Bioprotective role of Trichoderma viride in improving Abelmoschus esculentus growth and yield under wastewater irrigation and dual biotic-abiotic stress.

Irrigation water quality markedly shapes plant growth and physiological functioning, particularly under integrated biotic and abiotic stresses. This study evaluated the influence of irrigation water types, tap water (TW), domestic wastewater (DWW), Lyari wastewater (LWW), and Malir wastewater (MWW), interacting with wastewater-isolated bioprotectant Trichoderma viride on Abelmoschus esculentus infected with soil-borne pathogens Fusarium oxysporum and Rhizoctonia solani. Morphological traits, together with ITS amplicon sequencing and BLAST analysis, confirmed T. viride (PZ212855). Plants treated with LWW and T. viride showed pronounced enhancements in agronomic and physiological traits, i.e., enhanced plant height (101.25 ± 2.87 cm), fresh biomass (24.04 ± 0.86 g), dry biomass (8.45 ± 0.32 g), leaf number (20.25 ± 0.75), fruit fresh biomass (14.33 ± 0.55 g), chlorophyll a (2.12 ± 0.0 4 mg/g F.wt), chlorophyll b (1.30 ± 0.02 mg/g F.wt), total chlorophyll (3.42 ± 0.02 mg/g F.wt), carotenoids (0.75 ± 0.02 mg/g F.wt), and total soluble proteins (1.66 ± 0.02 mg/g F.wt). These increases corresponded with the greater nutrient content of LWW and DWW, which met FAO irrigation standards. DWW upgraded plant functioning, but its slightly higher arsenic concentration required mitigation using T. viride in the rhizosphere. MWW, exhibiting greater physicochemical loads and higher arsenic, generated oxidative stress, increased H2O2 (2.74 ± 0.01 nm/g F.wt) and MDA (0.97 ± 0.03 nm/g F.wt), and reduced growth. T. viride partially mitigated these effects by regulating antioxidant enzyme activity. Overall, integrating nutrient-rich wastewater with T. viride improved plant growth, yield, and stress resilience under challenging conditions.