Dormancy release and germination in recalcitrant Aesculus hippocastanum seeds
Treść / Zawartość
The investigation of dormancy release in Aesculus hippocastanum seeds was aimed at estimating the proportion of coat-imposed to embryo dormancy, and studying the growth initiation providing embryo dormancy release. During winter, horse chestnut seeds exhibited 16–17 week-lasting deep dormancy, which predominantly was determined by coat-imposed dormancy. Embryo dormancy lasted for 11–12 weeks of wet cold stratification. Embryo dormancy was weak, even the embryo axes excised from deeply dormant seeds were capable of extending to the size exceeding the axis length in intact seeds at radicle protrusion. Embryo dormancy release manifested itself in gradually increasing growth capacity of both embryo axes and cotyledonary petioles. The growth initiation in horse chestnut seeds occurs only by cell elongation. During growth initiation, a more rapid fresh weight gain was observed in comparison with length increment, thus indicating that accumulation of osmotically active substances and active water uptake by embryo axis cells were ahead of their increasing longitudinal cell wall extensibility. Cell wall loosening appeared to be directly related to embryo dormancy release. The hormonal regulation of embryo dormancy release in horse chestnut seeds is discussed.