RT Journal Article SR Electronic T1 Water Movement through the Surfaces of the Grape Berry and Its Stem JF American Journal of Enology and Viticulture JO Am. J. Enol. Vitic. FD American Society for Enology and Viticulture SP ajev.2011.10056 DO 10.5344/ajev.2011.10056 A1 Tobias Becker A1 Moritz Knoche YR 2011 UL http://www.ajevonline.org/content/early/2011/03/08/ajev.2011.10056.abstract AB Water uptake and transpiration of detached grape berries (Vitis vinifera L. cv. Chardonnay, Müller-Thurgau, Riesling) were determined gravimetrically. Water movement was linearly related to time. Abrading the cuticle from the berry surface increased rates of uptake and transpiration 73- and 7-fold, respectively. Restricting water movement to the berry surface by sealing the stem including the stem/fruit juncture decreased rates of uptake (−76%) and transpiration (−16%). Rates of uptake were weakly those of transpiration were closely related to the surface area of the berry. Transpiration rates were higher in the stylar (+44%) than the cheek region. The water potential of developing Riesling berries (Ψfruit) was approximately constant between 20 and 76 days after full bloom (DAFB) ranging from −0.52 (± 0.18) to −0.58 (± 0.15) MPa and decreased thereafter to −1.56 (± 0.04) MPa at 131 DAFB when the solute potential was −3.66 (± 0.01) MPa. The permeability of the cuticle of Riesling berries to water uptake decreased from 43.3 (± 7.0) nm/s to 4.1 (± 1.2) nm/s between 28 and 131 DAFB, respectively, that for transpiration from 7.3 (± 0.3) nm/s to 1.6 (± 0.0) nm/s. Water uptake was not affected by NaCl, KCl, CaCl2, FeCl3 or AlCl3 (all at 1 to 100 mM). Only MgCl2 slightly increased water uptake. Increasing temperature from 2 to 35°C increased rates of water uptake in Riesling and Müller-Thurgau berries 2.2-fold [equiv. energy of activation 19.6 (± 3.3) kJ/mol]. Flow rates, fluxes and permeabilities of stem and berry surfaces in water uptake and transpiration are discussed and a water balance for vascular and surface transport of water in a Riesling berry under hypothetical weather conditions is estimated.