Screening of key rhizosphere microorganisms in wheat and their role in reducing nitrogen application and increasing yield

Key message This study identified key rhizosphere microorganisms that significantly increase wheat yield and reduce reliance on nitrogen fertilizers, promoting sustainable wheat production. Abstract Wheat is fundamental to global grain production and food security. While nitrogen fertilization enhances wheat productivity, its excessive application induces a series of ecological and environmental issues. Rhizosphere microorganisms play pivotal roles in facilitating nutrient acquisition, plant growth, development, and stress resistance. Consequently, biological approaches aimed at boosting wheat yield while diminishing reliance on chemical fertilizers are of significant importance. In this study, we utilized microbiome analysis to examine the structure, composition, and assembly processes of the rhizosphere microbial community under low- and normal-nitrogen conditions at both flowering and maturity stages. The results indicated that the microbial community was most stable under normal nitrogen at maturity, with the genus Bacillus displaying the highest relative abundance. Thirty-six rhizobacterial strains exhibiting plant growth-promoting traits were isolated and screened. Among them, the key functional strains Bacillus toyonensis 12H57 and Priestia aryabhattai 10,901 showed 100% similarity to ASV690 and ASV1, respectively. Pot experiments demonstrated that inoculation with strains 12H57 and 10,901 significantly enhanced nitrogen and phosphorus accumulation in wheat. Field trials further confirmed that both strains substantially increased the yield of several major wheat cultivars, including Jimai 22 (JM22), JM899, and Changle 5 (CL5). Under normal nitrogen conditions, strains 12H57 and 10,901 elevated the average wheat yield by 29.48% and 46.69%, respectively. Under low nitrogen conditions, the average yield reduction was 24.27%, which was alleviated to 13.21% following bacterial inoculation. This study identifies key rhizosphere strains associated with nitrogen use efficiency in wheat, providing a theoretical foundation and technical support for reducing chemical fertilizer application and enhancing sustainable wheat production.