Résumé
A simple model based on Ohm’s law analogy and relating the water potential gradient between stem and leaf and the transpiration of the leaf (T) was tested on peach trees (1) at the leaf scale where T was calculated from an application of Fick’s law on diffusion and (2) at the whole plant scale, where T was measured gravimetrically. Results show that the water potential gradient and the leaf transpiration are linearly related with a coefficient of determination (r2) equal to 0.59 at the leaf scale and to 0.91 at the whole plant scale, for transpiration values lower than 40 mg · s−1.