Abstract: The effects of high temperature 38 ℃/21 ℃（day/night）on plant growth，leaf chlorophyll content，relative electric conductivity（REC），malon dialdehyde（MDA）content，relative water content（RWC），the activities of superoxide dismutase（SOD），peroxidase（POD），catalase（CAT）and ascorbate peroxidase（APX）were investigated in 9 marigold cultivars. The results showed that 9 cultivar seedlings showed different degrees of damage symptom under high temperature for 4 days. MDA contents and REC increased significantly，whereas leaf chlorophyll content，RWC and APX decreased under high temperature treatment，which also increased SOD，POD and CAT activities. The path coefficient analysis showed a significantly positive correlation between REC and heat injury index，but significantly negative correlations between SOD，POD and CAT activities and heat injury index. The heat tolerance of the tested 9 cultivars decreased in the order of‘Discovery’，‘Chokdee’，‘Giant’，‘Gate Gold’，‘Great Hero’，‘Janie’，‘Durango’，‘Little Hero’and‘Bonanza’.

Key words: french marigold, marigold, cultivar, heat stress, heat tolerance, antioxidant enzyme