Molybdenum Trioxide Nanoparticles Enhance Wheat Tolerance to Salinity and Temperature Stress by Promoting Rhizobacterial Phytohormone Production and Preserving Photosynthetic Pigments

Abstract

Climate-driven soil salinization and temperature extremes increasingly threaten global wheat production, yet conventional mitigation strategies are limited by poor bioavailability and environmental trade-offs. This study synthesized molybdenum trioxide nanoparticles (MoO₃NPs) stabilized with four chemically distinct agents (amylopectin, methylcellulose, lysine, cocamidopropyl betaine) and systematically evaluated their stabilizer-dependent effects on a rhizobacterial consortium (Ensifer meliloti, E. mexicanus, Rhizobium tropici) and on wheat (Triticum aestivum) under salinity (-5% NaCl) and temperature (-10 °C to + 50 °C) stress. Density functional theory calculations revealed binding energies > 70 kcal/mol for all stabilizers, with methylcellulose (MC) showing optimal electronic coupling (η ≈ 0.07 eV). FTIR and SEM confirmed stabilizer-specific surface functionalization and morphology. MC-MoO3NPs uniquely enhanced bacterial growth and metabolite production, increasing indole-3-acetic acid by u to 95%, gibberellic acidby 139%, and siderophore by 25% without toxicity. Wheat seed priming with MC-MoO3NPs (1.0 µg/mL) significantly improved germination, stem length, biomass, and photosynthetic pigments (chlorophyll a/b, carotenoids) under stress conditions At 2.5% NaCl, treated plants sowed 55% longer stem and 90% higher biomass than controls; at -10 °C and + 50 °C, stem length increase by 125 and 83%, respectively. Correlation clustermaps confirmed tight coupling between preserved photosynthetic capacity and growth. MC-MoO3NPs could represent a sustainable nano-biostimulant for climate-resilient wheat production.