Cultivar-dependent physiological response of tomato to Fusarium oxysporum under controlled greenhouse conditions

Fusarium oxysporum is one of the most important soil-borne pathogens limiting tomato production under protected cultivation systems. Disease severity depends on the interaction between pathogen aggressiveness and host susceptibility, while vascular infection may also impair physiological processes related to photosynthesis and plant vigor. This study evaluated the cultivar-dependent response of six tomato cultivars to Fusarium oxysporum isolates FO23 and FOL43 under controlled greenhouse conditions and quantified physiological damage through changes in chlorophyll a, chlorophyll b, and carotenoid content. Montagano and San Marzano Nano were the most susceptible cultivars, showing the highest mortality and strongest symptom expression. Commercial cultivars declared resistant to races 0 and 1 showed effective resistance to FOL43 but only partial protection against the local isolate FO23. Pigment analysis revealed marked reductions in chlorophyll a, chlorophyll b, and carotenoids in most cultivars, whereas N507 showed the lowest physiological damage and maintained comparatively higher pigment stability. Disease severity differed markedly among cultivars and was closely associated with physiological impairment. The aggressive local isolate FO23 caused stronger reductions in photosynthetic pigments than FOL43, indicating a greater capacity to disrupt host physiological processes. The integration of visual disease assessment and pigment quantification provided a robust framework for evaluating cultivar tolerance under greenhouse conditions. These findings support cultivar screening, resistance evaluation, and integrated management strategies for greenhouse tomato production.