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56 WINES&VINES December 2017 GRAPEGROWING PRACTICAL WINERY & VINEYARD periods (bud break to bloom, bloom to vérai- son, and véraison to harvest) were calculated by subtracting the mean value at an earlier growth stage from each replicate at a later growth stage. Biomass and nutrient uptake Biomass: Total vine biomass increased the most from bloom to véraison, increased from véraison to harvest and declined from harvest to leaf fall, remaining at that level until dor- mancy (see table "Relative Increase of Vine Biomass and Relative Nutrient Uptake"). While it appears from changes in biomass of sampled tissues (see "Changes in Biomass of Sampled Tissues" on page 54) that total vine biomass increased from bud break to bloom, this was not significant. However, the loss of biomass of the permanent vine structures (roots + trunk) between bud break and bloom was significant. The pattern of biomass changes found here, with peak increase be- tween bloom and véraison, is similar to most previous whole-vine studies where roots have been accounted for. 2,3,5,6,7,8,9 Nitrogen: Nitrogen uptake followed a unique pattern compared to other nutrients. Vine nitrogen uptake was greatest between bud break and bloom, followed by less up- take between véraison and harvest, with essentially no uptake after véraison (see "Changes in Nitrogen Content" on page 55). Between bud break and véraison, nitrogen was taken up from the soil and remobilized from storage in the roots and trunks to sup- port canopy nitrogen needs. The bulk of the nitrogen remobilized to the canopy came from the smallest roots. Remobilized nitrogen supplied 41% of canopy nitrogen requirements in 2007 and 30% in 2008 between bud break and véraison. The amount of nitrogen remobilized was less than previous findings in 23-year-old Pinot Noir vines, where approximately 50% of canopy nitrogen came from stored reserves. 11 However, nitrogen remobilized in four- year-old Pinot Noir was greater than previ- ous results in young grapevines. For example, no nitrogen remobilization occurred in three- year-old Concords, nor in two-year-old Thompson Seedless vines, 1,2 and only 15%- 20% of nitrogen was remobilized in two- year-old Chenin Blanc grapevines. 3,5 The majority of the nitrogen that was taken up from the soil or remobilized ended up in the leaf blades, which reached maxi- mum nitrogen content at véraison. Leaf ni- trogen content declined between véraison and harvest, partly supplying fruit needs. The overall pattern for nitrogen uptake was similar to a previous study on 23-year-old Pinot Noir vines in the Willamette Valley 11 but differs from other whole-vine nitrogen uptake studies. 2,3,5,6,7,8,9 Phosphorus: Uptake of phosphorus was similar from bud break to bloom and from bloom to véraison, with each time period accounting for about 40% of phosphorus uptake by fruit maturity (see table "Relative Increase of Vine Biomass and Relative Nutri- ent Uptake"). The remaining 20% of phos- phorus uptake occurred between véraison and harvest. Even though biomass in the roots and trunks decreased between bud break and bloom, the associated decrease in phosphorus content in permanent vine parts during this time was not significant. There- Nitrogen uptake followed a unique pattern compared to other nutrients, with the greatest uptake occurring between bud break and bloom. WINES & VINES DIRECTORY/BUYER'S GUIDE PRE-ORDER Pre-order the 2018 Wines & Vines Directory/Buyer's Guide for only $95.* Get the most current and comprehensive print and online guide to wine and grape industry professionals, products and services in North America. PRE-ORDER TODAY! winesandvines.com/order FREE SHIPPING* *Print edition available mid-January 2018. *$95 rate includes shipping within the U.S. only. Rates for other countries apply.