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54 WINES&VINES December 2017 GRAPEGROWING PRACTICAL WINERY & VINEYARD S easonal uptake from the soil and use of nitrogen in grapevines has been examined in studies from numerous grapegrowing regions. 1-3, 5-11 Uptake of other macronutrients including phospho- rus, potassium, calcium and magnesium has received less attention, 4,9,11 and no published study has determined the timing or quantities of micronutrient uptake of manganese, boron, zinc or copper for field-grown grapevines. The majority of total seasonal nutrient uptake from vineyard soils (mainly for nitro- gen) has been reported to occur between bloom and véraison in most studies on wine grapes (Vitis vinifera) and Concord grapes (Vitis labrusca) coincident with the increase in total vine biomass. 2,3,5,6,7,9 However, some studies of wine grapes have found greater nitrogen uptake from vineyard soils between bud break and bloom than between bloom and véraison, 1,8,11 even though the bulk of total vine biomass increase still occurred between bloom and véraison. The majority of phosphorus uptake oc- curred early in the growing season (close to the time of flowering) in Pinot Noir, 11 while the uptake for potassium, calcium and mag- nesium has mostly been reported between bloom and véraison. 4,9,11 Given the differences observed in nutrient uptake of whole vines from previous trials, the nutrient uptake of young Pinot Noir vines was studied to provide growers with better information about the nutrient needs of young vines and when nutrient uptake occurs to provide better guidelines to manage nutri- ent inputs for young vineyards. Key finding: Nutrient uptake and remobilization varies by specific nutrient For nitrogen (N), maximal uptake from the vineyard soil occurred early in the season with most uptake occurring before bloom. Uptake of phosphorus (P) and sulfur (S) were early, with similar quantities of these elements taken up between bud break and bloom and between bloom and véraison. All other macronutrients—potassium (K), cal- cium (Ca) and magnesium (Mg)—and mi- c r o n u t r i e n t s — b o r o n ( B ) , z i n c ( Z n ) , manganese (Mn) and copper (Cu)—had peak uptake between bloom and véraison. Small quantities of all nutrients except N and B were taken up from the soil during the ripen- ing period (véraison to harvest). In addition, N, P, K and S were remobilized from leaves during the ripening period to support fruit needs as well as recharging these elements in the roots. Remobilization of nutrients from perma- nent vine structures helped supply early sea- son canopy needs for N, K and S. More N was remobilized from reserves than any other nutrient, and this lasted until véraison, sup- plying about 35% of the canopy N between bud break and véraison. Remobilization of K and S occurred only until bloom and contrib- uted about 30% of the canopy increase in these elements up to that time. Phosphorus was not remobilized from storage to support the developing canopy, contrary to previous results with older Pinot Noir grapevines. 11 The reason for this is most likely due to the smaller root system of these young vines, combined Probing Nutrient Needs of Pinot Noir Vines Knowing when nutrient uptake occurs in young vines can aid input management By R. Paul Schreiner n Clusters n Leaves n Petioles n Shoots n Fruiting Canes n Scion Trunk n Rootstock Trunk n Woody Roots (>4 mm) n Small Roots (1-4 mm) Four-year-old grapevines in a micro-plot are evaluated over two growing seasons. Data are means for each plant part, with standard errors of the mean shown for total vine biomass (n=10). Letters designate major phenological stages when vines were destructively harvested. BB=bud break; BL=bloom; VR=véraison; HA=harvest; LF=leaf fall; PR=pruning at winter dormancy. CHANGES IN BIOMASS OF SAMPLED TISSUES 2,000 1,800 1,600 1,400 1,200 1,000 800 600 400 200 0 April '07 June '07 Aug. '07 Oct. '07 Dec. '07 Feb. '08 April '08 June '08 Aug. '08 Oct. '08 Dec. '08 Feb. '09 Dry Mass (g) BB BL VR HA LF PR BB BL VR HA LF PR