Water relations of germination in the recalcitrant seeds of Quercus robur L.
Water relations of germination in the recalcitrant seeds of Quercus robur L.
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DOI：
10.1017/s096025850000235x
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发表时间：
1994-09-01
影响因子：
2.1
通讯作者：
Clay, H. A.
中科院分区：
文献类型：
--
作者：
Finch-Savage, W. E.;Clay, H. A.
夏栎果实对干燥敏感，在高水分含量（约 48%）时会从植物中脱落。在过早收获的未成熟果实和自然脱落的成熟果实的发芽期间每隔一段时间进行水关系测量。在这两种收获的果实中，果皮和种皮通过为胚根的出现提供物理屏障并限制吸胀率来延迟发芽。尽管未成熟的果实可以在没有水的情况下发芽，但在有外部供水的情况下发芽更快。完全成熟的果实需要外部水分的供应，但发芽比未成熟的果实更快。在果皮分裂和随后的未成熟果实发芽之前，发生了显着的生理变化，导致溶质积累，轴尺寸和延伸性增加。这种变化并没有发生在完全成熟的果实中，但是两次收获的果实都吸收了水分，并且果皮的分裂似乎是由于胚胎尺寸和组织压力的增加造成的。在没有外部供水的情况下，未成熟的果实在发芽前的分裂是最小的。这表明，当果皮分裂时，轴上的 psi(p) 降低幅度大于子叶，因为子叶的扩张能力更强。这将产生一个 psi(w) 梯度，驱动水从子叶流向轴，从而允许胚根持续生长以利于发芽。
Quercus robur L. fruits are desiccation sensitive and shed from the plant at high moisture content (c. 48%). Water relations measurements were taken at intervals during the germination of prematurely-harvested immature fruits and naturally-shed mature fruits. In fruits from both harvests the pericarp and seed coat delayed germination by providing physical barriers to emergence of the radicle and by restricting the rate of imbibition. Although immature fruits could germinate in the absence of water they germinated more rapidly in the presence of an external water supply. The fully-mature fruit required a supply of external water, but germination was more rapid than in immature fruits. Substantial physiological changes, resulting in the accumulation of solutes, and increased axis size and extensibility occurred before splitting of the pericarp and subsequent germination of immature fruits. Such changes did not occur in fully-mature fruits, but fruits from both harvests imbibed water and splitting of the pericarp appeared to result from increased embryo size and tissue pressure. Splitting was minimal prior to germination in immature fruits without an external water supply. It is suggested that the resulting reduction in psi(p) when the pericarp splits was greater in the axis than in the cotyledons because of its greater capacity for expansion. This would create a psi(w) gradient driving water flow to the axis from the cotyledons allowing continued radicle growth for germination.