Abstract
Orchids of Brassolaeliocattleya Chian-Tzy Emperor (Cattleya) and Cymbidium Sazanami were cultured at 32/20°C, 30/15°C, and 28/8°C (maximum/minimum temperature) for 2 months. It was found in Cattleya leaves that superoxide dismutase (SOD), ascorbate peroxidase (APX) and catalase (CAT) activities were lower than in Cymbidium leaves, while polyphenol oxidase (PPO) and ascorbate oxidase (AOX) activities were higher. The high cultural temperature enhanced activities in all enzymes in Cattleya and in four enzymes except CAT in Cymbidium, indicating that it greatly affects scavenging enzyme activities compared to the low temperatures which induced only an increase in APX activity in Cattleya and a decrease in CAT activity in Cymbidium. PPO activity increased and AOX decreased in both orchids at the low temperature. Cattleya leaves at both high and low cultural temperatures decreased ascorbic acid, while Cymbidium increased it. Cattleya at the low temperature increased markedly SH-containig substances but the latter at the high temperature decreased these substances. Lipid peroxides increased in Cymbidium leaves under both high and low temperatures, but for Cattleya neither temperature conditions affected lipid peroxides.
