【作者】 张鹏；

【导师】 沈海龙；

【作者基本信息】 东北林业大学 ， 森林培育， 2008， 博士

【摘要】 休眠与萌发是种子生活史中两个极为重要的阶段,研究种子休眠与萌发的调控技术措施及其内在机制,能使我们更好地认识和利用种子的生理生态特性,科学地指导育苗生产实践。水曲柳（Fraxinus mandshurica Rupr.）是我国东北林区重要的珍贵阔叶用材树种,主要以种子繁殖。本文通过对水曲柳种子发育过程中、层积处理过程中、自然埋藏过程中以及解除休眠后的萌发过程中的生理生态特性进行研究,探讨了在不同发育阶段水曲柳种子的休眠与萌发特性及其调控技术,为制定实用、经济、快速、有效的解除水曲柳种子休眠、促进萌发的技术措施提供理论依据和技术参考。主要研究结论如下:（1）在水曲柳种子发育至成熟过程中,种子中的ABA含量、抑制物质活性和种子胚的离体萌发能力均呈现波动状态,种子在发育至成熟过程中的休眠程度存在变化。开花后110-120 d左右水曲柳种子基本上达到了形态成熟状态,在此后的时间采集种子经层积处理后可以萌发,因此水曲柳适当提前采种是可行的。提前采集的水曲柳种子经暖温（20℃）16周+低温（5℃）12周层积处理破除休眠的效果较好,发育阶段相对早的时期所采种子越需要较长的暖温层积时间来完成胚的发育,适当延长暖温层积时间对于提高种子萌发率效果明显。（2）在水曲柳种子层积处理破除休眠过程中,果皮具有阻碍作用,去果皮处理可以明显促进层积处理过程中种胚的发育,显著提高层积处理后种子的萌发率。流水冲洗处理促进了层积过程中水曲柳种胚的发育,提高了种子萌发率。层积处理前种子进行流水冲洗96 h可以获得较好的催芽效果。层积处理前应用适当的外源激素处理水曲柳种子会取得很好的效果。GA₃在100 mg/L浓度时对提高种子萌发率有一定的效果,而BA则在1 mg/L浓度时对种胚的发育和种子萌发均有明显的促进作用。（3）水曲柳种子层积处理时的暖温层积温度以15℃为好,在此温度下对种子胚发育和种子的萌发有利。采用沙层积时,暖温3个月+低温3个月组合可以获得较好的层积处理效果。采用裸层积处理水曲柳种子是完全可行的,暖温3个月+低温3个月组合条件下裸层积处理水曲柳种子的效果较好,裸层积时种子含水率以45%-50%为宜。（4）水曲柳新种子进行经夏越冬播种是不可行的。而成熟种子经夏越冬播种可以出苗,播种时间宜选在9月之前进行,播种时间晚种子不能充分解除休眠。如果在5-6月份播种则应注意及时灌溉。成熟种子采用经夏越冬播种的出苗率还受种子质量、播种年份自然条件等因素影响。水曲柳种子经夏越冬播种育苗使用适宜的植物生长调节物质处理可以获得较好的场圃发芽效果。综合考虑,使用GA₃处理种子时,以10 mg/L浸种1 d效果最好;使用BA处理种子时,以1 mg/L浸种1 d效果最好;使用KT处理种子,以100 mg/L浸种1 d效果最好。KT浸种对提高水曲柳贮藏种子经夏越冬播种出苗率作用明显,它可以促进经夏越冬播种过程中种胚的生长,同时促进内源激素GA₃、ZT和ABA向有利于种子萌发的方向发展。（5）已解除休眠水曲柳种子变温条件下的萌发比恒温条件的好,种子萌发的适宜变温条件为15℃/10℃,适宜恒温条件是10℃,20℃以上的恒温会诱导种子产生二次休眠。在超过20℃的较高温度下持续较短时间（1 d）后再恢复到适宜的萌发温度下种子发芽受到的影响不大;但在较高温度条件下如果超过3 d再恢复到适宜的萌发温度下则大部分种子会产生二次休眠,以致发芽率下降。在较高温度下萌发过程时,水曲柳种子中的各种内源激素会向利于种子休眠的方向发展,从而使正常萌发的一些代谢过程受到抑制,导致种子不能正常萌发。在适温萌发条件下植物生长调节物质对已解除休眠水曲柳种子的萌发并没有明显的促进作用,但在较高温度条件下,植物生长调节物质能够提高已解除休眠水曲柳种子的萌发率,降低种子产生二次休眠的比例。水曲柳二次休眠种子的胚本身并不存在休眠,导致种子不能萌发的原因是由于胚乳环境的存在。干燥处理和低温处理对于解除水曲柳种子的次生休眠效果不理想,乙烯利1.0 mmol/L处理和GA₄₊₇ 1.O mmol/L处理对于水曲柳种子次生休眠的解除效果较好。水曲柳次生休眠种子经乙烯利处理后,种子中的各种内源激素会向利于种子萌发的方向发展,从而恢复了正常萌发的代谢过程,最终使种子萌发。更多还原

【Abstract】 Dormancy and germination are two important stage in seed life cycle.The study on regulation techniques and its mechanism for seed dormancy and germination let us well understand and use seed ecophysiological characters to guide seedling growing practice. Fraxinus mandshurica Rupr.is an important and valuable hardwood species in Northeast China,and seed propagation is its main propagation method.The ecophysiological characters of seed dormancy and germination of Fraxinus mandshurica during seed development, stratification,natural burying and germination were studied and discussed for the purpose of providing theoretical basis and technique reference to establishment of the functional, economic,fast,and effective methods for breaking seed dormancy and promoting seed germination of Fraxinus mandshurica.The main results were as follows:（1） The ABA content,inhibition activity and embryo germination ability of Fraxinus mandshurica seeds presented fluctuation pattern in different time of seed development till maturity,which is suggested that seed dormancy degree was fluctuated in this process.The seeds of Fraxinus mandshurica reached morphological maturity status at 110 to 120 days after flowering,and the seeds collected during this time could germinate normally after stratification, thereby,seed collection ahead of regulation required schedule for Fraxinus mandshurica is feasible.Stratification at 5℃for 12 weeks following at 20℃for 16 weeks is better for seeds collected ahead of schedule to break dormancy,and the earlier the development time of the collecting seeds,the more warm pretreatment time needed to finish seed embryos growth. Prolonged warm pretreatment for Fraxinus mandshurica seeds collected ahead of schedule had evident effect on improving the subsequent seed germination.（2） In process of Fraxinus mandshurica seed stratification,pericarp acted as an inhibitor, and pericarp removing promoted embryo growth and the subsequent seed germination. Washing also promoted embryo growth and the subsequent seed germination,and the feasible time for washing before seed stratification was 96 hours.Dealing with proper plant growth regulators before seed stratification could get good pretreatment effect.Treating with 100 mg/L GA₃ promoted the subsequent seed germination,but not the embryo growth,whereas treating with 1 mg/L BA promoted not only the embryo growth but also the subsequent seed germination.（3） The better temperature for Fraxinus mandshurica seed warm stratification was 15℃,it was favorable for the embryo growth and seed germination.When seed stratificated in sand or no medium,pretreatment at cold for 3 months following 3 months at warm could get better germination.Naked stratification（without medium） for Fraxinus mandshurica seed is feasible, and the seed moisture content within 45%-50%in cold pretreatment stage was better for seed germination.（4） Seeds sowing in pre-year summer for Fraxinus mandshurica fresh seed is not feasible, but the stored seeds could emerge by this method.The sowing time sould be arranged berfor September,and seed dormancy would not be broken if the sowing time was too late.If seeds sowed in May or June,the sowing bed should be irrigated in time.The emergence rate of Fraxinus mandshurica seed sowing in pre-year summer was also effected by seed quality, climate of the sowing year and other factors.Dealing with proper plant growth regulators before seed sowing in pre-year summer had good effect on seed germination.Treating with 10 mg/L GA₃,1 mg/L BA or 100 mg/L KT for one day could get better germination results.The action of KT was investigated,and the results indicated that KT treatment promoted embryo growth and endogenous hormone（GA₃,ZT,and ABA）changing to the status in favor of seed germination.（5） Statified Fraxinus mandshurica seed germinated better under alternating termperature regimes than that under constant temperature regimes.The optimum alternating and constant temperature regimes were 15℃/10℃and 10℃respectively,and a constant regime over 20℃would induce secondary dormancy.Incubation at this temperature for at least 3 days inhibited seed germination over the temperature regime 15℃/10℃,temperature previously suitable for germination.When germination under high temperature,endogenous hormone of statified seeds changed to the status in favor of seed dormancy,thereby some metabolization processes for germination were inhibited,and seed could not germinate.When germination under suitable temperature,dealing with plant growth regulators had no obvious effect on seed germination.But,when germination under high temperature,dealing with plant growth regulators promoted the subsequent seed germination and the decrease in germination level was delayed.The reason for secodary dorancy were investigatied,and the results suggested that the embryo was not dormant,but the endosperm played an important role in the induction of secondary dormancy at high temperature.Desccation and cold treatment were not good methods for secondary dormancy releasing of Fraxinus mandshurica seed.However,dealing with 1.0 mmol/L ethephon or GA₄₊₇ released seed dromancy preferably.The action of ethephon in releasing secondary dormancy was that it promoted endogenous hormone changing to the status in favor of seed germination,and recovered metabolization processes for germination, ultimately the seed germinated.更多还原