Physiological and molecular responses of broccoli to Trichoderma viride and fertilization

Abstract

This study investigated the physiological and molecular responses of broccoli (Brassica oleracea var. italica) to the application of the biocontrol fungus Trichoderma viride in combination with nitrogen fertilizer as a chemical fertilizer and Vit-Org VG as an organic fertilizer. The aim was to evaluate the integrative effects of these treatments on plant growth, physiological performance, and gene expression related to growth and metabolic activity. A controlled experimental design was used with treatments including sole and combined applications of T. viride, nitrogen fertilizer, and Vit-Org VG. Results indicated that the combined treatments significantly enhanced vegetative growth parameters, including plant height, leaf area, and biomass accumulation, compared with individual applications and control. Physiological analysis revealed improvements in chlorophyll content, photosynthetic efficiency, and nutrient uptake efficiency under integrated treatments. Molecular analysis using qRT-PCR demonstrated distinct temporal expression patterns of growth-related genes. MDH exhibited a rapid upregulation at 1 dpt followed by a decline, indicating early metabolic activation, whereas BoTLP1 showed a progressive and sustained increase, reaching higher expression levels at later stages. Importantly, the combined treatment induced the highest expression levels of both genes across all time points, suggesting a strong synergistic regulatory effect on gene activity. Overall, the most pronounced improvements were observed in the combined treatment of T. viride with nitrogen fertilizer and Vit-Org VG, highlighting synergistic interactions that enhance both physiological performance and molecular regulation. These findings demonstrate the potential of integrating beneficial microbes with specific fertilization strategies to improve broccoli productivity in a sustainable manner.