Harsh Tiwari

Over a span of two years, a study on Barbera explored the interactive effects of localized cluster nebulization compared to uncooled vines, alongside the presence or absence of late basal leaf removal, using a full factorial design. In this design, basal leaf removal was implemented in both cooled and uncooled vines. The cooling system employed foggers that delivered a water flow of 11.2 L/h, automatically activating when air temperature exceeded 33 °C and relative humidity dropped below 55%. Throughout both seasons, assessments were made on leaf gas exchange, water status, yield components, and grape composition at harvest. In 2025, additional measurements included cluster temperature, soil water potential, and the evaluation of nebulized water dripping onto the soil. While the presence or absence of basal leaf removal had a minor effect on the gas exchange of the immediately upper leaves, leaf function was positively influenced by cooling in both seasons. In 2025, a direct correlation between cooling and non-limiting pre-dawn water potential was established. On average, the presence of basal leaves around the cluster reduced their temperature by 3–4 °C, while nebulization achieved up to 12 °C of cluster cooling. Late basal defoliation had minimal impact on must composition. Conversely, cooling did not affect yield per vine but resulted in higher malic acid at harvest and significantly reduced the concentration and content of total anthocyanins and phenolics compared to uncooled vines. In the absence of cooling, maintaining leaves around the cluster is crucial for controlling sunburn. This study highlights two main and novel findings: (i) the impact on final grape composition can vary depending on how cluster cooling is achieved (e.g., through simple shading or berry wetting), particularly concerning berry pigmentation; (ii) under the chosen activation conditions, under the row soil management and weather and soil characteristics, the irrigation system effectively serves a dual function: providing the expected cooling and enhancing soil moisture with consequent benefits for leaf physiology.

The increasing demand for low-alcohol wine products calls for effective vineyard strategies to reduce grape sugar concentration, while climate change is exacerbating sugar accumulation through warmer growing conditions. In this context, severe shoot trimming applied at specific phenological stages may represent a promising approach to induce sustained source limitation. A field experiment was conducted in 2025 on Vitis vinifera L. cv. Ortrugo to evaluate severe shoot trimming performed at the onset of berry softening. Vine growth, yield components, grape composition, and seasonal total soluble solids (TSSs) were monitored. Vine carbon reserves and shoot fruitfulness were assessed to evaluate carry-over effects. Experimental wines were produced to determine alcohol and fermentative aroma. Severe trimming markedly reduced leaf area and vine balance, leading to a sustained reduction in sugar accumulation. At harvest, grape TSSs decreased by 4.1 °Brix (17.6 vs. 21.7 °Brix) and the final wine alcohol concentration was lower by 3.4% (v/v). Yield was unaffected and no substantial negative effects on wine fermentative aroma were observed, while titratable acidity slightly increased. Even if trimming reduced winter starch concentration in roots, no reduction in shoot fruitfulness was observed in the subsequent spring. Severe trimming successfully reduced grape sugar and wine ethanol without compromising yield, aroma, or vine performance, supporting its potential for low-alcohol wine production and reduced-impact dealcoholization.

Background and Aims: Climate change poses increasing issues to the rapid and successful establishment of new vineyards. In this study, conducted over two consecutive seasons on potted vines, we evaluated the effects of a synthetic potassium polyacrylate hydrogel (WS‐SH) and an organic‐based hydrogel (WS‐OH), both applied at transplanting, on vine water status, productivity, and fruit and wine composition, under progressive water deficit. These treatments were compared with a water‐stressed control (WS‐C) and a fully irrigated reference (WW‐C). Methods and Results: In both years, WS‐SH and WS‐OH treatments delayed the decline in predawn water potential by several days and improved leaf gas exchange under limited irrigation. This led to increased leaf area and overall vine vigor. By the end of the second year, WS‐OH had greater root system development compared to all other water‐stressed treatments (+17% than WS‐C), while WS‐SH favored dry matter allocation toward aboveground organs (+17.6%). As a result, both WS‐SH and WS‐OH vines maintained yields comparable to WW‐C, whereas WS‐C showed a 33% yield reduction. Due to higher crop loads, WS‐SH and WS‐OH vines had lower leaf‐to‐fruit ratios than WS‐C (−0.116 m ² /kg and −0.147 m ² /kg, respectively), resulting in reduced grape sugar content (−1.8 and −1.6°Brix, respectively), anthocyanins (−48% and −51%, respectively), and phenolics (−21% and −23%, respectively). Wines produced at the end of the second season reflected this composition, showing significantly lower alcohol content (−1.11% v/v and −1.05% v/v, respectively), phenolic levels, and chromatic traits. Conclusions: Our results demonstrate that hydrogels applied at transplanting can enhance vine tolerance to water stress and increase yield in the first productive season, in exchange for a reduction in sugar and anthocyanin contents in grapes. Significance of the Study: Hydrogels could represent valuable tools to increase vineyard tolerance to summer stresses after transplanting. No substantial differences were observed between the effects of the synthetic and organic hydrogels, highlighting the potential of organic formulations as a sustainable and effective strategy to improve vineyard resilience to summer drought conditions. These results should be confirmed under operational conditions through field experiments.

In plants, proline acts as a compatible osmolyte with multiple stress-related functions, contributing to cell turgor regulation and the dissipation of excess energy. In this study, the use of a proline-rich yeast derivative (SYD) on pot-grown grapevines cv. Chardonnay was tested as a priming strategy to enhance vine water status and water deficit tolerance. Well-watered control vines were compared to those subjected to reduced irrigation at 80% of daily evapotranspiration for 43 days, with and without foliar SYD applications. Additionally, a group of vines received only 40% of daily evapotranspiration (ET) along with foliar SYD applications. The soil moisture content clearly mirrored the three irrigation levels (full water, 80% ET, and 40% ET). However, considering vines kept at 80%ET, SYD-treated vines had a consistently higher midday leaf water potential than controls (+0.22 MPa on Day of Year—DOY—214). SYD-treated vines kept at 80% ET and control vines at 100% ET exhibited similar stomatal conductance and assimilation rates (0.24 vs. 0.25 mol m⁻² s⁻¹, and 14.9 vs. 15.3 μmol m⁻² s⁻¹ on average from all measurements), while control vines kept at 80% ET lagged behind SYD-treated vines at 80% ET. On July 20th (DOY 201), in SYD-treated vines kept at 80% ET, leaves accumulated nearly twice the proline concentration compared to control vines receiving the same irrigation (17.7 vs. 10.6 µmol/g). Treated vines kept at 40% ET had stomatal conductance and leaf assimilation rates comparable to control vines at 80% ET (0.17 vs. 0.20 mol m⁻² s⁻¹ and 11.7 vs. 11.5 μmol m⁻² s⁻¹ on average). At harvest, the average yield of SYD-treated vines kept at 80% ET was similar to fully watered control vines maintained at 100% ET (1.75 vs. 1.82 kg), but showed higher soluble solids concentrations (20.9° Brix, vs. 19° Brix in fully watered control vines) and lower average titratable acidity (6.62 g/L vs. 7.7 g/L in fully watered control vines), while no differences were observed in the average titratable acidity between control vines kept at 80% ET and SYD-treated vines kept at 40% ET (6.15 g/L). Proline-rich SYD increased endogenous leaf proline levels and vine water status, also interacting with H₂O₂ accumulation, and resulted in long-term better physiological functioning at comparable water availability. The applications improved grapevine productive performance, effectively mitigating the negative impacts of reduced irrigation.

Vineyard sustainability increasingly focuses on transitioning from traditional soil management practices, such as tillage and herbicides, to environmentally friendly methods like cover cropping and mulching. While this strategy works in cool climates with abundant rainfall, its application in warmer areas is not advisable due to potential disadvantages, such as water and nutrient competition from cover crops, which may outweigh the benefits. We examine the pros and cons of vineyard tillage, including data on evaporation rates from wet and dry tilled soils. We explore methodologies to quantify competition between vine roots and grass roots, focusing on distinguishing native versus spontaneous vegetation, duration and extent of cover cropping, species used in sown mixtures, and cover crop water use rates. Novel soil management practices are discussed as alternatives to traditional green manuring, such as mid-row rolling and sub-row sward mulching. The review updates recent approaches for establishing native or sown under-vine cover crops, which, with irrigation, might control native weeds while colonizing shallow soil, allowing grapevine roots to penetrate deeper, moistened soil layers. Promising grasses include creeping species such as Glechoma hederacea, Trifolium subterraneum, and Hieracium pilosella. Finally, we describe three soil management protocols: two suited to dry farm conditions and one involving blue water availability, which may mitigate cover crop competition for water and nutrients while maintaining benefits such as reduced soil erosion, increased soil organic matter, carbon sequestration, and improved machinery access.

The success of double cropping in Vitis vinifera L. cultivated in temperate climates relies on bud forcing efficiency, which requires the prompt unlocking of apical dormant buds with sufficient fruitfulness. Chemical dormancy-breaking strategies need to be tested to enhance dormant bud forcing in summer pruning, as hydrogen cyanamide, the most used agent, could damage green organs. This study tested whether foliar applications of cytokinins and auxins could modulate dormancy release, potentially affecting bud forcing dynamics and shoot fruitfulness. The forcing treatments involved trimming primary shoots at the eighth node, removing lateral shoots, and retaining the main leaves and inflorescences. Five treatments were investigated: unforced control, control + 6-Benzyladenine application, forcing (FR), forcing + 6-Benzyladenine application (FBA), and forcing + Naphthaleneacetic acid application (FNAA). Phenological evolution, vegetative and productive parameters, and physiological characteristics have been assessed. Results showed that among the forcing treatments, FBA showed the highest forced/primary shoots ratio (106%), followed by FR (94%) and FNAA (21%). Primary yields were similar across treatments (2.74 kg), but total yield was highest in FBA (4.78 kg, including 2.02 kg from forced grapes), followed by FR (3.62 kg, with 1.09 kg forced). FNAA yielded no forced crop. During forced grapes maturation, photosynthesis rates were higher in forced leaves (11.1 μmol m⁻² s⁻¹, as FR and FBA average) than primary leaves (−32%). Forced grapes ripened 47 days later and achieved higher sugar content (21.7 °Brix) and titratable acidity (10.6 g/L) than primary grapes. The findings suggest cytokinins application enhances bud forcing, supporting the feasibility of double cropping, while auxins limited it.