| Abstract: | A new method is described for measuring the stomatal resistanceto diffusion in leaves. It consists of measuring the radioactivityof air samples which have diffused through a leaf from a porometercontainer enriched with radioactive argon(41A). Details of thecalibration are given together with the methods adopted to determinethe accuracy of measurement and the optimum time of sampling.Results suggest that in the material investigated the measurementsobtained are essentially those of stomatal resistance.In onesmall experiment inter and intra plant variability in stomatalresistance was investigated; in another, the diffusion porometerwas used to compare the daily march of stomatal resistance withthe rate of transpiration in plants growing under four differentsoil-moisture regimes. |
