EFFECTS OF HUMIDITY ON STOMATAL DENSITY AND ITS RELATION TO LEAF CONDUCTANCE

The effects of air humidity in the range 0.2-1.6 kPa vapour pressure deficit on stomatal density was investigated with glasshouse cucumber (Cucumis sativus L.), tomato (Lycopersicon esculentum Mill.), sweet pepper (Capsicum annuum L.) and eggplant (Solanum melongena L.). Stomatal density of tomato, eggplant and sweet pepper was higher at high humidity. The length of the pore increased at high humidity with cucumber, tomato and sweet pepper; the width was affected only with sweet pepper. No significant differences in leaf conductances were observed between plants grown under different humidity pretreatments. It is concluded that stomatal density and size as affected by humidity in the range investigated do not significantly influence leaf conductance.