EMERGE

D.D. del MUR n. 104 del 02/02/2022

Codice progetto MUR: 2022SCAN2Z

CUP: J53D23010430001

Sostegno finanziario UE: 123.734,00 €

Durata: 12/10/2023 - 11/10/2025

Coordinatore di progetto: Università degli Studi di Bologna

Ruolo UNIBO: PI

Responsabile Scientifico: Elena Baldi

Gruppo di ricerca: Elena Baldi, Chiara Pastore, Moreno Toselli, Ilaria Filippetti, Gianluca Allegro, Gabriele Valentini, Francesco Spinelli

Ambiti di ricerca: Arboricoltura

Abstract

The transition toward sustainable and circular agricultural systems is a major challenge for modern viticulture. The wine industry generates large quantities of organic residues, including winery sludges and by-products from wastewater treatment; although these materials are often classified as waste, they actually contain substantial levels of organic matter and nutrients, making them potentially valuable resources. The PRIN project EMERGE (From farm to glass: use of a winemaking waste-derived compost as fertilizer for grapevine plants. Elucidation of the interaction between vine molecular response and microbial community for wine production) investigated the potential of a compost derived from winery sludge (WSC) as an alternative to conventional mineral fertilization in grape.

The project aimed to evaluate the agronomic, physiological, microbiological, and molecular effects of WSC application in vineyards and to understand how organic fertilization influences plant–microbe interactions, grapevine performance, and grape quality. To achieve these objectives, a two-year pot experiment with Cabernet Sauvignon vines and a long-term field trial with Sangiovese vines were conducted. The study integrated plant physiology, soil chemistry, microbial ecology, metataxonomic analyses, transcriptomics, metabolomics, and grape quality assessments. This multidisciplinary approach allowed the investigation of the mechanisms through which compost-derived fertilization affects soil health, microbial communities, grapevine metabolism, and final production traits.

Objectives and Purpose

The main objective of EMERGE is to investigate the potentialities of using winemaking wastes-derived compost as a sustainable technique to improve vine nutrition in relation to the development of a beneficial microbial community in wine making. EMERGE will be to highlight the role of compost in:

· affecting the molecular response of vines;

· modifying microbial community on plants and soil;

· influencing the autochthonous berry microbiome and its effect on spontaneous fermentation;

· improving soil biological fertility parameters and the ecosystem services provided by the soil microbial community;

· enhancing soil carbon sequestration in the context of climate change and circular economy.

The investigation of the above-mentioned aspects will be tackled by adopting a multidisciplinary approach and a multi-level experimental design, characterised by different degrees of complexity (short and long-term effect of treatment with compost), to cover all the winemaking stages “from farm to glass”.

Expected results

Results obtained within EMERGE will bridge the gap of knowledge on compost utilisation, exploring all the aspects re-lated to its effects on soil fertility and microbial ecology, on physiology of plant nutrition, on the molecular responses of vines and finally on wine quality. The results of EMERGE will also give a clear picture of the complex dynamics of soil microbiome, with a particular attention to the microorganisms that mostly affect vine growth and productivity. A better knowledge of these processes will contribute to the development of better nutrient management strategies.

Achieved results

The project demonstrated that winery sludge compost is a sustainable and effective alternative to mineral fertilization. In both pot and field experiments, WSC improved grapevine physiological performance, maintaining chlorophyll content, photosynthetic activity, and plant nutritional status at levels comparable to or higher than conventional fertilization. Compost-treated plants frequently exhibited enhanced stomatal conductance and improved physiological responses during periods of environmental stress, indicating a positive effect on plant resilience. Nutritional analyses showed that WSC efficiently supplied essential nutrients, particularly nitrogen, phosphorus, and potassium. Compost-treated vines maintained yields comparable to those obtained with conventional mineral fertilization, while showing improved vine nutritional status and physiological performance. Grape quality parameters, including soluble solids, acidity, and pH, remained within the optimal range for winemaking. Furthermore, WSC application positively influenced berry composition, leading

in several cases to higher anthocyanin concentrations and improved phenolic potential. Small-scale vinification trials demonstrated that the use of compost did not negatively affect wine quality, confirming the suitability of this fertilization strategy for sustainable wine production. These results confirm the capacity of winery-derived compost to provide a gradual and effective nutrient release while reducing reliance on synthetic fertilizers.

One of the most important achievements concerned soil quality. Compost application significantly increased soil microbial biomass and enhanced soil carbon accumulation, indicating improved soil fertility and organic matter content even in the short period. The availability of key nutrients, including nitrate, phosphorus, and potassium, was generally higher in compost-amended soils, reflecting more active nutrient cycling processes.

The biological activity of soil was strongly stimulated by WSC application. Activities of enzymes involved in carbon, nitrogen, phosphorus, and sulfur cycling (including β-glucosidase, urease, phosphatases, and arylsulfatase) were consistently higher in compost-treated soils than in mineral-fertilized or unfertilized controls. These results demonstrate that compost promotes a more biologically active soil environment capable of sustaining nutrient turnover and ecosystem functionality. Furthermore, compost enhanced the metabolic activity and functional diversity of rhizosphere microbial communities. WSC-treated soils showed higher microbial activity and a broader utilization of carbon substrates, suggesting the development of more versatile and efficient microbial populations.

Metataxonomic analyses further confirmed that compost application significantly modified both bacterial and fungal community composition. Rhizosphere communities associated with WSC were enriched in microorganisms known for plant growth promotion, nutrient mobilization, biocontrol activity, and tolerance to abiotic stress. Fungal communities showed a greater abundance of taxa involved in organic matter decomposition and nutrient cycling. These findings indicate that compost application promotes beneficial microbial communities that contribute to soil fertility and plant health.

Transcriptomic profiling identified a range of molecular responses in both root and berry tissues. Root RNA-seq identified thousands of differentially expressed genes in compost-treated plants, particularly at flowering. Functional enrichment analyses highlighted pathways related to cell wall remodeling, transcriptional regulation, stress responses, antioxidant activity, and secondary metabolism. Genes involved in stilbene and resveratrol biosynthesis were significantly modulated, suggesting activation of defense-related mechanisms and enhanced adaptation to environmental conditions.

Berry transcriptomic analyses showed that fertilization strategy influenced gene expression associated with ripening, transport processes, hormone metabolism, defense responses, and secondary metabolite biosynthesis. In particular, pathways related to phenylpropanoid metabolism, flavonoid synthesis, and stilbene production were affected by compost application. These results indicate that organic fertilization can modulate berry metabolic processes with potential implications for grape and wine quality.

The integration of microbial and transcriptomic datasets provided evidence that compost-induced changes in the rhizosphere microbiome are associated with specific grapevine molecular responses. This represents one of the most innovative outcomes of the project, demonstrating a functional link between organic fertilization, microbial community dynamics, and plant gene expression.

Overall, the EMERGE project demonstrated that compost derived from winery sludge can successfully replace conventional mineral fertilizers while improving soil health, stimulating beneficial microbial communities, and modulating grapevine physiological and molecular responses. The results provide strong scientific evidence supporting the valorization of winery waste amendments within a circular economy framework and highlight the potential of organic amendments as key tools for sustainable and climate-resilient viticulture.