Research articleMalbec grape (Vitis vinifera L.) responses to the environment: Berry phenolics as influenced by solar UV-B, water deficit and sprayed abscisic acid

- We studied the effects of UV-B, water deficit and ABA sprays on Malbec berries.
- Previous incidence of UV-B prevented berry weight reduction and diminution of sugar.
- Water deficit and UV-B or water deficit and ABA, reduced the fruit yield.
- Irrespectively, UV-B increased astilbin, quercetin and kaempferol.
- ABA sprays increased anthocyanins, and phenolics with high ORAC.

High-altitude vineyards receive elevated solar ultraviolet-B (UV-B) levels so producing high quality berries for winemaking because of induction in the synthesis of phenolic compounds. Water deficit (D) after veraison, is a commonly used tool to regulate berry polyphenols concentration in red wine cultivars. Abscisic acid (ABA) plays a crucial role in the acclimation to environmental factors/signals (including UV-B and D). The aim of the present study was to evaluate independent and interactive effects of high-altitude solar UV-B, moderate water deficit and ABA applications on Vitis vinifera cv. Malbec berries. The experiment was conducted during two growing seasons with two treatments of UV-B (+UV-B and -UV-B), watering (+D and -D) and ABA (+ABA and -ABA), in a factorial design. Berry fresh weight, sugar content, fruit yield, phenolic compounds profile and antioxidant capacity (ORAC) were analyzed at harvest. Previous incidence of high UV-B prevented deleterious effects of water deficit, i.e. berry weight reduction and diminution of sugar accumulation. High UV-B increased total phenols (mainly astilbin, quercetin and kaempferol) and ORAC, irrespectively of the combination with other factors. Fruit yield was reduced by combining water deficit and high UV-B or water deficit and ABA. Two applications of ABA were enough to induced biochemical changes increasing total anthocyanins, especially those with higher antioxidant capacity.

Phenolic compounds were differentially elicited by sprayed abscisic acid, high solar UV-B and water deficit in Malbec berries of field-grown grapevines.137