青钱柳种子的种皮构造及其对透水性的影响

The Seed Coat Structure of Cyclocarya paliurus and Its Effects on Water Permeability

通过青钱柳种子的形态解剖、种皮结构的电镜扫描、种皮的透水性等试验,对青钱柳种皮构造与种子休眠关系进行研究,以探讨青钱柳种子的休眠原因。结果表明,青钱柳种子种皮有3层,外种皮表面角质化,中种皮木栓质,内种皮木质而坚硬,这在一定程度上阻碍了胚与外界的水汽交换,影响种子的吸胀和萌发。种皮的透水性试验结果表明,浓硫酸处理后,种子能很快吸水膨胀。种子各部分的含水量测定结果表明,青钱柳完整种皮种子的胚能吸收到部分水分,因此,种皮的透水性可能不是引起青钱柳种子休眠的最主要因素。但是,青钱柳种子的这种种皮结构可能对胚的萌发特别是胚根的生长和伸长会产生严重的机械阻力。

In order to discuss the dormancy characteristics of Cyclocarya paliurus seeds, the seed coat structure of this tree and its effects on the water permeability were studied. The results showed that in. the seed coat of C. paliurus consists of three layers, i. e. , external, middle, and inner seed coat. The epidermis of external seed coat is cutinized, and the middle seed coat is phellem, and the inner seed coat is lignified and hard. All these characteristics show a hindrance and permeability barrier in the seed coat of C. paliurus, preventing the water and gas exchanging and resulting in blocking germination. Compared to the seeds in control, the seeds treated by concentrated sulphuric acid absorbed more water and the speed of water permeation was more quickly. However, the embryos of untreated seeds also absorbed some water in the water absorption experiment.Therefore, the permeability of the seed coat to water may not be a main reason to cause the seed dormancy of C. paliurus. The mechanical restraint of seed coat to radicel growing may be the main reasons.