RT Journal Article SR Electronic T1 N, P, and K Supply to Pinot noir Grapevines: Impact on Vine Nutrient Status, Growth, Physiology, and Yield JF American Journal of Enology and Viticulture JO Am. J. Enol. Vitic. FD American Society for Enology and Viticulture SP 26 OP 38 DO 10.5344/ajev.2012.12064 VO 64 IS 1 A1 Schreiner, R. Paul A1 Lee, Jungmin A1 Skinkis, Patricia A. YR 2013 UL http://www.ajevonline.org/content/64/1/26.abstract AB Pinot noir grapevines (self-rooted Pommard clone) were grown in a pot-in-pot sand culture vineyard to examine the impact of low N, P, and K supply on vine growth and physiology. Four-year-old vines were given either full nutrition (Control) or reduced levels of each N, P, and K supplied at 50%, 20%, or 10% of the Control rate with all other nutrients held constant over three years (2006–2008). Vine growth, nutrient status, photosynthetic parameters, yield, and berry quality were monitored. The N, P, and K status of vines was reduced by each of the intended treatments, although N and P concentrations in leaf blades and petioles were reduced earlier and to a greater extent than K. Low N treatments reduced dormant season cane weights in all years, shoot lengths and leaf area in 2008, and fruit yield in 2008. Yield reduction under low N supply in 2008 was primarily a result of reduced berry size. Low N also reduced single leaf photosynthesis and quantum efficiency of photosystem II in 2008, while low P and K did not. Juice YAN (yeast assimilable nitrogen) levels were greatly reduced by low N supply in 2007 and 2008, although YAN was lower in 2007 across all treatments. Low P and low K supply did not alter growth or yield. Low P supply reduced juice P concentrations, but low K supply did not alter juice K. Reduced yield, growth, and juice YAN levels in low N treatments provide a framework to refine leaf blade and petiole N standards for Pinot noir grown in the region, but limiting levels of P and K were not as clearly defined.