Determination de la transpiration au moyen de l'eau tritiee

Summary Tritiated water is used to measure the transpiration rate of trees in forest. A simple rapid method for extracting water from plant tissues was developed. To test the accuracy of the tritium method, the authors carried out a comparative study between this method and the weight-loss method. High correlations (r=0.99) between the two methods were obtained. But there was an increase of about 15% by the tritium method, assuming that transpiration values obtained by weight-loss were accurate.The data showed that the activity of tritium in twigs give a better transpiration rate than the activity determined only in needles.It is concluded that the tritiated water method is valid for measurement of tree transpiration.