Early blight, caused by Alternaria alternata, is a major tomato disease that leads to significant economic losses. This study aimed to evaluate the effectiveness of two fungi, Funeliformis mosseae and Trichoderma harzianum, as potential biological control agents against the disease. Initially, the inhibitory effect of T. harzianum on the pathogen's colony growth was assessed under laboratory conditions using the dual-culture method, where T. harzianum reduced pathogen colony growth by 70%. Subsequently, the efficacy of F. mosseae and T. harzianum, applied individually and in combination, was tested against A. alternata in greenhouse conditions using a completely randomized design with three replications per treatment. Various parameters were measured, including chlorophyll a, b, and total content; total phenol; activities of catalase and peroxidase enzymes; and plant growth traits such as stem number, stem height, fresh and dry weight of aerial parts, root length, and fresh and dry weight of roots. Statistical analysis revealed that the application of T. harzianum and F. mosseae enhanced antioxidant enzyme activity (catalase and peroxidase) and phenolic compound levels, leading to improved growth and increased dry matter content in tomatoes under pathogen infection conditions.
