A Polish study reveals that vines grown with 50% less fertilizer produce wines richer in aromatic compounds
The dryland trial found more volatile compounds in the wine of a Polish variety.
Friday, September 18, 2026
A study published this Thursday, September 17, in the scientific journal OENO One suggests that combined mycorrhizal inoculation, applied alongside a 50% reduction in mineral fertilization, can increase the aromatic potential of the must and the total amount of volatile compounds in the wine of the Vitis vinifera 'Danmarpa Polonia' grape variety. The work, authored by Marcin Kolasiński, Mariusz Dziadas, and Joanna Bykowska, was conducted over five years under dryland conditions in Poland.
This finding is of interest to the wine sector because it connects three elements that are increasingly important in vineyards: the use of microorganisms in the field, the reduction of inputs, and the aromatic quality of the grapes and the wine. If this effect is replicated in other varieties and regions, it could help adjust fertilizer use without compromising sensory profile and even improve it in some cases.
The trial was conducted between November 2018 and August 2023 at the experimental station of the Poznań University of Life Sciences in western Poland, on an irrigation-free farm that relied solely on rainfall. Researchers worked with 120 plants divided into five treatments, each with three replicates of eight strains. They compared inoculation with a commercial ectomycorrhizal preparation, inoculation with arbuscular mycorrhizal fungi, a combination of both, a control with full mineral fertilization, and a second control with fertilization reduced to 50% but without inoculation.
The variety analyzed, 'Danmarpa Polonia', is a Polish selection very close to the Hungarian grape 'Pannonia Kincse' or 'Skarb Panonii'. The authors clarify that they are using the local name under which it was being evaluated. They also emphasize an important point regarding the study design: in the ectomycorrhizal treatment, a commercial inoculant with selected fungal and basidiomycete isolates was used, but the actual root colonization was not independently quantified, either by microscopy or molecular methods. Therefore, they urge caution in interpreting this part of the trial as confirmed ectomycorrhizal symbiosis in grapevines.
The samples for aromatic analysis were taken in the third and fourth campaigns after planting, i.e., in 2021 and 2022. The 2023 campaign was excluded from the volatile compound analyses because the plants suffered a severe infestation of powdery mildew, Erysiphe necator, within a low-intervention management system, which prevented obtaining a representative harvest.
In the 2021 musts, the team identified nine free volatile compounds: two C6 aldehydes, three C6 alcohols, and four monoterpene alcohols. The most abundant compounds were 1-hexanol, (E)-3-hexen-1-ol, (E)-2-hexen-1-ol, and geraniol. The highest overall abundance was observed in the combined inoculation treatment, followed by arbuscular inoculation and inoculation with the ectomycorrhizal preparation. The control with complete mineral fertilization showed the lowest overall signal.
The 2021 data show clear differences between treatments. The must from the combined treatment reached 78.48 µg/L equivalents of (E)-3-hexen-1-ol, compared to 1.64 µg/L in the fully fertilized control. For geraniol, the same treatment reached 23.01 µg/L, while the fully fertilized control remained at 4.78 µg/L. In contrast, the isolated arbuscular inoculation showed the highest values for some specific compounds, such as 1-hexanol, with 40.67 µg/L, and (E)-2-hexen-1-ol, with 15.01 µg/L. All comparisons by compound yielded adjusted p-values <0.001.
The same general pattern emerged in 2022, and in that campaign, the article also provides the total sum of free volatiles in must. The combined treatment reached 141.14 µg/L equivalents. Far behind were arbuscular inoculation, with 76.87 µg/L; inoculation with the ectomycorrhizal preparation, with 45.53 µg/L; the control with reduced fertilization without inoculation, with 27.04 µg/L; and the control with full fertilization, with 16.32 µg/L.
Within that second campaign, the combined treatment again stood out for its concentration of compounds linked to varietal aroma. It reached 51.25 µg/L equivalents of (E)-3-hexen-1-ol and 27.93 µg/L of geraniol. It also registered the highest values for (E)-2-hexenal, citronellol, and nerol. Arbuscular inoculation alone yielded the highest averages for 1-hexanol and (E)-2-hexen-1-ol, although in the case of 1-hexanol, there was no difference compared to the combined treatment. Again, all differences by compound had an adjusted p-value less than 0.001.
The study also analyzed bound aromatic precursors in the must—compounds that are not directly perceived but can release odor molecules during fermentation or aging. Following enzymatic hydrolysis, the researchers consistently released six volatile aglycones: 1-hexanol, (E)-3-hexen-1-ol, (E)-2-hexen-1-ol, α-terpineol, citronellol, and geraniol.
In 2021, the combined treatment again led the way in this group of precursors. It reached 14.90 µg/L equivalents of 1-hexanol, 17.60 of (E)-3-hexen-1-ol, 16.10 of (E)-2-hexen-1-ol, 17.90 of α-terpineol, 15.50 of citronellol, and 15.80 of geraniol. Treatments with arbuscular inoculation alone and with full fertilization occupied an intermediate position, while inoculation with the ectomycorrhizal preparation and the control with reduced fertilization and no inoculation had the lowest levels. Here too, the authors report adjusted p-values below 0.001.
Beyond the must, the article notes that wines produced from the combined treatment showed higher total volatile concentrations than the fully fertilized control. Principal component analysis clearly separated the vines subjected to dual inoculation from the control treatments, a statistical indication that the chemical profile of the must and wine changed consistently under this management strategy.
The biological basis used by the authors is well-known in grapevines, particularly for arbuscular mycorrhizae. The scientific literature cited in the study indicates that these associations can improve nutrient absorption, modify root architecture, help the plant during periods of water scarcity, and influence metabolic pathways related to terpenes and other secondary compounds. This is relevant to the aroma of grapes and wine because many compounds appear both in free form and bound to sugars. During fermentation and aging, these bound compounds can break down and release monoterpenes and norisoprenoids, which alter the final aromatic profile.
The study was conducted in a temperate climate zone in western Poland, with moderately warm summers, cold winters, and an average annual rainfall of between 550 and 600 mm. This detail is important because the vineyard was dry-farmed throughout the trial. In this type of management, any tool that improves nutrient use efficiency and maintains grape quality is of direct interest to wineries and input suppliers.
The authors note, however, that the grapevine's response to mycorrhizae depends on the fungus used, the soil, the rootstock, the variety, and the crop load. They also emphasize that in vineyards, natural root colonization usually involves several species simultaneously. Therefore, although the results open a path toward reducing mineral fertilization and modifying the aromatic profile, interpreting the treatment with an ectomycorrhizal inoculant requires caution until actual root colonization is verified.