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Screening for Chilling Resistance in Tomato Seedlings


Seedlings of a high-altitude form of the wild tomato Lycopersicon hirsutum Humb. & Bonpl. were able to develop the first true leaf when grown at a night temperature of 0°C (16 hours) and a day temperature of 20° (8 hours). Cultivars of L. esculentum Mill, developed poorly or not at all beyond the cotyledon stage under these conditions. The species were crossed and some selections from the second backcross to L. esculentum also were able to develop first true leaves when exposed to the low night temperatures. These gave progeny which approached or equalled the performance of the wild species, indicating that this cold resistance can be transferred from L. hirsutum to L. esculentum using low night temperature as a nondestructive screening technique.