Simulating of leaf wetness duration within a potato canopy

A leaf wetness duration experiment was carried out in a potato field in the centre of the Netherlands during the growing season of 2003. A within-canopy dew simulation model was applied to simulate leaf wetness distribution in the canopy caused by dew and rainfall. The dew model is an extension of an earlier-developed energy budget model, distinguishing three layers within the potato canopy. To run the dew model successfully, information on the above-canopy wind speed, air temperature, humidity and net radiation as well as the within-canopy temperature and humidity must be available. In most cases leaf wetting starts in the top layer followed by the centre and the bottom layer, in that order. Leaf drying shortly after sunrise takes place in the same order. Leaf wetness lasted longest in the bottom layer. Rainfall was accounted for by applying an interception model. The results of the dew model agreed well with leaf wetness recorded with a resistance grid.