Seeds of Papilionoideae (Leguminosae) species lose water after dispersal, increasing the proportion of water-impermeable seeds (physical dormancy, PY). However, changes in testa structure during this process remain unknown. The present study investigated how variation in relative humidity (RH) during the post-dispersion period affects the proportion of seeds of Erythrina speciosa with PY. Seeds from two populations were stored in drier (40% RH) and wetter (80% RH) environments and periodically subjected to physiological analysis (seed water content, imbibition and germination) and structural analysis of the testa (light and scanning electron microscopy). Drier storage resulted in seed dehydration, increasing the proportion of water-impermeable seeds and closure of cracks in the mucilaginous stratum. In contrast, wetter storage led to an increase in seed water content, a decrease in the proportion of seeds with PY, and the formation of cracks. As a result of variation in environmental humidity, we conclude that changes occur in the mucilaginous stratum of seeds, altering water loss and, consequently, the proportion of seeds with PY. Environments with low humidity cause a decrease in seed water content, the closing of cracks in the mucilaginous stratum, and, consequently, an increase in the proportion of water-impermeable seeds. On the other hand, a high RH environment increases the seed water content and the formation of superficial cracks, through which water enters during imbibition, causing a decrease in the proportion of seeds with PY.

中文翻译：

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分散后湿度条件改变刺桐种皮表面和物理休眠种子的比例

Papilioideae (Leguminosae) 物种的种子在散布后会失水，增加了不透水种子的比例（物理休眠，PY）。然而，在这个过程中睾丸结构的变化仍然未知。本研究调查了散布后相对湿度 (RH) 的变化如何影响种子的比例。刺桐与 PY。来自两个种群的种子储存在较干燥（40% RH）和较潮湿（80% RH）的环境中，并定期进行生理分析（种子含水量、吸水和发芽）和种皮的结构分析（光学和扫描电子显微镜）。较干燥的储存导致种子脱水，增加了不透水种子的比例和粘液层裂缝的闭合。相比之下，较湿的储存导致种子含水量增加，PY 种子比例降低，并形成裂缝。由于环境湿度的变化，我们得出结论，种子的粘液层发生了变化，改变了水分流失，从而改变了带有 PY 的种子的比例。低湿度环境会导致种子含水量减少，粘液层裂缝闭合，因此不透水种子的比例增加。另一方面，高RH环境会增加种子含水量并形成表面裂缝，在吸水过程中水会通过这些裂缝进入，导致带有PY的种子比例下降。