Abstract: In order to clarify the mechanism of Periploca Sepium seed germination under drought stress and different storage time, different concentrations of polyethylene glycol (PEG) were used to simulate drought stress condition and germination period of comparison tests were carried out on three different storage time seeds. The total germination rate, germination force, vitality index and radicle growth were observed and the drought resistance was analyzed. The results showed that: different levels of drought stress and storage time had a certain influence on seed germination. Five percentages of PEG-6000 could promote the one-year seeds germination rate and germination force, mildly suppressed two-year seeds, greater influenced three-year seeds. When PEG-6000 concentration was higher than 5%, the germination rates and germination forces of three kinds of seeds decreased, while little seed germinated when the stress concentration increased to 25%. The vitality index and radicle growths of three kinds of seeds decreased, in particular in different water stress, the biggest drop was three-year seed. The best germination condition was storage for one to two years seeds in PEG-6000 5%-15%, and seeds storage for 1 year better than 2 years seeds, 3 years seeds was the worst. The drought-tolerance of three kinds of seeds decreased in the following order: storage 1 year seeds>2 years seeds>3 years seeds.

Key words: Periploca sepium, total germination rate, germination force, vitality index, radicle growth