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A study published on the oeno-one.com research platform by the University of Bordeaux shows for the first time the connection between the genetic characteristics of rootstocks and the mineral balance of the vines. Since the phylloxera catastrophe at the end of the 19th century, noble vines have mainly been grafted onto phylloxera-resistant rootstocks from American vines. These so-called rootstocks have a major influence on the uptake of water and minerals and modify the overall development of the plant. They play an important role in adapting to environmental conditions and are a major factor in maintaining the typical characteristics of the grape varieties.
The new study investigated the influence of genetically different rootstocks on the mineral content of the noble grapevine. To this end, the Cabernet Sauvignon, Pinot Noir, Syrah and Ugni Blanc varieties were grafted onto 55 genetically different rootstocks and planted near Bordeaux. In 2020 and 2021, leaf petiole analyses were used to measure the content of 13 minerals as well as shoot vigour, leaf chlorophyll content, bud fertility, yield and several other parameters at the time of berry ripening. The effects of magnesium deficiency or potassium excess were assessed visually for each plant and combined with the petiole analyses for the first time.
The researchers were able to prove that the rootstocks had a greater effect on the mineral content than the grape variety. The symptoms of magnesium deficiency also varied depending on the rootstock. As a result, the researchers modified the classification of rootstocks for the potassium and magnesium status of the noble grape varieties. This enables a more targeted choice of rootstocks for the respective soil properties and a more precise adjustment of fertiliser use. The study is the first to examine such a large selection of grafted rootstock varieties under natural conditions in a field trial.
(al / source: oeno-one)