光照和温度对望天树种子萌发的影响

Influence of Light and Temperature on the Germination of Shorea wantianshuea (Dipterocarpaceae) Seeds

在实验室内人工气候箱控制的条件下,研究了我国重要珍稀濒危植物望天树(Shoreawantianshuea,龙脑香科(Dipterocarpaceae))种子萌发对持续光照、14小时光照/10小时黑暗周期性光照的反应;同时研究了望天树种子的萌发对不同温度的反应和低温贮藏对种子活力的影响。结果表明,不论是持续光照还是周期性光照都不能提高望天树种子的萌发率,相反,持续光照和周期性光照都不同程度降低了种子萌发率。光照能通过加速或延迟种子萌发的进程、或改变幼苗活力指数和萌发指数而影响种子萌发的质量;持续光照延迟种子萌发的进程,而周期性光照加快种子萌发的进程。30℃是种子的最适萌发温度,虽然15℃和5℃的相对低温对幼苗活力指数影响不大,但大大延迟了种子萌发进程,并提高萌发率。望天树种子不能耐受5℃低温贮藏,但具有在15℃下短期贮藏的潜力和一定程度的生理性休眠。

Under consecutive irradiance and 14 h / 10 h light-darkness cycle, the effects of different gradients of irradiance on seed germination of Shorea wantianshuea, an endangered and rare species of dipterocarpaceae in Xishuangbanna, Yunnan Province, were studied. Also, the effects of different temperatures on seed germination and storage were examined. Neither consecutive irradiance treatments nor periodic ones could improve the germination percentage （GP）. The average GPs of the two groups of treatments reduced from 94.7% （control） to 86.3% and 86.7% respectively. Moreover, consecutive irradiances led to an increase in coefficient of rate of germination （CRG）, which indicates the delay of the course of germination. Although a decrease in GP was observed, periodic irradiance treatments showed the acceleration of germination course and increase of germination index （GI）. The temperature of 30℃ was the optimum germination temperature for S. wantianshuea seeds. The relatively low temperatures of 15 ℃ and 5 ℃ greatly delayed the course of seed germination. Compared with 30℃, these two ＂low temperatures＂ treatments showed significant decreases in GI. The valures of GI were 38.9, 6.3 and 1.1 at 30℃, 15 ℃ and 5 ℃ respectively. Shorea wantianshuea seeds could not be stored at 5 ℃, but it had short-period storage potential at 15 ℃.