Effects of primary or secondary bud shoot growth, and cultivar on mid-day leaf photosynthetic rate (A, B), stomatal conductance (C, D), and intrinsic water use efficiency (E, F) for field grown Vitis vinifera ‘Grenache’ and ‘Cabernet Sauvignon’ vines grafted to 110R rootstocks. Each bar represents least square mean of approximately 180 measurements (2016 and 2017 data was pooled). Letters above each bar represent differences between bud type, or cultivar for each date. If a letter is not present, means are not  significantly different. (Tukey-Kramer test, P ≤ 0.05). Error bars represent SE for each bud type or cultivar.