GERMINATION, SEEDLING VIGOR AND ELECTRICAL CONDUCTIVITY OF SEED LEACHATES AS AFFECTED BY DRY HEAT TREATMENT OF TOMATO SEEDS

Seed dormancy is a major problem in tomato (Lycopersicon esculentum Mill.). Dry heat treatments at 40, 50 or 60°C for 24h were applied to assess their ability to break dormancy and invigorate seeds of four tomato cultivars (‘Nagina’, ‘Pakit’, ‘Riogrande Improved’ and ‘Roma’). All the cultivars responded similarly. Dry heat treatments at 40 and 50°C resulted in improved germination and seedling vigor compared to untreated seeds, with the highest vigor observed in seeds treated at 50°C. However, seeds dry heat treated at 60°C behaved similarly in terms of germination and vigor to untreated seeds. In all cultivars, seeds dry heat treated at 50°C resulted in lower electrical conductivity of seed leachates, whereas the leachate conductivity of seeds dry heat treated at 40°C was generally not as low.