The primary advantage for a plant in closing its stomata is to conserve water by preventing excessive water loss through transpiration.
Here's a more detailed explanation:
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Water Conservation: Stomata are small pores on the surface of plant leaves that allow for gas exchange (carbon dioxide in for photosynthesis and oxygen out as a byproduct). However, water also escapes through these pores in a process called transpiration. When water is scarce, closing the stomata significantly reduces transpiration, helping the plant survive drought conditions. The short answer excerpt provided confirms this: "In short supply of water, the closed stomata help in maintaining the water level in the plant thereby avoiding the evaporation and loss of water content."
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Maintaining Turgor Pressure: Water is crucial for maintaining turgor pressure within plant cells, which provides rigidity and support. By closing stomata, plants can prevent excessive water loss, helping maintain turgor and preventing wilting.
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Short-Term Survival: While photosynthesis is essential for long-term survival, conserving water becomes more critical in the short term under drought stress. Plants can temporarily survive by closing their stomata, even if it means reducing photosynthetic activity.
However, it's important to note that closing stomata also has disadvantages:
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Reduced Photosynthesis: Closed stomata prevent carbon dioxide from entering the leaf, significantly reducing or even halting photosynthesis.
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Increased Leaf Temperature: Transpiration also cools the leaves. When stomata are closed, leaves can overheat, potentially damaging tissues.
Therefore, stomatal closure is a balancing act. Plants must balance the need for water conservation with the need for carbon dioxide uptake for photosynthesis and temperature regulation.
