Key message

Hydration cycles promote embryo physiological changes, favoring overcoming dormancy in Butia capitata seed banks.

Abstract

Dormant seeds can spend many years in soil seed banks while subject to successive hydration and dehydration cycles (HC). Our knowledge concerning the effects of HC on seed survival and on overcoming dormancy is still limited, especially among tropical species. We sought to evaluate structural and physiological aspects of the diaspores (pyrenes: seeds enclosed by the endocarp) of the neotropical palm Butia capitata submitted to HC (in association with thermal regimes) under laboratory conditions and in a simulated soil seed bank. Biometric, anatomical, histochemical, biomechanical (the resistance of restrictive structures to embryo growth), and physiological (viability, the potential for in vitro embryo elongation, germination, and endo-β-mannanase activity) evaluations were performed. HC, in association with thermal regime variations, positively affect the growth potential of the embryos, which is related to an increase in their water absorption capacity, increased cell division, embryo expansion, and endosperm reserve mobilization. Those changes result in a gradual decrease in dormancy intensity, allowing a gradual exit from the soil seed bank through germination. Diaspores of B. capitata present morphophysiological dormancy of a particular type that is characterized by restricted embryo growth inside the seed before germination, low levels of endosperm reserve mobilization, and the gradual overcoming of dormancy over several years. The ability to form soil seed banks is an important adaptive strategy when faced with a seasonal environment with irregular rainfall in which the species occurs.

中文翻译：

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水化循环和克服 Butia capitalata (Arecaceae) 水散石中的休眠

关键信息

水化循环促进胚胎生理变化，有利于克服Butia capita种子库中的休眠。

抽象的

休眠种子可以在土壤种子库中保存多年，同时还要经历连续的水化和脱水循环 (HC)。我们关于 HC 对种子存活和克服休眠的影响的知识仍然有限，尤其是在热带物种中。我们试图评估新热带棕榈布提亚的水硬铝石（芘：被内果皮包裹的种子）的结构和生理方面在实验室条件和模拟土壤种子库中提交给 HC（与热制度相关）。进行了生物统计学、解剖学、组织化学、生物力学（限制性结构对胚胎生长的抵抗力）和生理学（活力、体外胚胎伸长、发芽和内切-β-甘露聚糖酶活性的潜力）评估。HC 与热状态变化相关联，对胚胎的生长潜力产生积极影响，这与它们的吸水能力增加、细胞分裂增加、胚胎膨胀和胚乳储备动员有关。这些变化导致休眠强度逐渐降低，允许通过发芽逐渐离开土壤种子库。B.capitata 的离散孢子目前一种特殊类型的形态生理休眠，其特征是在萌发前种子内胚胎生长受限，胚乳储备动员水平低，以及几年内逐渐克服休眠。当面临物种出现的不规则降雨的季节性环境时，形成土壤种子库的能力是一种重要的适应策略。