No evidence for droplet size effects on the penetration of 14C-proline across astomatous isolated pear (Pyrus communis L.) leaf cuticles

The effect of droplet size (10-1000 nl) on the rate constants of penetration of C-14-proline across isolated adaxial astomatous cuticles of Pyrus communis L. cv. 'Conference' was tested after droplet drying in the presence of the surfactant Tween 80 in the droplet residues at 20 degreesC and 90 % relative humidity using a method of paired samples. The cumulative interface area between the droplet residues and the cuticular membrane was kept constant by adjusting the number of droplets per cuticle. Even though scintillation counting is a very sensitive method and the paired sample method used here provides the most precise test available, no evidence for the existence of droplet size effects on the rate constants of penetration was obtained.