The seed desiccation tolerance of Chinese buckeye and seedling frost hardiness of both Chinese buckeye and Red buckeye were studied in the year 2003. The results showed as follows:1. Chinese buckeye seeds are recalcitrance which are of high desiccation-sensitivity. The seed moisture content taken from ripened fruits is higher than 60%. When the seeds were naturally dried for 30 days, their moisture content was declined to 30.2% and their viability was completely lost2.with the decrease of seed moisture content, the seed germination percentage and seedling biomass increased. Meanwhile, the activity of superoxide dismutase (SOD) declined slighthy, and relative conductivity, malondialdehyde (MDA) and soluble sugar content increased. However, when seed moisture content is lower than 53.7%, the seed germination percentage and seedling biomass as well as SOD activity decreased with the decrease of seed moisture content. In the meanwhile, the relative conductivity, MDA content and soluble sugar content arose.3. When seed moisture content is from 47 % to 60%, the seed germination percentage is high and it was thought that this is the better moisture content for maintaining Chinese buckeye seed viability.4.There were not significant differences between the relative electrical conductivity of Chinese buckeye's top buds and that of Red buckeye's top bud before they were treated with low temperature. With the decrease of treated temperature in the same treated hours or with the extend of treated hours when they were treat with the same low temperature, the relative electrical conductivity of both species increased gradually, but the increase level of Red buckeye was less than that of Chinese buckeye. With the same treated temperature and hours, the relative electrical conductivity of Red buckeye's top buds were always lower than that of Chinese buckeye. This indicated that the cold-resistantance of Red buckeye is evidently stronger than that of Chinese buckeye.5. The top buds of two species have many little vacuoles. Lots of high electron-density black granule, vesicle, autophagic vacuoles and annulate lamellae were observed in vacuoles. As the treated temperature decreased and the treated hour extended, the Red buckeye's cells got much more these structures, however, Chinese buckeye's cell did not. And these structures were always more in Red buckeye than in Chinese buckeye.6. A few proteins were observed in cells of Red buckeye when they were treated at - 18℃ within 24h. The Red buckeye's cells got more proteins when treated at - 18℃ within 72h, and there were many proteins when treated at - 30℃ within 24h. However, Chinese buckeye's cell got a few proteins and most of the cells had degraded, when treated at the same condition.7. Lethal temperature and freezing hour of Chinese buckeye's top bud is - 18℃ within 72h, and that of the Red buckeye is - 18℃ within 168h, - 30℃. within 168h.8. Based on the systematical analyses, the cold-resistance of the Red buckeye is better than that of Chinese buckeye. |