ARS | Publication request: Influence of Water Deficit on Berry Weight Uniformity and Mass of Berry Tissue Components in Merlot

Submitted to: American Society of Enology and Viticulture Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: April 9, 2010
Publication Date: June 20, 2010
Citation: Shellie, K. 2010. Influence of water deficit on berry weight Uniformity and mass of berry tissue components in Merlot. American Society of Enology and Viticulture Annual Meeting Abstracts. p. 55-56.

Technical Abstract: Vine water deficit during development of red-skinned wine grape beneficially reduces average berry weight at harvest, but little is known about its effect on the relative growth of berries within a cluster or among tissues within a berry. The intent of this research was to test the hypothesis that water deficit during berry development differentially influenced growth of berries within a cluster and of component tissues within a berry. Fruit was harvested at maturity from field-grown grapevines cv. Merlot that were differentially irrigated in a randomized block design to maintain a high or low level of vine water stress between fruit set and harvest. Berries were detached from clusters and individually weighed to determine their weight uniformity and to obtain samples of identical weight berries from well-watered and deficit-irrigated vines. Berry weight within each irrigation regime was distributed normally and weight uniformity at maturity was unaffected by vine water status. Berries from vines with the lowest midday leaf water potential had at least 8% heavier seed fresh weight: a greater number of seeds per berry and a greater ratio of seed to berry weight. These differences in berry tissue components between irrigation regimes were independent of berry weight. Water deficit had a uniform influence on berry growth within a cluster but differentially restricted mesocarp relative to seed tissue growth. Results have implications for wine making because a greater ratio of seed to berry weight may alter the quantity of seed relative to skin-derived compounds present during fermentation.