- The purpose of this study was to determine the relative tolerance of grafted
Vitis rootstocks to low soil pH. In this capacity, the data may be pooled with results
from previous investigations to increase the overall aptitude profile of Vitis
rootstocks. A potential application of this information is that the more acid-tolerant
rootstocks could be identified and recommended for propagation and grafting, and
ultimately for vineyard planting in viticultural areas wherein acid soils are
The experiment was a completely randomized factorial layout of 22
rootstocks x 3 levels of soil pH x 5 single vine replicates. The investigation was
conducted during the establishment phase of the vines, wherein vine performance
was monitored during the first two seasons of growth. Pinot noir grapevines (FPMS clone 2A) were grafted onto 21 rootstocks (plus Pinot noir as a non-grafted control
group), which include the most common rootstocks commercially available in
North America at the time they were procured. The following rootstocks were
included: Bomer, Couderc 1616, Couderc 3309,'FOEX 333 EM, Freedom, Kober
125AA, Kober 5BB, Malegue 44-53, Millardet et de Grasset 101-14, Millardet et
de Grasset 41B, Millardet et de Grasset 420A, Paulsen 1103, Richter 110, Richter
99, Riparia Gloire, Ruggeri 140, Rupestris St. George, Salt Creek, Selection
Oppenheim 4, Schwarzmann, and Teleki 5C. Initial levels of soil treatment
included pH (H₂O) 4, 5, and 6, and were confirmed in the following year.
A pot-in-field plot was established wherein one-year old bare-rooted vines
were planted just prior to bud break. At the end of the growing season, parameters
were measured to determine plant growth, including scion shoot length, scion
intemode diameter, number of leaves per scion shoot, scion leaf chlorophyll
content, and a phenotypic response rating system based on relative expression of
vine health. Additionally, dry weights were recorded, and reserve carbohydrates
were analyzed at the end ofthe growing season to determine the post harvest
condition of each vine.
Interactions between main effects were observed for scion shoot length,
number of leaves per shoot, shoot intemode diameter, phenotypic response rating,
relative growth rate and for leaf, trunk, root and total plant dry weights.
Rootstock had a significant effect on the shoot to root ratio. Soil pH also
significantly affected the shoot to root ratio.
Trends for this study show that at soil pH 4, vines grafted to 5BB, 3309C,
110R, Freedom, and 4453M had the highest vegetative vigor on average.
Conversely, vines grafted to Bomer, Schwarzmann, 101-14, 1616C, and ownrooted
vines had the lowest vegetative vigor on average at pH 4. At pH 5, the trend
was for vines grafted to Schwarzmann, F333EM, 125AA, 101-14, and 140Ru to
exhibit greater vegetative vigor on average, with own-rooted, Salt Creek, 110R,
Freedom, and 41B exhibiting the lowest. Vines grafted to 3309C, Schwarzmann,
1103, St. George, and 5BB tended to have the highest vegetative vigor on average
when grown on soil pH 6, while own-rooted, 99R, Riparia Gloire, 4IB, and Bomer
tended to have the lowest at this same pH level.
In general, trends from this study show that over the range of the three soil
pH levels, vines grafted to rootstocks 3309C, 5BB, and 125AA consistently ranked
among the highest overall for vegetative vigor as defined by the majority of the
parameters measured. Conversely, own-rooted vines, as well as those grafted to
Bomer and Riparia Gloire, consistently ranked among the lowest.
As expected, vines growing in soil pH 4 were consistently lowest for all
Carbohydrate reserves showed no significant treatment effect.