If a plant does not have enough water to open its guard cells...?

Question

how would this affect its rate of transpiration?

Answer 1

This would slow down the rate of transpiration because if the guard cells are shut from lack of water, then less water exits through the stomata, slowing the rate of transpiration.

Answer 2

In plants, a specialized cell on the under surface of leaves for controlling gas exchange( water vapor, oxygen and carbon dioxide through the stoma) are called Guard cells which occur in pairs and are shaped so that a pore, or stomata, exists between them. They can change shape with the result that the pore disappears. During warm weather, when a plant is in danger of losing excessive water, the guard cells close, cutting down evaporation from the interior of the leaf by reducing its transpiration rate.

The stomata close when too much water is lost, or when not enough supply exists.The osmotic pressure of the stomata is far larger in the guard cells than in the subsidiary cells. This ratio shifts in favor of the subsidiary cells when the stomata are closed, and we knew that Guard cells can emit water into three different directions:

1-outwards,

2-into the neighboring subsidiary cell, and

3-into the respiratory cavity that is a part of the inter-cellular system lying beneath the guard cells.