Dynamics of stomatal water relations during the humidity response: implications of two hypothetical mechanisms
Dynamics of stomatal water relations during the humidity response: implications of two hypothetical mechanisms
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DOI：
10.1046/j.0016-8025.2001.00820.x
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发表时间：
2002-03-01
影响因子：
7.3
通讯作者：
Mott, KA
中科院分区：
文献类型：
--
作者：
Buckley, TN;Mott, KA
两个假设的气孔对湿度的反应机制的可行性进行了评估，通过确定这些机制的理论约束，并通过分析气孔孔径的时间过程中的一个步骤的变化，在湿度。两种假设的机制，使保卫细胞膨压克服表皮的机械优势，是：（1）主动调节保卫细胞渗透压，不需要保卫和表皮细胞之间的水力不平衡，和（2）保卫和表皮细胞之间的实质性的水力阻力，导致它们之间的水力不平衡。数值模拟系统是可能的最近发表的经验之间的关系，气孔开度，保卫细胞膨压和表皮细胞膨压之间的气孔压力，保卫细胞压力，这些数据允许假设的控制变量被推断气孔开度和蒸发的需求，给定的物理假设的特征，无论是假设。我们发现，假设（1）预测，稳态pi（g）是单调相关的蒸腾速率，而假设（2）表明，蒸腾速率和稳态保护表皮细胞水力阻力之间的关系可能是积极的或消极的，而且这种阻力必须在气孔响应湿度的瞬态阶段发生实质性变化。
The feasibility of two hypothetical mechanisms for the stomatal response to humidity was evaluated by identifying theoretical constraints on these mechanisms and by analysing timecourses of stomatal aperture following a step change in humidity. The two hypothetical mechanisms, which allow guard cell turgor pressure to overcome the epidermal mechanical advantage, are: (1) active regulation of guard cell osmotic pressure, requiring no hydraulic disequilibrium between guard and epidermal cells, and (2) a substantial hydraulic resistance between guard and epidermal cells, resulting in hydraulic disequilibrium between them. Numerical simulations of the system are made possible by recently published empirical relationships between guard cell pressure and volume and between stomatal aperture, guard cell turgor pressure, and epidermal cell turgor pressure; these data allow the hypothetical control variables to be inferred from stomatal aperture and evaporative demand, given physical assumptions that characterize either hypothesis. We show that hypothesis (1) predicts that steady-state pi(g) is monotonically related to transpiration rate, whereas hypothesis (2) suggests that the relationship between transpiration rate and the steady-state guard to epidermal cell hydraulic resistance may be either positive or negative, and that this resistance must change substantially during the transient phase of the stomatal response to humidity.