Synergistic Effects of 5-Ureidohydantoin, Rhizobacteria and Non-wood-Based Biochar on Barley Productivity Under Drought and Multiple Toxic Metals Stress.

Barely (Hordeum vulgare L.), an essential crop accounting for roughly 15% of global caloric consumption, confronts substantial risks from toxic metal pollution, especially drought stress, (Pb) and mercury (Hg) stress, endangering global food safety. The current research sought to examine synergistic impacts of abovementioned stressors and efficacy of 5-ureidohydantoin, rhizobacteria and non-wood-based biochar in promoting barley growth. Experimental design comprised 24 treatment combinations featuring drought stress, Pb stress (5 mg/kg) and Hg stress (250 and 500 mg/kg) with diverse administrations of biochar and 5-ureidohydantoin. Rhizobacteria and 5-ureidohydantoin combination increase barley growth by promoting root development, enhancing nutrient absorption and improving overall vitality, with 5-ureidohydantoin facilitating cell division and elongation, while rhizobacteria enhance nutrient accessibility and root integrity, resulting in an expedited germination process, flowering and yields. Barley seeds cv. TJ-70, subjected to Agrobacterium rhizogenes treatment, exhibited notable growth parameters, with root lengths measuring 10.01 cm under 5 mg/kg Pb stress than 6.31 cm in control group. The treatment enhanced root and shoot FW by 23.7% 25.71%, respectively, whereas chlorophyll content reached a maximum of 2.69 mg/g at 5 mg/kg Pb. Research revealed that plants exposed to rhizobacteria and 5-ureidohydantoin had substantial enhancements in germination rate (over 85%), root length (averaging 27 cm), shoot length (averaging 29 cm) and total biomass in comparison to control treatments. The simultaneous application of 5-ureidohydantoin and jute-biochar exhibited significant promise for enhancing barley's resistance to metals and drought stresses by increased chlorophyll levels and decreased EL in amended plants. Furthermore, electrolyte leakage diminished to 11.4%, and the vigor index enhanced to 1601.09 under Pb stress. These data suggest that biochar and 5-ureidohydantoin use can alleviate detrimental impacts of environmental stresses on barley. Extending this study to encompass various crops will facilitate evaluation of wider relevance of these results; thereby fostering integrated crops management tactics utilize stimulants such as rhizobacteria and 5-ureidohydantoin in conjunction with organic and inorganic amendments, ultimately enhancing agricultural resilience and global food security.