Rootstock Effects on Mature Pinot Noir Growth and Productivity under Cool Climate, Dry Farmed Conditions

(Year 1) Vine growth, yield, and fruit composition of Pinot noir grafted to 19 rootstocks and own-rooted vines were quantified during 2020. The vineyard was 23-years-old, and we hypothesized cumulative impacts of the rootstock on vine growth would be distinguished by rootstock. Specifically, we hypothesized that Riparia Gloire and other vigor-reducing rootstocks such as 101-14, 3309C, and 420A would have reduced canopy growth compared to other rootstocks not commonly planted in Oregon due to high vigor potential, such as 110R, 140R, 1103P, and 161- 49. Results show that the majority of rootstocks performed similarly for vine canopy growth and fruit production. However, there were some key differences noted in this first year of evaluation. Dormant pruning weights in early 2020 indicate that Riparia Gloire, 44-53, and 3309C had the lowest pruning weights, indicating low vigor vines, and 161-49 and 1616 had the highest pruning weights, indicating highly vigorous vines. Despite vigor differences noted during pruning, there were few to no differences in growth stage advancement at bud break, bloom, or fruit set. By the start of véraison Riparia Gloire and SO4 had the most advanced color development while 101- 14, 3309C, and own-rooted were the least advanced. However, within a 6 d window, the rootstocks became less different in percent of berries colored, and 3309C had the highest rate of color change. There were no differences in rootstock yield except for Riparia Gloire and SO4, which had the lowest and highest yields, respectively. Berry ripeness did not differ for most rootstocks. However, Schawarzmann had higher Brix than 420A, 5BB, 125AA, own-rooted, 5CTE and 99R. There were few differences in pH and variable differences in titratable acidity. We anticipated that variations in canopy size created by rootstock vigor may impact berry phenolics through vine stress and/or differences in canopy microclimate. However, there were no rootstock differences in total anthocyanin or phenolic content. There were minor differences in total tannins. We also anticipated that vine vigor conferred by rootstock may affect berry nitrogen, but there were few differences in juice primary amino N except for 1616 and 5BB that had more than double the primary amino N than 44-53 and own-rooted vines. This first year of data analysis suggests that rootstock has the greatest impact on vegetative growth and yield, thereby causing some differences in vine balance. There is less impact on Pinot noir phenological advancement, fruit ripeness, berry N or phenolics at harvest.