<p>Fusarium wilt and damping off are among tomatoes’ most devastating soil-borne diseases. This study investigates the remedial effects of <i>Trichoderma virens</i> and jasmonic acid on pigments, gaseous exchange and stomatal responses in pathogenically inoculated tomato plants. For experimentation, tomato seeds were primed with <i>T. virens</i> and jasmonic acid and germinated for thirty days in a plant growth chamber. Subsequently, these seedlings were then exposed to pathogen inoculations of <i>Fusarium oxysporum</i> f. sp. <i>lycopersici</i> (Fol) and <i>Rhizoctonia solani</i> (Rs) in twelve different sets of treatments in a random block design in the experimental fields of Lovely Professional University, Phagwara, in the year 2022–23. Pathogen infections caused a marked decline in photosynthetic pigments along with concomitant decreases in carotenoids and soluble sugars. Both pathogens also significantly impaired photosynthetic rate, transpiration rate, intercellular CO₂ concentration, and stomatal conductance, which are associated with decreased stomatal aperture. In contrast, total anthocyanin content increased in infected plants, with a moderate rise in Fol-treated plants (12.4%) and a pronounced increase under Rs stress (3.2-fold), suggesting activation of stress-related protective responses. Seed priming with <i>T. virens</i> and jasmonic acid markedly alleviated these adverse effects, restoring overall photosynthetic efficiency and stomatal behaviour. This experimental analysis showed that seed priming with <i>T. virens</i> and jasmonic acid effectively decreases pathogen damage and improves tomato resistance to fusarium wilt and damping-off diseases.</p> Graphical abstract <p></p>