【作者】 杨万霞；

【导师】 方升佐；

【作者基本信息】 南京林业大学 ， 森林培育学， 2004， 硕士

【摘要】 青钱柳种子属于综合性深休眠类型，在自然条件下，需要经过隔年甚至2年才能萌发，本文通过青钱柳种子的形态解剖、种皮的扫描电镜结构、种皮的透水性及种皮醇提液的生物测定等试验，探讨了青钱柳种子的休眠原因。同时采用浓硫酸腐蚀、GA₃浸种、变温层积和自然层积两组处理，寻找快速解除青钱柳种子休眠的方法，并测定层积过程中的淀粉、可溶性糖、激素的含量和淀粉酶活性的变化，初步了解青钱柳种子的萌发生理。实验结果表明： 青钱柳种子种皮有三层，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气交换，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，种皮机械结构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对胚的萌发特别是胚根的生长和伸长起到了严重的机械阻力。 通过青钱柳种子种皮醇提液的生物测定，青钱柳种子种皮浸提液中含有某些抑制物质，这些抑制物质对白菜籽的发芽率、幼苗的高生长、根长生长及种子活力都有抑制作用，在浓度较高时尤为明显。这说明在青钱柳种子的种皮内积累了大量的抑制物质，这些抑制物质能抑制种子萌发，使幼胚被迫进入深度休眠状态。 在青钱柳种子综合处理解除休眠的过程中，随着层积时间的增长，其脱落酸（ABA）的含量逐渐减少，而赤霉素（GA）、生长素（IAA）、细胞分裂素（CTK）的含量则逐渐增加。赤霉素（GA）／脱落酸（ABA）、生长素（IAA）／脱落酸（ABA）和细胞分裂素（CTK）／脱落酸（ABA）的比值总体上也呈现出增加的趋势。本文实验结果进一步证实了赤霉素（GA）是种子萌发的促进物质。同时，生长素（IAA）、细胞分裂素（CTK）在解除种子休眠萌发的过程中也起到一定的促进作用。在自然层积过程中，随着层积时间的增长，淀粉酶活性逐渐增加，淀粉分解加速，含量降低，种子内可溶性糖含量不断增加，层积的种子各个阶段可溶性糖含量都比未层积的要高。更多还原

【Abstract】 Cyclocarya paliurus seeds germinate on the second year or the third year in nature, belonging to a type of comprehensive deep dormancy. In this study the dormancy characteristics of Cyclocarya paliurus seeds are studied through experiments such as morphological dissecting of the seeds, the seeds coats microstructure under the scanning electron microscope, the water absorption of seeds coats and the biotic measurement of the methanol extract of Cyclocarya paliurus seeds coats. The quick dormancy-breaking techniques of Cyclocarya paliurus seeds are studied through two kinds of treatments. One treatment is soaking the seeds in concentrated sulphuric acid first, soaking the seeds in GAs 48 hours, and then stratifying seeds under different temperatures. The other treatment is stratifying seeds under natural temperatures. And during the stratification treatment, the content of starch , the content of soluble sugar, the content of endogenous hormones and the activity of the amylase in the seeds are measured to find out the germination physiology of Cyclocarya paliurus seeds. The results are as followings.Three layers are found in the seed coat of Cyclocarya paliurus under the scanning electron microscope: external seed coat, mid seed coat, and inner seed coat. The epidermis of external seed coat is cutinized, and the mid seed coat is phellem, and the inner seed coat is lignified and hard. All these characteristics show a big hindrance and permeability barrier in the seed coat of Cyclocarya paliurus, preventing the water and gas from exchanging and resulting in blocking the water absorbing and germinating of the seed. And the result of water absorption of seeds coats show that seeds which are treated by concentrated sulphuric acid absorb water more quickly than the control seed do. The water consent of the seeds shows that the embryos of untreated seeds also absorbed some water in the water absorption experiment. So the mechanical restraint of the seed coat which restrain radicel growing is one of the main reasons to cause the seed dormancy of Cyclocarya paliurus.The biotic measurement results of the methanol extract of Cyclocarya paliurus seeds coat show that the methanol extract contains some germination-restrauiing substance which could reduce cabbage seed germination and simplified vigor index(SVI),and suppress seedling and root growth, especially at high concentration treatment.. This result shows that some germination-restraining substances in Cyclocarya paliurus seeds coat could result in the dormancy of the young embryos.During seeds stratification under different temperatures to break dormancy, the content of abscisic acid (ABA) in the Cyclocarya paliurus seeds reduces gradually, but the contents ofgibberellic acid (GA),indole-3-acetic acid (IAA) and cytokinin (CTK) increase at the same time, and the ratios of gibberellic acid (GA)/ abscisic acid (ABA), indole-3-acetic acid (IAA)/ abscisic acid (ABA), cytokinin (CTK)/ abscisic acid (ABA) increase ultimately. The results of the experiments make sure that GA promotes seeds germination and that indole-3-acetic acid (IAA) and cytokinin (CTK) affect the seeds germination too. During seeds stratification under nature temperatures, the total activity of the amylase increases, amylolysis accelerates, the content of starch reduces, the content of soluble sugar increases continuously, and the content of soluble sugar in the stratified seeds is more than in the control seeds.更多还原