RT Journal Article
SR Electronic
T1 Validation of a Model for the Growth and Development of the Thompson Seedless Grapevine. II. Phenology
JF American Journal of Enology and Viticulture
JO Am J Enol Vitic.
FD American Society for Enology and Viticulture
SP 283
OP 289
DO 10.5344/ajev.1985.36.4.283
VO 36
IS 4
A1 D. W. Williams
A1 H. L. Andris
A1 R. H. Beede
A1 D. A. Luvisi
A1 M. V. K. Norton
A1 L. E. Williams
YR 1985
UL http://www.ajevonline.org/content/36/4/283.abstract
AB This study compares the prediction of phenology models for the grapevine cultivar Thompson Seedless that are based on degree days (°D above 10°C) with patterns observed in the field. Budbreak, bloom, and the development of total soluble solids were monitored in six vineyards over a latitudinal range of 300 km in the San Joaquin Valley of California in 1983. The models predicted dates of 50% budbreak and 50% bloom within a few days of the observed events. Relative calendar timing followed the expected latitudinal trends, with earliest budbreak and bloom dates observed at the southernmost sites. The model predicted maturity (20° to 21.5°Brix) reasonably at four vineyards and underestimated it at the other two, one of which had vines that were water stressed and lightly cropped relative to the others. Predictions of °Brix differed substantially from observations in the range 14° to 18° at most sites. The factors influencing vine phenology, including temperature, solar radiation, water availability, and vine management practices, are discussed.