Effects of Soil NPK Supply on Pinot noir Wine Phenolics and Aroma Composition

This work evaluated the impact of vine nitrogen (N), phosphorous (P), and potassium (K) supply on Pinot noir wine composition. Pinot noir grapevines were grown in a pot-in-pot system for three years and fertigated with varying levels of N, P, or K supply while holding all other nutrients constant. N was varied from 7.50 mM total N supply (Control) to as low as 1.125 mM total N in five discreet levels, while P and K supply were each varied in four levels, with the lowest rate (0 mM) during fertigation events. Wines produced in each of the three years were analyzed. N supply had a major impact on wine composition, including effects on volatile compounds, especially fermentation-derived esters and higher alcohols. Lower rates of N supply increased the total phenolic content in wine; in general, reduced N supply led to a decrease in straight-chain esters and alcohols, but to an increase in branched-chain esters and alcohols in wine. Low-N wines also had lower levels of volatile sulfur compounds in two of the three years. N supply also affected some grape-derived compounds in wine. Reducing N supply resulted in lower concentrations of β-damascenone across all years, but the effect of N supply on monoterpenes was not consistent from year to year. Altering P supply did not have reproducible effects on wine volatiles. Changes in volatile composition in response to nutrient supply could ultimately affect aroma perception and overall wine quality, which will require further exploration.