Exploring Seaweed and Glycine Betaine Biostimulants for Enhanced Phenolic Content, Antioxidant Properties, and Gene Expression of Vitis vinifera cv. "Touriga Franca" Berries

Climate change will pose a challenge for the winemaking sector worldwide, bringing progressively drier and warmer conditions and increasing the frequency and intensity of weather extremes. The short-term adaptation strategy of applying biostimulants through foliar application serves as a crucial measure in mitigating the detrimental effects of environmental stresses on grapevine yield and berry quality. The aim of this study was to evaluate the effect of foliar application of a seaweed-based biostimulant (A. nodosum-ANE) and glycine betaine (GB) on berry quality, phenolic compounds, and antioxidant activity and to elucidate their action on the secondary metabolism. A trial was installed in a commercial vineyard (cv. "Touriga Franca") in the Cima Corgo (Upper Corgo) sub-region of the Douro Demarcated Region, Portugal. A total of four foliar sprayings were performed during the growing season: at flowering, pea size, bunch closer, and veraison. There was a positive effect of GB in the berry quality traits. Both ANE and GB increased the synthesis of anthocyanins and other phenolics in berries and influenced the expression of genes related to the synthesis and transport of anthocyanins (CHS, F3H, UFGT, and GST). So, they have the potential to act as elicitors of the secondary metabolism, leading to improved grape quality, and also to set the foundation for sustainable agricultural practices in the long run.

Ascophyllum nodosum Extract and Glycine Betaine Preharvest Application in Grapevine: Enhancement of Berry Quality, Phytochemical Content and Antioxidant Properties

The Douro Demarcated Region (DDR) has peculiar edaphoclimatic characteristics that provide a suitable terroir for premium wine production. As climate change effects continue to emerge, ensuring productivity and quality becomes increasingly important for viticulturists, as those directly determine their profits. Cultural approaches, such as the use of biostimulants, are actively being developed to mitigate abiotic stress. The main objective of this work was to assess the effect of foliar sprays of a seaweed (Ascophyllum nodosum)-based extract (ANE) and glycine betaine (GB) on grape berry quality, bioactive compounds, and antioxidant activity. A trial was installed in a commercial vineyard (cv. 'Touriga Franca') in the Douro Superior (Upper Douro) sub-region of the Douro Demarcated Region. In 2020 and 2021, three foliar sprayings were performed during the growing season, namely at pea size, bunch closure, and veraison. There was a positive effect of both biostimulants (ANE and GB) on the physiological and biochemical performance of cv. 'Touriga Franca' exposed to summer stress. In general, the GB 0.2% spraying was the most promising treatment for this grape cultivar, as it increased berry quality, the concentration of bioactive compounds (total phenolics, flavonoids, and ortho-diphenols), and the antioxidant activity. These results revealed the efficacy of biostimulant sprayings as a sustainable viticultural practice, improving berry quality under summer stress conditions.

Effect of anti-hail net on production and quality of ‘Rose Niagara’ grapes grown in Serra Gaúcha region, south Brazil

In the Serra Gaúcha region, South Brazil, the occurrence of hail is common due to relief and the cold air currents coming from polar regions. Nowadays, the use of anti-hail nets to protect fruit production is increasing, but the real effects of using this coverture on vines are largely unknown. Thus, this work aimed to evaluate the impact of the use of an anti-hail net on the productivity and quality parameters of ‘Rose Niagara’ grapes grown in the region, in the 2019/2020 and 2020/2021 harvests. The studied parameters were production, number of bunches per plant, bunch length, berry diameter, mass of 100 berries, average bunch mass, juice pH, titratable acidity, soluble solids, phenolic compounds content, total anthocyanins content, and photosynthetically active radiation. The results showed that the anti-hail net influenced some quality parameters, but this change was not consistent in the two harvests, indicating a larger influence of edaphoclimatic conditions than of the use of the net. Thus, the anti-hail net may be an alternative to protect vineyards from hail and other bad weather conditions, without having important negative impacts on the production and quality of ‘Rose Niagara’ grapes.