Homeostasis in Plants | 植物的稳态调节

📚 Homeostasis in Plants | 植物的稳态调节

Homeostasis in plants may seem less obvious than in mammals, but plants continuously monitor and adjust their internal conditions. This article explains how plants regulate water potential, ion concentrations, gas exchange, pH and temperature, with a strong focus on stomatal behaviour and the role of abscisic acid.

植物的稳态调节看起来不如哺乳动物明显，但植物同样在不断监测和调整内部环境。本文解释植物如何调节水势、离子浓度、气体交换、pH 和温度，重点讨论气孔行为以及脱落酸的作用。

1. What Is Homeostasis in Plants? | 什么是植物的稳态调节？

Homeostasis in plants is the maintenance of a relatively constant internal environment despite changes in the external environment. In mammals homeostasis relies heavily on the nervous and endocrine systems; plants lack these, but they use chemical signals, ion transport, water potential changes and altered gene expression to achieve similar control. The main regulated variables include cell water potential, turgor pressure, cytosolic ion concentrations such as K⁺ and Ca²⁺, pH, CO₂ and O₂ levels in photosynthetic tissues, leaf temperature and hormone concentrations.

植物的稳态调节是指在外部环境变化时，仍能维持相对稳定的内部环境。哺乳动物的稳态主要依赖神经系统和内分泌系统；植物没有这些系统，但通过化学信号、离子运输、水势变化和基因表达调整来实现类似的控制。受调节的主要变量包括细胞水势、膨压、细胞质中的 K⁺ 和 Ca²⁺ 等离子浓度、pH、光合组织中的 CO₂ 和 O₂ 浓度、叶片温度以及激素浓度。

Negative feedback is the dominant principle. For example, a fall in soil water availability is sensed by root cells, which produce abscisic acid. The hormone travels to leaves and causes stomatal closure. This reduces water loss by transpiration, so leaf water potential rises back towards its set point.

负反馈是主要调节原理。例如，土壤水分减少被根细胞感知，根细胞产生脱落酸。激素运输到叶片，引起气孔关闭。这减少了蒸腾失水，使叶水势回升到设定范围。

2. Water Potential and Turgor as the Core Set Point | 水势与膨压作为核心设定点

Water potential (Ψ) is the property that determines the direction of water movement; water moves from regions of higher Ψ to lower Ψ. It is usually measured in megapascals (MPa), and pure water at standard conditions has Ψ =

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