Abstract: Seedlings of Lilium longiflorum‘Snow Queen’were treated in chambers with temperatures of 35℃/30℃, 37℃/32℃, 39℃/34℃ for 1, 2, 4, 8, 16 and 32 h, respectively. The changes of the morphology and contents of proline, MDA, soluble protein as well as relative electrical conductivitywere determined. The results showed the contents of proline and MDA, the relative electrical conductivity increased significantly by 37℃/32℃ treatment. Those indexes had a remarkable correlation and could be taken as heat tolerance indexes. The change in morphology of the seedlings under 37℃ treatment was also consistent with that of physiological indexes. The physiological indexes of 35℃ and 39℃ treatment didnpt have significant correlation.

Key words: Lilium longiflorum, Heat stress, Free proline, Malondialdehyde (MDA), Soluble protein, Relative electrical conductivity