Abstract: A comparative observation was carried out on the changes of anatomical structure and starch content in the leaves of Euonymus radicans 'Emorald Gold' during overwintering and cold acclimation, and the photosynthesis-light response curves from the leaves of unacclimated and acclimated seedlings as well as the leaf photosynthetic rate of acclimated and unacclimated seedlings treated at the low temperature stress were studied comparatively. The results showed that the appearance of vacuole division during overwintering and cold acclimation were highly correlated to the development of plant cold-resistance. So were the starch accumulation before the acclimation, the starch degradation after the acclimation and starch accumulation again after de-acclimation. Compared with unacclimated seedlings, the leaf photosynthetic rate and photosynthetic light compensation point of acclimated seedlings decreased, photosynthetic light saturation point increased slightly. The leaf photosynthetic rate of acclimated seedlings still maintained at a higher level after low temperature stress for 72 h, but that of unacclimated seedlings became negentropy, indicating that cold acclimation raised the stability of photosynthesis of seedlings under low temperature stress. And the relation between the above-mentioned adaptive changes and plant cold-resistance was also discussed.

Key words: Euonymus radicans ‘Emorald &, Gold’, overwintering, cold acclimation, adaptive, cold-resistance