X-ray imaging of 30 year old wine grape wood reveals cumulative impacts of rootstocks on scion secondary growth and Ravaz index

Abstract

Summary Annual rings from 30 year old vines in a California rootstock trial were measured to determine the effects of 15 different rootstocks on Chardonnay and Cabernet Sauvignon scions. Viticultural traits measuring vegetative growth, yield, berry quality, and nutrient uptake were collected at the beginning (1995 to 1999) and end (2017 to 2020) of the lifetime of a vineyard initially planted in 1991 and removed in 2021. X-ray Computed Tomography (CT) was used to measure ring widths in 103 vines. Ring width was modeled as a function of ring number using a negative exponential model. Early and late wood ring widths, cambium width, and scion trunk radius were correlated with 27 traits. Modeling of annual ring width shows that scions alter the width of the first rings but that rootstocks alter the decay of later rings, consistently shortening ring width throughout the lifetime of the vine. Ravaz index, juice pH, photosynthetic assimilation and transpiration rates, and instantaneous water use efficiency are correlated with scion trunk radius. Ultimately, our research indicates that rootstocks modulate secondary growth over years, altering physiology and agronomic traits. Rootstocks act in similar but distinct ways from climate to modulate ring width, which borrowing techniques from dendrochronology, can be used to monitor both genetic and environmental effects in woody perennial crop species.

Terroir and rootstock effects on leaf shape in California Central Valley vineyards

“…At this location, we have analyzed historical data showing that rootstock choice can modulate yield and vegetative biomass, and even more strongly Ravaz index (the ratio of yield to vegetative biomass) by almost up to 100% (Migicovsky et al, 2021). At the end of 30 years of production at this site, we analyzed the dendrochronology of scion trunk segments using X-ray Computed Tomography, showing that underlying the effects on Ravaz index, rootstocks had altered secondary patterning of the vasculature, and likely the hydraulic performance, of the scion continuously over the life of the vineyard (Migicovsky et al, 2023). Both the effects of rootstocks on Ravaz index and secondary patterning are strongly additive and robust: that is, regardless of scion properties or environmental effects, rootstocks consistently add or subtract from scion trait values.…”

“…showing that underlying the effects on Ravaz index, rootstocks had altered secondary patterning of the vasculature, and likely the hydraulic performance, of the scion continuously over the life of the vineyard (Migicovsky et al, 2023) 1), suggests that leaf shape is not a mechanism affecting plant physiology. Nonetheless, we detect clear changes in leaf shape, orthogonal to genetic differences that define varieties, that arise from effects of rootstocks and location (Figures 2, 3, 4, and 6).…”

“…The vineyard location sampled in San Joaquin is described in detail in Migicovsky et al (2021; 2023). Due to differing vineyard orientations, leaves were collected from either the north- or west-facing side of the vine.…”