准噶尔无叶豆地理种群种子萌发特性

Variation of seed sizes of Eremosparton songoricum geographic populations and germination characteristics

准噶尔无叶豆种子具有明显的地理种群大小变异的现象。对大、小种子在3种光照（持续光照，12／12小时光照／黑暗，全黑暗）、5个温度梯度（10℃，15℃，20℃，25℃，30℃）条件下的最适萌发条件进行研究，结果表明：大、小种子萌发的适宜光照条件均为12／12小时光照／黑暗，在持续黑暗与持续光照条件下的萌发率无显著差异；最适温度范围是20～25℃，大种子在20℃、25℃下的萌发率（〉85％），萌发指数均显著高于相同温度条件下小种子的萌发率（〈35％）和萌发指数。大种子存在种皮硬实所导致的物理性被迫休眠，而小种子除物理性休眠外，可能还存在其他形式的深度生理休眠。准噶尔无叶豆自然状态下萌发率极低（≤3％），经综合分析，认为种子硬实和深度生理休眠可能是自然状态下种子萌发的困难主要因素，而土壤的光照、温度及湿度不存在明显的对种子萌发的限制。

Eremosparton songoricum, a plant species that only occurs in Gurrbantuggut desert of China, is listed in the China Red Data Book as Class 3 national protected plants. The variation of seed sizes of E. songoricum in different geographic populations is obvious. In order to investigate the seed germination features in the different geographic populations, we collect the seeds in the wild population of Cainan station and Kalabulegen in Gurrbantuggut desert, Xinjiang Province in 2005. The germination characteristics of big and small E. songoricum seeds under thee lights and five temperatures conditions were studied. The results showed that the optimal light condition is 12/12 h light/dark and no difference was found between the germination of big and small seeds in light and in darkness. The optimal temperature range for germination was 20 -25 ℃, yielding maximum germination and germination index. Big seeds have physical dormancy and small seeds not only exist physical dormancy but also may have the other physiological dormancy. The germination of E. songoricum seeds in the nature is very low（ ≤3% ）. After analysis, we considered that the hardness of seeds and physiological dormancy are mainly reason for low germination, however, the light, temperature and soil humidity are not the restriction in E. songoricum germination.