PLAUT, Z., Institute of Soils and Water, Agricltural Research Organization, Volcani Center, Bet Dagan, Israel, Department of Floriculture, Hebrew University of Jerusalem, Faculty of Agriculture, Rehovot, Israel
ZIESLIN, N., Institute of Soils and Water, Agricltural Research Organization, Volcani Center, Bet Dagan, Israel, Department of Floriculture, Hebrew University of Jerusalem, Faculty of Agriculture, Rehovot, Israel

The effect of canopy wetting of rose (Rosa hybrida) plants on transpiration rate, stomatal resistance, plant water potential, ion concentration in leaves, and several growth parameters was investigated. Plants were grown in a greenhouse and their canopies were exposed to wetting cycles during the daytime. Canopy wetting decreased transpiration rate and increased diffusive resistance to water vapor transfer. Plant water potential was only slightly increased by wetting, mainly in the spring. Canopy wetting did not prevent the decrease in CO2 fixation, which took place before midday when plant water potential dropped below – 10 bars during a rise in radiation intensity. The concentrations of Cl− and Ca2+ decreased in wetted leaves, while the concentration of Na+ was increased and other cations were hardly affected. Canopy wetting inhibited growth rate of rose shoots and flower formation, and increased the average flower weight. Copyright © 1977, Wiley Blackwell. All rights reserved