Leaf blade and petiole nitrogen (N) concentrations at bloom and veraison in Pinot noir grapevines grown in microplots at varying rates of N from 2012 to 2014. Leaf blade and petiole nitrogen (N) concentrations at bloom and veraison in Pinot noir grapevines grown in microplots at varying rates of N from 2012 to 2014. Data are means and standard errors of the mean for each factor (n = 20 for year, n = 12 for N supply, n = 4 for Y · N supply interaction). R. Paul Schreiner et al. Am J Enol Vitic. 2018;69:45-58 ©2018 by the American Society for Enology and Viticulture