小麦铭贤169休眠解除期间种子结构与主要成分的变化

为探究小麦种子休眠解除期间的成分变化对发芽率的影响，了解种子休眠解除机制，以铭贤169为材料，在收获后不同储藏时间(间隔20 d)取样，通过显微设备观察了种子后熟期间的结构变化，测定了相关生理指标和成分，以探究铭贤169种子休眠性原因。结果表明，铭贤169种子休眠解除过程中，种皮细胞结构、组织结构、淀粉粒结构、蛋白基质等均发生变化，淀粉含量、粒径、糊化特性、热稳定性随贮藏时间延长变化显著。铭贤169的离体胚在花后25 d就具有发芽能力，但种子在花后35 d仍处于休眠。收获后熟期间，种胚活性、种子吸水率、含水量、淀粉含量、淀粉糊化谷值粘度和峰值时间、热稳定性逐步上升，与发芽率正相关。A型淀粉粒表面破损，淀粉粒与蛋白质结合紧密，种皮结构松散；淀粉粒径、淀粉酶活性、可溶性糖含量和沉降值减小；面筋和粗蛋白含量变化不大。推测铭贤169种子的休眠性与种子母体成分有关，休眠解除期间发芽率变化受种皮结构、淀粉的分解程度、淀粉粒与蛋白质的结合方式、可溶性糖含量、淀粉含量和性质以及淀粉酶活性等因素影响。

Changes of Seed Structure and Major Components during Dormancy Release in Wheat Mingxian 169

In order to investigate the effect of compositional changes on germination rate during the dormancy release of wheat seeds and study the mechanism of seed dormancy release, Mingxian 169 was used as material to investigate the genetic causes of dormancy of Mingxian 169 seeds and comparatively analyze the changes of seed structure and composition during the post-ripening period, by using microscopic structure observation and physiological index measurement at different storage time points(20 d interval) after harvest, in order to provide a reference for revealing the germination resistance mechanism of wheat pre-harvest sprouting. The results showed that the seed coat cell structure, tissue structure, starch grain structure and protein matrix of wheat seeds changed during the process of dormancy release, and the starch content, grain size, pasting characteristics and thermal stability changed significantly during the measurement period. the embryos of Mingxian 169 had the ability to germinate at 25 d after flowering, but the seeds remained dormant at 35 d after flowering. After harvest, the dormancy release time was prolonged, and the seed embryo activity, seed water absorption, water content, starch content, starch gelatinization peak viscosity, peak time and thermal stability gradually increased, which was positively correlated with germination rate. The surface of type A starch granules was damaged; the starch granules were closely combined with protein, and the seed coat structure was loose. Starch particle size, amylase activity, soluble sugar content and sedimentation value decreased. The content of gluten and crude protein changed little. In conclusion, the dormancy acquired by Mingxian 169 seeds is related to the parent seed composition, and that changes in germination rate during dormancy release are influenced by the seed coat structure, the degree of starch breakdown, the binding mode between starch particles and protein, soluble sugar content, starch content and properties, and amylase activity.