Adequate supplies of water, carbon dioxide as well as the availability of nutrients from the soil affect photosynthesis. During plant respiration, carbohydrates combine with oxygen and is reduced to carbon dioxide and water, and heat. While photosynthesis operates only during day when sunshine is available, respiration goes on both night and day. Plant growth occurs so long as photosynthesis exceeds respiration. Transpiration Transpiration is the loss of water from plant leaves.
Water exits the leaf through stomata, which are tiny pore spaces in the leaf.
The rate of transpiration depends on air temperature and solar radiation. As pointed out earlier, transpiration is a cooing process for plants when temperatures or incident light rise too high and cause heating of the plant. Low humidity, often aided by windy conditions, creates a vapor gradient between the plant and the air. This too induces transpiration. Soil factors are important control over transpiration.