METHOD: Life Cycle CONDITIONS: Green House - 18h light at 35-42C in hot house (held at 30C overnight) and 30-40C in ventilated house (allowed to drop to 15-25C at night) METHOD NARR: Two plastic GH's were used. One was ventilateintained at a relatively high temperature. Plants were grown for 25-30 days under these conditions. Plants were assessed for vigor using a 1-9 scale (where 9 = absence of heat stress symptoms and 1 = complete necrosis) by tcolor, necrosis, chlorosis, leaf rolling, leaf angle, plant size and leaf size. The plants were cut at the soil line and weighed as an indication of shoot growth. Those plants showing some heat tolerance were transferred to shzation. Tuberization of bud cuttings was measured on a 1 to 5 scale where 5 was lowest induction and 1 was highest. RESULTS NARR: Accessions were deemed heat tolerant if an average vigor rating in the hot house >6, and either a fre or an average fresh weight in the hot house > the mean for all accessions grown in the hot house. Higher tuberization ratings indicate less induction to tuberize in the hot house. AUTHOR EXPLANATION: An accession withse and a high ratio of hot to ventilated fresh weight would be considered relatively insensitive to heat stress, whereas a high fresh weight but a low fresh weight ratio would indicate an accession with overall growthsitivity to heat stress. Induction of tuberization in leaves is not necessarily a reliable indicator of final tuber yield as tuberization can be inhibited by high soil temperature.