Capacitance Influences on the Water Relations of Desert Perennials

水是沙漠生长和生存的关键 植物 它可以储存在芽，这是特别 明显的肉质植物，如龙舌兰沙漠（常见的 沙漠龙舌兰）和Ferocactus acanthodes（桶仙人掌）。 这种储存的水的内部再分配可以影响水 在蒸腾流中流动，从土壤到 根、茎和叶，并导致非稳态 （瞬时）效应。 如此短暂的影响。可 考虑在电路中加入电容器 蒸腾流的类似物， 注意植物，虽然非稳态实际上是 这是自然条件下植物的规律，而不是例外。 多肉植物如A. deserti和F.棘头蚴 景天科酸代谢，其中发生CO2吸收 主要是在夜间，当温度较低，因此， 从植物到空气中的水分损失较少。 在晚上导致苹果酸的形成， 渗透压大幅度增加。 这种渗透压的增加 压力通过渗透作用影响水的运动， 以前没有被包括在电路中 植物水分关系的类似物。 将采用一种新方法 允许结合这种非线性因素。 新的成像 医学研究中开发的方法也将用于 观察根在土壤中的位置。 使用电路模拟，水运动和水 将用计算机模拟不同位置的电位 为解决电路问题而开发的程序。 每个组件 (such作为一片叶子）在蒸腾流将被分配一个 电容，该电容将通过存储电阻连接 血管组织的主要轴向流动。 领域 对沙漠多肉植物的测量也将被用来解释 促进沙漠多肉植物对水分胁迫的关键适应 和水的使用。 将数据合成到动态模型中应该 提高我们对细胞特性的定量理解 以及电容和渗透压的重要性 维持有利于植物生存的水势， 特别是当他们暴露在自然或人为的环境中时， 改变了环境条件。

Water is the key to the growth and survival of desert plants. It can be stored in the shoots, which is especially apparent for succulent plants such as Agave deserti (the common desert agave) and Ferocactus acanthodes (a barrel cactus). Internal redistribution of such stored water can influence water flow in the transpiration stream, the pathway from the soil to the root, stem, and leaves, and lead to non-steady state (transient) effects. Such transient effects. which can be considered by incorporating capacitors in electrical circuit analogs of the transpiration stream, have received little attention for plants, although the non-steady state is actually the rule, not the exception, for plants under natural conditions. Succulent plants such as A. deserti and F. acanthodes employ Crassulacean acid metabolism, where CO2 uptake occurs predominantly at night when temperatures are lower and hence water loss from the plant to the air is less. The CO2 taken up at night leads to the formation of malate, with a consequent large increase in osmotic pressure. This increase in osmotic pressure influences water movement by osmosis, a complication that has previously not been included in electrical circuit analogs for plant water relations. A new method will be employed that allows incorporation of this non-linear factor. New imaging methods developed in medical research will also be used to observe root location in the soil. Using an electric circuit analog, water movement and water potential will be simulated at various locations with computer programs developed to solve electrical circuits. Each component (such as a leaf) in the transpiration stream will be assigned a capacitance, which will be connected through a storage resistance to the main axial flow of the vascular tissue. Field measurements of desert succulents will also be made to interpret further the key adaptations of desert succulents to water stress and water use. Synthesizing the data into a dynamic model should enhance our quantitative understanding of the cellular properties of plants and the importance of capacitance and osmotic pressure in maintaining water potentials favorable for plant survival in the field, especially when they are exposed to natural or man- made changes in environmental conditions.