PT  - JOURNAL ARTICLE
AU  - R. Paul Schreiner
AU  - James Osborne
AU  - Patricia A. Skinkis
TI  - Nitrogen Requirements of Pinot noir Based on Growth Parameters, Must Composition, and Fermentation Behavior
AID  - 10.5344/ajev.2017.17043
DP  - 2017 Oct 30
TA  - American Journal of Enology and Viticulture
PG  - ajev.2017.17043
4099  - http://www.ajevonline.org/content/early/2017/10/25/ajev.2017.17043.short
4100  - http://www.ajevonline.org/content/early/2017/10/25/ajev.2017.17043.full
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 the two lowest N rates in subsequent years. Fruitfulness and fruit set were slightly reduced by low N, while flower number of inflorescences was unaffected by N. 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 about 200 mg N/L in the Control to as low as 25 mg N/L in 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 when vines are cropped at typical levels for premium wine production in the region. YAN levels as low as 100 mg N/L might be a better production target for wineries to achieve minimum fermentation requirements of Pinot noir.