2021-22 OWB Funded Research | Rootstock effects on mature Pinot noir growth and productivity under cool climate, dry-farmed conditions

In its 2021-22 fiscal year, the Oregon Wine Board of Directors granted $289,000 to researchers for six projects with the potential to advance quality grape growing and winemaking in Oregon. The update below is part of a series to let industry members know about the status of these projects. 

Dr. Patty Skinkis is a professor and viticulture extension specialist in the Department of Horticulture at Oregon State University and member of the Oregon Wine Research Institute. She has prepared the update for the project below.

Rootstock effects on mature Pinot noir growth and productivity under cool climate, dry-farmed conditions

Project objectives:

1. Compare vine growth stages, vine health, and fruit productivity of Pinot noir grafted to different rootstocks.
2. Compare differences in fruit composition of Pinot noir grafted to different rootstocks.
3. Quantify vine water stress response of key rootstocks.

Importance to the Oregon wine community:

The wine industry has continued interest in rootstock performance with new vineyard development and seasonal climate change. However, Oregon growers have little experience with rootstocks outside of what is currently being grown, and there is no data available from regional field studies to indicate the best-performing rootstocks for vineyards long-term under the Willamette Valley’s cool climate and mostly dry-farmed vineyards. With recent changes in vineyard production, such as increased target yields (i.e., less crop thinning) and the movement toward no-till practices and/or no herbicide use, the traditional vigor-reducing rootstocks may not perform well. This may manifest as poor growth, new pest issues, and yield reduction. This study is evaluating a mature rootstock trial to help provide industry with information on best-suited rootstocks.

Progress so far:

Vine growth, yield, and fruit composition of Pinot noir grafted to 19 rootstocks and own-rooted vines were quantified since 2019. The vineyard was 23 years old at the outset of the evaluation period, 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, Riparia Gloire and 44-53 had the lowest pruning weights, indicating low vigor, and 1616, 5BB, 125AA, and 161-49 had the highest pruning weights, indicating vigorous vines. The commonly grown 101-14 and 3309C had lower pruning weights than most other rootstocks, although they fell within the optimum vigor range for the study. Most rootstocks did not differ in yield, except with 420A having higher yields than Schwarzmann, 44-53, Riparia Gloire, and own-rooted vines, based on 3-year means. Berry ripeness differed by rootstock, with higher vigor vines having lower sugars, lower pH and higher titratable acidity by harvest, but all within acceptable ranges for wine production (>23˚Brix at harvest). We anticipated that rootstock may impact berry phenolics through vine stress and/or differences in canopy microclimate. Riparia Gloire had higher concentrations of anthocyanin, phenolics, and tannins in the berries compared to other rootstocks, but berries from most rootstocks did not differ from each other. We also anticipated that vine vigor conferred by rootstock may affect berry nitrogen, and lower vigor vines had lower nitrogen compared to those of high vine vigor. So far, the findings indicate rootstock has the greatest impact on vegetative growth and yield, thereby causing differences in vine balance that has the greatest impact on from vines most out of balance (both high and low vigor).

Next steps:

This research continues in 2022 to evaluate the seasonal effects on the vine performance. The 2022 season will be the second season of water stress measures to discern rootstock drought tolerance but the fourth season looking at impacts on growth, yield, and basic fruit ripeness. As we advance this research, we will focus on different aspects of vine performance over time. We will also update the Rootstocks for Oregon Extension publication to provide practical information for industry.

 

Primary support for this project is provided by the Oregon Wine Board grant. Additional support was provided by Erath Family Foundation for purchase of equipment to allow more streamlined plant water stress data collection that started in 2021.