酢浆草种子弹力传播机制初探

The Seeds Elastic Transmission Mechanism in Oxalis corniculata L.

酢浆草(Oxalis corniculata L.)在幼嫩和成熟弹射后两个生理时期果实组织切片,并观察不同生理时期果实特征和野外测量酢浆草种子梯度弹射距离。结果表明:酢浆草的果皮在果实成熟阶段背缝线处已裂开,对种子的弹力传播作用不大。假种皮主要由泡状细胞组成,成熟过程中泡状细胞失水收缩严重,细胞间收缩不平衡产生扭转力并随着成熟过程逐渐积聚,当超过临界点后在种子尖端处裂开并翻卷,将种子以反弹形式斜抛出去。假种皮是酢浆草种子弹力传播的关键结构。种子质量与弹射关系图表明弹射距离越远,种子质量越大,且干重时比鲜重时关系更加明显,种子密度分布随传播距离增大先增后减。

The fruits of Oxalis corniculata L. were made into tissue sections respectively in their tender and mature period with paraffin method and they were observed to make the features in different physiological period. Besides, the ejecting distance was also measured. The results are as follows: The dorsal suture has been dehisced in ripening stage, so it scarcely contributes to seed transmis-sion by ejecting. Yet, aril is made up with bulliform cell, due to bulliform cell lost water severely in ripe period, tension is produced and accumulated gradually because of intercellular contracting balance. Also, the tip of seed would dehisce and turn up and the seeds would be tossed out by re-bounding when the tension beyond its critical point. Overall, aril is critical structure in seed transmission by rebounding. As chart shows ejecting distance is in direct proportion to fresh seed quality and the relationship is more obvious when dry seed is used. In addition, the density of seeds first increased and then decreased with increase of spreading distance.