Selenium-enriched Trichoderma harzianum DEMf 1V: a multifunctional biofertilizer for wheat biofortification and growth promotion

Abstract Selenium (Se) is an essential yet globally scarce element, and microbial vectors offer an innovative method for augmenting Se bioavailability in crops. Trichoderma harzianum DEMf 1V and Тrichoderma citrinoviride DEMf: TR3 were grown in nutrient media with 2.5 and 5 mg Se l−1 to obtain Se-enriched biomasses. T. harzianum DEMf 1V accumulated the highest Se amount, 1262.50 µg g−1 DW. In a pot experiment, Se-enriched T. harzianum DEMf 1V used as a wheat biofertilizer, induced a 70% higher Se content than seedlings fertilized with Na₂SeO₃. The results verified the growth-promoting effects of T. harzianum DEMf 1V and Se-enriched T. harzianum DEMf 1V, whose application caused higher biomass production (47 and 55%, respectively) and chlorophyll content (23 and 42%, respectively) compared with the control. Fungal biochemical characteristics confirmed Se as a factor that modulates enzymatic profiles and volatile organic compounds production and stimulates auxin production, suggesting a potential synergistic interaction between Se enrichment and plant growth-promoting mechanisms. The presented results demonstrated that Se enrichment of T. harzianum produced a multifunctional biofertilizer that represents a source of Se and a potent tool for amplifying the plant growth-promoting effects of Trichoderma spp.