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 340
OP 350
DO 10.5344/ajev.2011.10056
VO 62
IS 3
A1 Becker, Tobias
A1 Knoche, Moritz
YR 2011
UL http://www.ajevonline.org/content/62/3/340.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 related and 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, and that for transpiration decreased 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.