Bacterial inoculation modulates maize growth and yield components across nitrogen fertilization levels under greenhouse conditions

Abstract

Plant-growth-promoting bacteria (PGPB) may complement mineral fertilization and contribute to sustainable maize production, although their effects depend on nutrient availability and bacterial strain. The effects of Peribacillus sp. B5 (A; GenBank OP861655), Sporosarcina sp. NSM3 (B; OP861656), and their co-inoculation (A+B) on maize growth, foliar nutrient status, biomass, and yield components were evaluated under different nitrogen (N) levels. A greenhouse experiment used a completely randomized 4×4 factorial design with four replicates, combining four inoculation treatments with 0, 50, 75, and 100% of the calculated N requirement. Significant inoculation × N interactions occurred for plant height, leaf area, ear insertion height, ear length and diameter, shoot dry matter, kernels per longitudinal row, rows per ear, and grain weight per ear. Peribacillus sp. without supplemental N produced the highest shoot dry matter (87.41 g per pot), 61.6% greater than the non-inoculated 0% N control. A+75% N produced the highest grain weight per ear (49.05 g per ear), compared with 21.72 g per ear in the non-inoculated 75% N treatment, while B+50% N produced 47.50 versus 11.72 g per ear in the corresponding control. Chlorophyll content and foliar N were unaffected by inoculation, N fertilization, or their interaction, whereas foliar P responded to N fertilization and K to inoculation. Overall, maize responses depended on specific strain × N combinations, identifying A+75% N and B+50% N as promising for field evaluation. These findings support complementary bacterial inoculation under reduced N fertilization but do not demonstrate N fertilizer replacement or increased N-use efficiency.