Some considerations on the diurnal variation of transpiration.

Abstract

The diurnal variation of the measured transpiration from pots with alfalfa plants and the readings of several evaporimeters for a case reported by Briggs and Shantz are compared with the calculated values according to Penman's theory. The influence of radiation on transpiration and evaporation is clearly illustrated. The ratio between transpiration and calculated evaporation is almost constant and shows less variation than the transpiration/evaporimeter-reading ratios. The differences in magnitude between the transpiration and the evaporation values and the limitations of the theoretical treatment are discussed. It is pointed out that the evaporation from isolated plants or groups of plants which project above their surroundings will usually be greater than the evaporation from a closed homogeneous vegetation with the same height as these plants. (Abstract retrieved from CAB Abstracts by CABI’s permission)