Diego Tomasi

Grape-associated microbial communities are key contributors to wine quality and microbial terroir, yet their dynamics during withering, a critical post-harvest stage for premium sweet and fortified wine production, remain poorly characterized. Using high-throughput metabarcoding (16S rRNA and ITS), we monitored bacterial and fungal communities on Corvina grape berries throughout withering under controlled (C) and non-controlled (NC) dehydration conditions, integrating microbiome data with previously determined volatile organic compound (VOC) and stilbene profiles to uncover taxon–metabolite relationships. Microbial communities underwent progressive restructuring during dehydration. Moreover, the two withering conditions exhibited distinct dehydration kinetics, with C reaching 30% weight loss 14 days earlier than NC, with a significant effect on the abundance of several wine-relevant and spoilage-associated taxa. Metschnikowia was significantly more abundant under C conditions at 10% and 20% weight loss, while Botrytis reached 26.5% relative abundance at 30% weight loss under NC compared with 2.4% under C. A correlation network analysis identified significant associations between Lactobacillus, Acinetobacter, Clostridium, and metabolite accumulation, with Metschnikowia showing positive associations with bioactive compounds and negative associations with spoilage fungi. This first joint time-course analysis of mycobiome and bacteriome dynamics alongside metabolome changes during withering highlights significant associations between microbial succession and grape biochemical changes during withering.

Spatial variability in vine vigour and yield components is a major challenge for vineyard management and consistent grape quality, particularly in hilly landscapes. This study evaluates the impact of on-the-go variable-rate fertilisation (VRA) in reducing within-vineyard variability in an 8.5 hectares commercial vineyard in the Conegliano Valdobbiadene Prosecco DOCG region (Italy). Over two growing seasons, a proximal NDVI sensor (GreenSeeker) guided real-time fertiliser applications without prescription maps. Vine vigour, yield components, and grape quality were evaluated using geostatistical analysis and coefficient of variation (CV) metrics. VRA reduced total spatial variability (sill) by 55% and erratic variance (nugget effect) by 39% for NDVI measurements. Variability in yield components also decrease (−21.1% for cluster number, −6.25% for cluster weight), while grape composition parameters (total soluble solids, titratable acidity, and pH) was not significantly altered despite a slightly higher variability (in titratable acidity and pH), indicating that fertiliser modulation did not compromise grape quality. Nitrogen input was reduced by 50%, highlighting economic and environmental benefits (−302 kg CO₂). These results show that simplified, sensor-based, on-the-go VRA is a practical and sustainable precision viticulture tool, even in small and heterogeneous vineyards typical of the Conegliano Valdobbiadene Prosecco DOCG area.

Sentinel-2 (S2) is widely considered a reliable satellite constellation for monitoring several crops, such as grapevine (Vitis vinifera L.). A large dataset of Italian vineyards randomly chosen was monitored with S2 from 2017 to 2022. Two vegetation indices (VIs) and their statistics were calculated from each vineyard. In addition, structural features and topographic information were assessed using Google Earth and national databases. The research study aims to identify the most relevant drivers of spatial variability by assessing the VIs among the whole dataset and the within-vineyard variability. The latitude and the vintage showed the most relevant effect on spatial variability, depicting the effect of daylight hours, climate conditions and weather events. However, the vintage did not affect the patterns of the within-field variability. Regarding grapevine management, training systems and the rows’ orientation were relevant boosters of variability. While the vineyards planted with north–south-oriented rows reached the highest VIs values, the east–west-oriented ones showed the highest variability. Finally, an interaction effect was detected between hill or plain plantation and the terrain slope on both the average and variability of the VIs. The conclusions from the present study suggest the relevance of clustering vineyards under remote supervision according to the structural features to reduce data variability. Further studies should investigate other structural features or managerial properties.

This study examined the potential use of three bacterial strains—Paraburkholderia sp. strain CRV74, Pseudomonas sp. strain CRV21, and Acinetobacter sp. strain CRV19—as biocontrol agents of Botrytis cinerea in grapevine. These strains were selected for their ability to inhibit B. cinerea growth in vitro and used in field conditions for the control of grey mould symptoms in ‘Glera’ grapes. To this end, after inoculating these microorganisms onto plants sprayed with B. cinerea spores, the final yield, the physicochemical characteristics of the must, disease incidence, and the possible influence on the expression of plant-defence proteins were evaluated. Strain CRV21 resulted as being the most effective in combating grey mould (−20% of disease incidence). Although yield was not affected, significantly different values of total soluble solids content was observed. Additionally, a significant up-regulation of the genes PR-1, PR-5, β-1,3-glucanase, and class III chitinase was observed. These findings highlight the potential application of strains with anti-botrytis activity as sustainable alternatives to chemical defence for the control of this pathogen.

In a world grappling with the severe effects induced by climate change, one of the most significant concerns affecting agriculture is the gradual decline in water quality for irrigation associated with reduced rainfalls and the consequent increase in soil salinity. This issue is particularly crucial for grapevine cultivation (Vitis vinifera L.) and the associated winemaking industry. The aroma of the resulting wines and the yield parameters can be influenced both directly by water quality and indirectly due to the effects exerted by salinity on the microbiota, which directly impacts plant health. To gain insights into this topic, our study aimed to analyse the changes induced in the microbiota of both the rhizosphere and the carposphere due to salt stress using a metabarcoding approach, focusing on Vitis vinifera cv. Glera. The control plants were irrigated with rainwater, while the treated plants were irrigated with water containing salt (NaCl). Our findings revealed significant differences in the microbiota (both fungi and bacteria) of the rhizosphere and carposphere between the two treatments. For instance, the Shannon diversity index (i.e., alpha diversity) was lower in the treated plants compared to the control not-treated ones, whilst the beta diversity did not show any differences. Several microbial phyla exhibited better resilience to this abiotic stress (e.g., Ascomycota, Saccharomycetes, Acidobacteria, Proteobacteria, Bacteroidetes), shedding light on their impact on crucial bacterial and fungal groups essential for the subsequent winemaking stages. Additionally, the salt stress negatively affected the yield parameters. This study contributes valuable insights to the viticultural community, providing a deeper understanding of the complex interplay between soil characteristics, microbial communities, and their influence on productivity.

Several researchers stated that climate change effects are arising quickly in the Mediterranean region. Temperature increasing and droughty summers are two of the most common patterns threatening sparkling wines’ grape quality. The present study investigated nitrogen nutrition to enhance acidity and preserve the aromatic compound on Vitis vinifera var. Glera for producing white sparkling wine. Half of the one-hectare vineyard placed in northeast Italy was fertigated with nitrogen during summer, while the control half received only mineral fertilization in spring as usual in the area. The trial lasted three years. The grapes’ quality was monitored and compared at harvest. The statistical analysis proved an affordable trend among treatments in which the fertigated grapes showed, on average, more free amino acids (+32%), more yeast assimilable nitrogen (+71%), more acidity (+21%), and lower total soluble solids concentration (−3%) than the control grapes. Energy storage, fruit yield, and wood mass were measured too. The study proved the nitrogen supply did not affect either fruit yield or plant vigor. Therefore, nitrogen fertigation has been confirmed to be a reasonable growing practice to preserve wine’s aroma and acidity against climate change.

In the Valpolicella area (Verona, Italy) one of the most important Italian wines is being produced: Amarone, predominately made by Vitis vinifera cv. Corvina. This wine is subjected to a specific postharvest process, namely, withering, which aims to increase alcohol content and/or high residual sugars while retaining richness in aromas and organoleptic compounds. In accordance with guidelines and strict Amarone protocol set by the Consorzio of Amarone-Valpolicella, withering must be carried out by setting the grapes in a suitable environment. In our study, the withering process was performed following the traditional methods, i.e., in open-air, natural environmental conditions, as generally performed by winegrowers, leading to a weight loss in grapes of up to 30%. Whilst the effect of different postharvest conditions is clear and studied, it is interesting to know how soil can affect both grapes and wine profile, in terms of aromas, which are of great importance for this crafted wine. For this purpose, for two study years, the influence of two different sites (with regards to the carbonates’ content) on aromas were investigated. Furthermore, microvinifications and the sensory profile of the resulting wines were analysed. Our results clearly indicated that different soils’ characteristics, particularly differences in carbonate content, had an important effect, not only on the aromatic compounds of grapes and wines, but on the sensory profile as well. This information will help winegrowers and winemakers in the process of determining site selection for future vineyards in order to obtain a final optimum Amarone wine, in terms of its aromatic composition—one that is able to respond to the market demand.

Dormant cane pruning has a great impact on vineyard management both in terms of labour costs and the time required to complete this field operation in the absence of mechanisation. In this study, we investigated over three seasons the influence of five pruning dates on yield components, grape composition, phenology and carbohydrate reserves in the variety Merlot, grown in a warm climate area. Pruning was conducted soon after harvest, at the end of leaf fall, two bud dormancy stages and vine bleeding. Early pruning, carried out a few days after the grape harvest, did not significantly affect vine productivity or grape composition in the next season compared to full winter pruning. Similarly, non-structural carbohydrate concentration in trunk and roots showed no difference just before budburst, no matter the timing of pruning. Late winter pruning at vine bleeding slightly postponed budburst and flowering; it also delayed veraison in one out of two years of observation without affecting grape maturity. Our findings suggested that, in a warm-climate area where leaf fall occurs within a ten-week period after harvest, early pruning had no detrimental effects on reserve accumulation in storage organs and, therefore, in vine yield and grape composition in the next harvest, thus allowing viticulturists to operate winter pruning over an extended interval of time.