濒危植物水青树种子的生物学特性

通过连续三年（2006～2008）对水青树种子（Tetracentron sinense）的形态特征和生理特性等指标进行检测,探讨了不同储藏温度、时间和不同基质对水青树种子萌发的影响,分析了与种子生物学特性相关的濒危机制。水青树种子很小,其形态特征、千粒重、含水量和饱满度在不同年限间差异不显著,而吸水速率却差异显著,其中2007年种子的吸水速率最快。TTC染色测得3年水青树种子的活力几乎为0,但其活力指数分别为0、0.41和0.27,表明TTC染色法不适于水青树种子活力的估算。低温储藏后,3年种子的萌发率分别为1.25%、96.5%、70.8%,发芽势分别为1%、59.8%、41.8%。随储藏时间的增加,2007年种子活力降低的速度都慢于其它2年,低温储藏的种子活力降低速度慢于常温储藏的种子。不同基质对水青树种子的萌发和幼苗的生长有一定影响。结果表明,大年水青树种子的活力明显强于小年,随储藏时间的增加其活力的丧失速度也慢于小年;低温储藏有利于种子活力的保持。种子生物学特性方面导致水青树更新困难的原因可能有以下几点：（1）长期进化形成的小种子虽有利于传播和散布,但不利于种子和幼苗的存活;（2）长期低温不适于种子萌发,难以形成应有的幼苗格局;（3）长期湿润环境不适于种子安全度过寒冷期。

Biological Characteristics of Seeds of Endangered Plant Tetracentron sinense(Tetracentraceae)

By detecting the indicators of seeds such as the morphology and physiological characteristics within three consecutive years,the effects of different storage temperatures and time,and different media on seed germination of Tetracentron sinense were discussed,and also the endangered mechanism associated with biological characteristics of seeds was analyzed. The seeds of T.sinense were very small. No significant difference existed associated with seed morphology,1000-seed weight,water content and plumpness,except for water absorption rate among seeds from different year,and the water absorption rate of seeds from 2007 was the fastest. The TTC results showed that the percentage of seed vigor was close to zero,but the vigor index of seeds among different year was respectively 0,0.41 and 0.27,which indicated that TTC was not suitable for the estimation of T.sinense seed vigor. After stored at lower temperature,the germination rate of these seeds was respectively 1.25%、96.5%、70.8%,and the germination force was 1%、59.8%、41.8%. With the increase of storage time,seeds vigor of three years would decrease gradually,but the loss rate of seed vigor from 2007 was the slowest compared with other years. After stored at room temperature,the seed vigor would decrease even faster with the increase of storage time,compared with that stored at lower temperature. Different media had a certain effect on seed germination and seedling growth. The results showed that seed vigor from an abundant year was better than that of off year,and would decrease even slower than that of off year with the increase of storage time. The storage at lower temperature was favorable to the maintenance of seed vigor. The reasons resulted in severe danger related to T.sinense seeds are as follows：（1） Small seeds contributed to the spread and dispersal of species,was not beneficial to the survival of seed and seedling. （2） Perennial low temperature was not suitable for seed germination and the formation of a seedling pattern; （3） Perennial moist environment was not suitable for seed living through cold period safely.