IN VITRO RESPONSE AND MORPHOLOGICAL VARIABILITY OF FOUR EXOTIC TOMATO VARIETIES (Solanum lycopersicum L.) TO TOXIN FILTRATES OF TOMATO WILT FUNGI

Résumé

A study was carried out to evaluate morphological variability and response of four exotic tomato varieties, namely; Copernic f1, Lindo f1, Cobra f1 and Kiara f1 to fungal wilt in Lafia, Nasarawa State, Nigeria. Healthy leaves collected from 8 weeks old tomato seedlings were inoculated with 21-day old culture filtrates of Colletotrichum gloeosporiodes, Pythium spp. and Fusarium oxysporum, and observed for 3 days for the development of leaf necrosis and yellowing. All four varieties were susceptible to disease initiation by crude
toxin filtrates of the wilt fungi. Lindo f1 was the least susceptible with 33.33% leaf necrosis and 29.17% leaf yellowing. Leaves of Cobra f1 were the most susceptible to necrotic symptoms (72.92%), while the highest incidence of leaf yellowing (79.17%) was observed in filtrate-inoculated leaves of the Kiara f1 tomato variety. Differences in mean disease incidence among the evaluated tomato varieties were significant (P ≤ 0.05). Fusarium oxysporum was the least pathogenic, inducing 30.00% leaf necrosis and 36.25% leaf yellowing.
Pythium spp. induced the highest incidence of leaf necrosis and leaf yellowing (56.00% respectively). Kiara f1 had the highest plant height (34.40cm), leaf area (40.70cm2) and stem girth (6.20mm)