Embryo position of Castanopsis sclerophylla (Fagaceae) seeds with recalcitrant storage behavior differs from Quercus genus but response to desiccation shows no difference

Abstract

In many but not all recalcitrant Quercus seeds, water loss during drying only occurs through the scar. Consequently, the embryo axis sitting on the opposite side of the scar is well protected from desiccation. However, whether such a mechanism is common throughout Fagaceae species is unexplored. Similarly, little is known about the desiccation response of other Fagaceae genera. Germination and desiccation tolerance of Castanopsis sclerophylla (Lindl. & Paxton) Schottky (Fagaceae) were studied by drying the seeds with silica gel. Fresh seeds had a moisture content (MC) of 36% and germinated to 92.5% when incubated at 15/20 °C. Drying seeds to 22.5% and 20.7% MC decreased germination to 27% and 5%, respectively, indicating that seeds are recalcitrant. X-ray computed tomography and photomicrographs showed that the embryo axis of C. sclerophylla is located just below the scar. Regardless of drying occurring either through only the scar or the whole pericarp, embryo drying was deemed unavoidable. Nevertheless, germination percentage during drying showed exceptional similarities with the other Fagaceae species.