休眠解除过程中紫楠种子生理生化特征的变化

【目的】探究紫楠(Phoebe sheareri)种子层积过程中营养物质、酶活性和内源激素的动态变化，揭示种子解除休眠过程中的内在生理机制，为其休眠解除与促进萌发提供理论依据。【方法】以新鲜饱满的紫楠种子为试验材料，采用低温和变温层积处理，测定层积过程中的生理生化指标。【结果】层积处理能解除紫楠种子休眠，低温和变温层积处理的发芽率分别为85.83%、72.75%。紫楠种子中初始淀粉含量为467.88 mg/g,在层积过程中逐渐下降。可溶性糖、可溶性蛋白和粗脂肪均被不同程度地分解。淀粉酶、酸性磷酸酶(APA)和过氧化物酶(POD)活性均不断增强。在整个层积过程中生长素(IAA)、异戊烯基腺苷(IPA)、赤霉素(GA₃)含量不断增加，脱落酸(ABA)含量逐渐减少，IAA/ABA(质量比，下同)、IPA/ABA、GA₃/ABA不断增大。【结论】紫楠种子是中度休眠的种子，低温层积是加快紫楠种子萌发的较好方式。紫楠种子最主要的贮藏物质为淀粉，营养物质的转化与内源激素的协调作用均对紫楠种子休眠的解除起重要作用。

Study on the physiological and biochemical changes of Phoebe sheareri seed during its dormancy breaking

【Objective】 In this study, experiments were carried out to explore the dynamic changes of nutrient contents, enzyme activities and endogenous hormones during the seed stratification of Phoebe sheareri. Additionally, this study was conducted to reveal the internal physiological mechanisms involved in seed dormancy and provide a theoretical basis for its dormancy release and germination. 【Method】 Fresh and full seeds of P. sheareri were treated with gibberellin and stratification was conducted; the physiological indicators during stratification were also determined. 【Result】 The seed dormancy of P. sheareri was relieved by stratification for 63 days. The germination rate of low temperature and variable temperature stratification was 85.83% and 72.75%, respectively. The initial starch content was 467.88 mg/g and decreased gradually during stratification. Soluble sugar, soluble protein and crude fat were decomposed to varying degrees. Under the two kinds of stratification treatments, the soluble sugar content in the seeds of P. sheareri changed greatly, from decreasing to increasing, and then decreasing again. The soluble protein content in P. sheareri seeds increased initially and then decreased under two stratification treatments. On the whole, the crude fat content in the seeds of P. sheareri showed a gradually decreasing trend under each stratification treatment. The activities of amylase, APA and POD were increased. This indicated that the two stratification treatments could promote the continuous activation of APA and POD activities. What’s more, endogenous hormones such as IAA, IPA, GA₃ and ABA played an important role in the regulation of seed dormancy and germination. During the whole stratification process, the contents of IAA, IPA and GA₃ increased, while the contents of ABA decreased, and the mass ratios of IAA/ABA, IPA/ABA and GA₃/ABA increased. 【Conclusion】 There was medium dormancy in seeds of P. sheareri. Gibberellin and stratification could release dormancy, and cold stratification was better to accelerate seed germination. Starch was the main storage material in the seeds of P. sheareri. The transformation of nutrients and the coordination of endogenous hormones played an important role in the seeds dormancy release.