Table 3

Ion concentration of opposite to the cluster leaf blades sampled at veraison over four years (2012 to 2015) on field-grown cv. Barbera grapevines growing in high (H), medium (M), and low (L) vigor zones and subjected to different N fertilization (urea) regimes. C: unfertilized control; S: uniform N supply at 60 kg/ha; and VRA: variable rate N application (0 kg in H, 60 kg/ha in M, and 120 kg/ha in L).