RT Journal Article SR Electronic T1 Nitrogen Requirements of Pinot noir Based on Growth Parameters, Must Composition, and Fermentation Behavior JF American Journal of Enology and Viticulture JO Am J Enol Vitic. FD American Society for Enology and Viticulture SP 45 OP 58 DO 10.5344/ajev.2017.17043 VO 69 IS 1 A1 R. Paul Schreiner A1 James Osborne A1 Patricia A. Skinkis YR 2018 UL http://www.ajevonline.org/content/69/1/45.abstract AB A study to reassess the nitrogen (N) requirements for Pinot noir was carried out using a pot-in-pot vineyard where N inputs were carefully controlled. Pinot noir grafted on 101-14 rootstock was exposed to five levels of N supply beginning in their fourth growing season, and vine productivity, berry chemistry, and must fermentation dynamics were studied over three years. N supply altered the N status of vines in accordance with expectations. Varying N had a greater impact on vegetative growth parameters than upon reproductive responses. For example, at veraison, leaf area of vines exposed to the three lowest rates of N was reduced in all years, but yield was only reduced at the lowest N rate in the first year and at the two lowest N rates in subsequent years. Fruitfulness and fruit set were reduced slightly by low N, while flower number of inflorescences was unaffected. Effects on berry maturity indices at harvest were generally small, but effects on must yeast assimilable nitrogen (YAN) concentrations were large. YAN was reduced from ~200 mg N/L in the Control to as low as 25 mg N/L at the lowest N rate after three years. Treatments with lower YAN required more time to complete alcoholic fermentation, particularly those with YAN below 100 mg N/L. However, all musts fermented to dryness. Reducing vegetative growth of Pinot noir can be achieved prior to reducing yield by reducing N status when vines are cropped at levels typical for premium wine production in the region. YAN levels as low as 100 mg N/L may be a better production target for wineries to achieve minimum fermentation requirements of Pinot noir.