Transpiration and crop yields

Theoretical and practical aspects of the transpiration of crops in the field are discussed and he concludes that the relationship between transpiration and total dry matter production is much less affected by growing conditions than has been supposed. In semi-arid and arid regions, this relationship depends on plant species and on free water evaporation, while in cloudy regions it depends mainly on plant species. This difference is due to light intensity; in cloudy regions assimilation is less than in regions with more bright sunshine. The relationship between transpiration and dry matter in plants grown in the field with limited available water is often similar to that for container-grown plants. Where water is not limited, however, transpiration tends to increase, although even when transpiration becomes considerably greater than free water evaporation, the relationship between transpiration and production in the field resembles that of plants growing in containers. The relationship between transpiration and total dry matter production is not affected by the ability of plants to withstand periods of drought, but the amount of marketable product and total amount of water which is transpired during the growing period may depend largely on their drought resistance.