Enhancing N use Efficiency, Increasing Wheat Yield and Reducing Chemical Fertilizer Dependence via Beneficial Bacteria

Rising food demand has led to heavy use of chemical fertilizers, which are costly and pose serious threats to soil health and the environment. This two-year field study evaluated whether integrating beneficial bacteria with reduced nitrogen (N) fertilizer could improve soil health, wheat productivity, and N use efficiency (NUE), thereby reducing dependence on chemical N inputs. Nine treatments were tested, including combinations of no N (CK), 50% (N50) and 100% (N100) recommended N rates, with or without soil application and seed inoculation using beneficial bacteria (SAB and SIB). Results demonstrated that seed inoculation with beneficial bacteria (particularly N50 + SIB and N100 + SIB) significantly enhanced soil ammonium and nitrate contents, microbial biomass carbon (MBC), dissolved organic carbon (DOC), and soil enzyme activities at critical growth stages compared to uninoculated controls. These improvements in soil health translated into better plant physiological functioning, evidenced by increased chlorophyll content, higher antioxidant enzyme activities (CAT, POD, SOD, GSH), and reduced membrane injury. Consequently, beneficial bacteria inoculated treatments improved N accumulation and translocation efficiencies, with N100 + SIB showing the highest N accumulation at maturity and its contribution to grain. Grain N content and 1000-grain weight were substantially improved with bacterial treatments, with N100 + SIB achieving a 15-20% increase in protein content and the highest grain yield (5705-5760 kg/ha). Notably, N50 + SIB achieved comparable grain yield and quality improvements as N100 alone, highlighting a promising reduction in chemical N dependency. Moreover, bacterial treatments enhanced PFPN, NUPE, and NIE by 16-34% over conventional N treatments, and the N harvest index (NHI) exceeded 67% in N100 + SIB, indicating efficient N partitioning into grain. In summary, seed inoculation with beneficial bacteria significantly improved soil health, plant growth, and N utilization, allowing for reduced application of synthetic N fertilizers without compromising wheat yield or grain quality. This suggests a sustainable and eco-friendly strategy for enhancing N use efficiency in wheat production.