What is the advantages of a closed stomata to a plant when water is in short supply?
When water is in short supply it is advantageous for a plant to close its stomata because this stops transpiration and then the plant will not use as much water. However, this also has its disadvantages. Because there is no transpiration, water is moved up the xylem only by means of the positive pressure build up in the roots, a process that is much, much slower. Additionally, the plant can not get carbon dioxide form the air to use in photosynthesis and instead oxygen levels build up in the plant which, at high concentrations, can be harmful. Overall the disadvantages outweigh the advantages but plants have adapted other ways for dealing with water scarcity.
