeumannomyces, and
Cladosporium in H75 were 0.002%, 0, 0.265%, and 0.019%, respectively, all lower than those in LX. In conclusion, significant differences were observed among rice cultivars in rhizosphere nutrient status, microbial community structure, and the distribution of pathogen-associated taxa during the tillering stage. Among the tested cultivars, H10 showed superior performance in enhancing soil available nutrients and achieving higher grain yield, whereas H75 exhibited lower abundances of pathogen-associated genera. These findings provide a theoretical basis for screening rice cultivars with both high yield potential and a healthy rhizosphere microbial community.