【摘要】 刺楸种子休眠属于复杂的形态-生理休眠类型。休眠期6个月以上。种子成熟时,种胚尚未分化完全,需先温暖(15—20℃)层积3个月,以完成胚的生长与发育,然后转入低温(0—5℃)层积2—3个月,种子才能解除休眠,即种胚必须经所谓的形态后熟和生理后熟两个不同的阶段,种子才能获得萌发能力 实验表明,层积后熟过程中,ABA和香豆素有相似的变化趋势;随温暖层积的进行,抑制物质水平迅速减少,但ABA含量下降的速度比香豆素快。种子完成形态后熟时,ABA含量降到最低水中,而香豆素在种子完成形态后熟后,再转入低温处理1个月时,才降至最低水平。对比测定持续低温和先低温后温暖处理条件下,ABA和香豆素的含量表明,持续低温下,两类抑制物质含量无明显的下降趋势;先低温后温暖处理过程中,ABA在先期低温处理基本维持较恒定水平,转入温暖处理后,ABA水平才开始减少,而香豆素表现不十分明显。 种子不同部位抑制物质的变化同全种子抑制物质变化情况相似,但层积过程中,ABA和香豆素均有从种子外被(果皮和种皮)向种子内部(胚与胚乳)转运现象发生。 实验证明刺楸种子中同时存在两类抑制物质(ABA和香豆素),是种子休眠的最主要原因,抑制物质对刺楸种子的作用主要限于对胚分化与生长。更多还原

【Abstract】 The study showed that the seed embryos were under differentiating and deep dormant when the seeds matured. In order to break the seed dormancy, first, the seeds must be stratified at warm temperature(15—20℃) for about three months, then at low temperature(0—5℃)for over two months. Kalopanax seeds being to morphx morphological physiological dormancy.Both ABA and coumarin were determined by HPLC and bioassay during stratification of the seeds. The condition for stratification were as follows : (1) continuous warm temperature, (2)continuous chiiling(0—5℃), (3) first warm then chilling, (4) chilling then warm. It was found that ABA and coumarin levels decreased rapidly as seeds were stratified at 15—20℃, but ABA contents reduced faster then coum arins. After three months stratification, the differentiation of the seed embryo completed. ABA reached the lowest level while eoumarin content was lowest following warm treatment three months and one month low temperature stratification. In addition, ABA and coumarin maintained constant during 0—5℃ stratification at which the seed did not differentiate and the seed dormancy has not broken. If warm treatment was carried out after 0—5℃ stratification, ABA level decreased, coumarins changed unobviously, the seed embryos began to differentiate gradually.The changes of inhibitors in the periearp, seed coat and embryo (with endosperm) were found to be similar to the all-seed during stratification. It was found that ABA and coumarin can transport from outer-cover (pericarp and seed coat) to inner(endosperm and embryo).The study suggested that ABA and coumarin existing in every part of the seed are an important cause of the seed dormancy. The effects of inhibitors on seed dormancy mainly limit embryo differentiation and growth. It seems that ABA and coumarin may be responsible for the morphological after-ripenning(warm treatment) of the embryo, but the inhibitors have a little something with the physiological after-ripenning(chilling).The author also give the views on the debate about ABA effects in seed dormancy.更多还原