EXPERIMENTAL ANALYSIS OF FLUORIDE SUSCEPTIBILITY OF GRAPEVINE (VITIS VINIFERA L.): LEAF DEVELOPMENT DURING FOUR SUCCESSIVE SEASONS OF FUMIGATION

Abstract

SUMMARYLeaf development was studied in potted specimens of grape vine (Vitis vinifera L., varieties Chardonnay, Gordo and Traminer) that were exposed to hydrogen fluoride in controlled environment cabinets during four successive growing seasons. The duration of exposures varied from 54 d in the second season to 159 d in the fourth. There was no significant or consistent effect of fluoride on the numbers of leaves produced on major or lateral shoots in any variety. Leaf size during the first growth flush of a season was not influenced by the present or previous exposure of plants to ambient fluoride concentrations up to 1.5μm F m−3. Mature leaf size during the middle or latter portion of the fourth season of fumigation was significantly reduced in the Chardonnay and Traminer varieties as a result of exposure to fluoride concentrations of 0.64μg m−3 or more. Leaf size in the variety Gordo was not affected by ambient fluoride concentrations up to 1.5μg F m−3. Stomatal frequency and size in the variety Chardonnay, and leaf water vapour conductance in all varieties were not affected by ambient fluoride concentrations up to 1.05μg F m−3. The work demonstrates variations in response of grape vine leaves to ambient conditions at different stages of the growing season.