Abstract:The changes in some physiological characteristics in two cultivars of Amaranthus tricolor L., such as ‘Red flower’ and ‘Green leaf’, were investigated under 40℃ for 6 days. The results showed that the contents of soluble sugar and praline, the activities of polyphenol oxidase (PPO) and peroxidase (POD) were enhanced in ‘Red flower’ under high temperature, compared with ‘Green leaf’, while amaranthine content in ‘Red flower’ was remarkably accumulated under 40℃. The ‘Green leaf’ exhibited sensitively to high temperature, in which the content of amaranthine decreased, malondialdehyde (MDA) content and membrane leakage rate increased, as well as the visible damage symptom appeared during heat stress. In comparison with, the content of total phenolic in leaves of two cultivars under 40℃ had no significant difference from that in the control under 30℃. It was suggested that the accumulation of osmoregulatory matter and amaranthine, and enhancement of the activities of enzymes might be the physiological basis of ‘Red flower’ resistanted to heat stress.
