蕨类植物和裸子植物叶光合特性对干旱和复水的响应
首发时间:2017-02-09
摘要:维管束植物从低级到高级的进化历程中,是否形成优化的水分利用策略,是学术界研究的重大命题。本文以两种蕨类植物(荚果蕨、凤丫蕨)和两种裸子植物(水杉、银杏)为对象,分析干旱和复水过程中植物种类间叶水势、光合特性及水分传导的差异,以期对蕨类植物和裸子植物的水分利用策略进行认识。结果表明,干旱和复水过程中,蕨类植物的气孔导度(下同)随叶水势的下降而下降,复水后随叶水势迅速恢复而恢复,即气孔完全依赖于水势的调控,仅具被动控制过程,但裸子植物的气孔导度随叶水势的下降而下降,复水后叶水势的迅速恢复但气孔导度恢复缓慢,即被动控制过程和主动控制过程兼有;干旱胁迫下,蕨类植物维持叶水分传导的能力弱,但复水后叶水分传导速率恢复快,叶水分传导速率水势、气孔导度同步恢复,而裸子植物维持叶水分传导的能力强,复水后叶水分传导速率恢复慢,但恢复后气孔导度仍未恢复;干旱和复水过程中,蕨类水分利用效率低,裸子植物水分利用效率高。结果证实了裸子植物在水分利用方面具有较强的竞争力,从而对代替蕨类植物从水分利用效率方面进行了解释。
关键词: 植物生理生态学 蕨类植物 裸子植物 气孔行为 叶水分传导 水分利用效率
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The adaptation of leaf photosynthetic characteristics to dehydration and rehydration in ferns and gymnosperms
Abstract:The existence of optimized water use strategy in the evolution of vascular plants became a major scientific argument. We examined leaf water potential, photosynthetic traits and leaf hydraulic conductance during the imposition of water stress and the rehydration later for two fern species and two gymnosperms species to investigate the difference of water use efficiency. Two fern species exhibited a passive stomata behavior driven by water potential. The results shows the stomatal conductance of ferns decline with the falling of leaf water potential and a rapid recovery with the rise of leaf water potential during the process of dehydration and rehydration. Two gymnosperms species were found to show a liner depression between stomatal conductance and water potential during water stress, while a hysteresis in the relationship between water potential and stomatal conductance as rewatered plants recovered from water stress. It indicates the passive control and active control both exist in gymnosperm stomata behavior. Leaf hydraulic conductance in two fern species shower a liner relationship with stomatal conductance by an depression in water stress and a rapid recovery in rehydration. Gymnosperms could maintain leaf hydraulic conductance during dehydration and showed a hysteresis during recovery. Leaf hydraulic conductance in two gymnosperms species did not exhibit a liner relationship with stomata; conductance. Gymnosperms showed a higher water use efficiency in both dehydration and rehydration. We reveal the mechanism of ferns replaced by gymnosperms by confirming gymnosperms is more competitive in water utilization.
Keywords: plant ecophysiology ferns gymnosperms stomata behavior stomata behavior water use efficiency
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蕨类植物和裸子植物叶光合特性对干旱和复水的响应
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