Control of seed germination and dormancy is important in seed plant adaptation and evolution. When studying seed dormancy of Quercus species, we observed a substantially delayed shoot emergence following a fast root emergence in Quercus chungii F.P.Metcalf. Since epicotyl physiological dormancy (PD) has not been reported in Quercus section Cyclobalanopsis, we examined seed morphology and germination in Q. chungii and aimed to document epicotyl PD in the seeds. The embryo was fully developed in fresh ripe seeds. The elongating cotyledonary petiole pushed the embryo axis out of the seed during germination, which differed from observations in other Quercus species. Shoots emerged from seeds with developing roots after 3 months of warm stratification (35/25 °C), reaching the highest percentage of shoot emergence in seeds after 5 months. Seeds were recalcitrant and displayed a yet unreported epicotyl PD type, for which we propose the formula C_nd(root) ‒ Cp’’ 2b(shoot). Early emergence and development of the root system in Q. chungii seeds with epicotyl PD appears to be a mechanism to maintain a constant water supply to the shoot during plumule development and emergence. Our documentation of seed germination will provide guidance for the conservation and restoration of this species from seeds.

中文翻译：

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带有伸长的子叶柄的中华栎FPMetcalf顽calc型种子的中间表皮生理休眠

种子发芽和休眠的控制对于种子植物的适应和进化很重要。在研究栎属物种的种子休眠时，我们观察到了中秋栎FPMetcalf的快速根出苗后，芽的出苗时间大大延迟。由于上胚轴生理休眠（PD）尚未在报道栎部青冈，我们检查了种子的形态和萌发Q. chungii和旨在文档上胚轴PD中的种子。胚胎在新鲜成熟的种子中完全发育。子叶柄的伸长在发芽过程中将胚轴从种子中推出，这与其他栎属的观察结果不同物种。3个月的温热分层（35/25°C）后，芽从具有发达根部的种子中萌芽，在5个月后达到种子中最高的嫩芽百分比。种子是顽固的，并表现出尚未报告的上胚轴PD型，为此我们提出了分子式C _nd（根）‒ Cp''2b（芽）。带有表皮基PD的猪笼草种子根系的早期出苗和发育似乎是在幼芽发育和出苗期间保持枝条恒定水供应的一种机制。我们的种子发芽文献将为从种子中保护和恢复该物种提供指导。