Can Plants Lose Water When Stomata Closed?

Plants are fascinating organisms that are capable of performing photosynthesis and creating their own food. However, even though they don't need to hunt for their meal, plants require water to survive. Water is essential for plant growth, and it helps to transport nutrients and minerals through the plant's vascular system. But what happens to a plant's water needs when the stomata are closed? Can plants lose water when stomata closed?

What are Stomata?

Before exploring the question of whether plants can lose water when stomata are closed, it's essential to understand what stomata are. Stomata are small pores or openings found on the leaves, stem, and other parts of a plant. They allow for the exchange of gases such as carbon dioxide and oxygen, and also control water loss through the process of transpiration.

Stomata Closure Mechanism

The closure of stomata is a natural process that helps the plant conserve water. Stomata closure is triggered by factors such as high temperatures, low humidity, or low soil water content. When the plant perceives any of these factors, it releases a hormone called Abscisic Acid (ABA). ABA signal causes the plants' guard cells to close, effectively sealing the stomata, and decreasing water loss through transpiration.

Can Plants Lose Water When Stomata Closed?

The general assumption is that when the stomata are closed, plants should not lose water. However, studies have shown that closed stomata do not completely prevent water loss. A small amount of water vapor can still exit the plant's tissues through the cuticle, which is the layer of wax covering the plant's leaves.

This means that plants that close their stomata to minimize water loss rely on the cuticle's water-repellent properties to prevent excessive water loss. The size and shape of stomata and the thickness of the cuticle vary from plant to plant, and this determines the degree to which a plant can control water loss through transpiration when the stomata are closed.

Consequences of Increased Water Loss

Plants that lose water excessively run the risk of wilting, which can lead to reduced growth and even death in extreme cases. Wilting happens when the plant can't draw sufficient moisture from the soil and loses more water than it can take up. The consequences of increased water loss through cuticle tissue when the stomata are closed are reduced growth, decreased yields, and overall plant productivity.

The Bottom Line

While plants can minimize water loss by closing their stomata, they can still lose a small amount of water through their cuticles. The degree to which a plant controls water loss when the stomata is closed depends on the species and their specialization to their specific environment. It's important to understand that plants must balance their need for water with their need to conserve water when necessary. A deeper understanding of plant water loss mechanisms can help us protect and conserve our natural resources.