Author : Nopadol Riablershirun

Summary : Rice and cotton plants were grown outdoor in medium-size plastic containers containing silty clay loam or sandy loam soil. When two months old, these were transfered to a wind tunnel and subjected to two aerodynamic conditions. Measurement of potential, actual and relative water content showed that when soil water is unlimited, potential transpiration was mainly controlled by evaporative demand. However, when soil water stress set in, the effect of evaporative demand declined. The simple effect of soil water stress was to reduce transpiration which is opposite of that evaporative demand. Except for rice in silty clay loam, the effect of soil water stress on transpiration was much greater than that of the evaporative demand at a lower range of water stress, especially in sandy loam soil.