内蒙古中东部野生扁蓿豆种子硬实性的研究

扁蓿豆是抗逆性极强的优良牧草,但其种子发芽率低,具有65 %～75 %的硬实。在恒温25℃时发芽率较高,在变温20 ～30℃时发芽率最高,若温度超过30℃或低于15℃时发芽被抑制,但短时间高温处理有利于促进发芽。采用机械或浓硫酸处理,发芽率分别比对照高40.6 %和45.6 %。野生种子的硬实率与采集地气温,特别是与7月份温度有着很高的正相关关系,而且不同产地的种子表现出较大的差异,以赤峰市北部采到的居群硬实率最高,比呼和浩特市采集的居群高9 %。随着储藏年限的推移,种子的硬实率不断下降,发芽率增加,储藏3.5年的种子发芽率达到了67.0 %,表明扁蓿豆种子采集后通过室温储藏可以达到提高发芽率的效果。

Seed Hard-coatedness of Medicago ruthenica Grown in Middle and East Part of Inner Mongolia

Medicago ruthenica (L.) Ledebour is a leguminous pasture, which has excellent wild growth in the cold pasture area of the Middle and East part of Inner Mongolia and also proved to be drought tolerance. However, hard seed rate reached 65%～75% and therefore the germination rate was only 29% in the following year after harvest. Under controlled condition, the highest rate of germination of M. ruthenica was found to be at a constant temperature treatment of 25 ℃ and at a temperature treatment varying from 20 to 30℃. The germination was low at or below 15℃ while no germination occurred at 30℃ or above. The germination rate of M. ruthenica seeds was increased significantly with the time of storage. The germination rate increased up to 67% when the seeds were stored for three and half years. The germination rate of M. ruthenica seeds collected from different areas showed the highest positive correlation (r=0.816* *) with the temperature during July. It is thought that the proportion of hard seeds in M. ruthenica seeds is related to the temperature during the period of seed maturation. It is suggested that the high percentage of hard seeds in M. ruthenica is a mechanism of survival and existence under severe climatic conditions.