Although only a small portion of water absorbed by the plant is used in photosynthesis, a shortage of water does affect the rate photosynthesis occurs. Even a slight deficiency of water results in significant reduction in the crop yield. The lack of water not only limits the amount of water, but also the quantity of carbon dioxide available for photosynthesis. This is because in response to drying the leaves close their stomata in order to conserve water being lost as water vapor through them. Care should be take to assure that both optimal oxygen and water are available to the roots at all times.
