Tomato production is significantly harmed by the interruption of fungal pathogens, i.e., Alternaria solani, the causal agent of early blight, which is responsible for substantial yield losses in tomato crops. In recent years, the application of silver-based green synthesized nanomaterials (AgNMs) has been documented as the best performer against various plant diseases. However, the knowledge about applying green-synthesized AgNMs for the management of early blight and its impact on the components of the antioxidant defense system, especially in tomatoes, still needs to be discovered. Therefore, in the current study, two green synthesized viz. wild gourd (Citrullus colocynthis) and rough cocklebur (Xanthium strumarium) AgNMs were applied at three different concentrations to check their efficacy against the early blight of tomatoes and the components of the antioxidant defense system of tomato plants. Results revealed that C. colocynthis-based AgNMs were found to be most effective and exhibited disease incidence of A. solani (22%) with a significant increase in tomato production (13%) along with the number of fruits/plants. Moreover, application of C. colocynthis-based AgNMs improved the concentration of ascorbic acid (1240, 997 µg/mL), total phenolic contents (950, 800 µg/mL), flavonoids (111, 88 mg/g), hydrogen peroxide (0.0013, 0.001 U/mg), amylase (110, 89 U/mL), chlorophyll a (0.31, 0.25 mg/g), chlorophyll b (0.22, 0.16 mg/g), and total chlorophyll (0.61, 0.50 mg/g) in treated plants of resistant and susceptible varieties of tomato respectively, than that of control. It is concluded that applying green synthesized AgNMs may be a viable alternative to synthetic chemicals for managing the early blight of tomatoes.
