Uncovering the effects of kaolin on balancing berry phytohormones and quality attributes of Vitis vinifera grown in warm-temperate climate regions

Abstract

Research ArticleReceived: 22 December 2020 Revised: 6 April 2021 Accepted article published: 5 July 2021 Published online in Wiley Online Library:(wileyonlinelibrary.com) DOI 10.1002/jsfa.11413Uncovering the effects of kaolin on balancingberry phytohormones and quality attributesof Vitis vinifera grown in warm-temperateclimate regionsSara Bernardo,aLia-Tânia Dinis,aNelson Machado,bAna Barros,aMarta Pitarch-Bielsa,cAureliano C Malheiro,aAurelio Gómez-Cadenascand José Moutinho-Pereir aa*AbstractBACKGROUND: The application of kaolin particle lm is considered a short-term strategy against several environmental stres-ses in areas with a Mediterranean-like climate. However, it is known that temperature uctuations and water availability overthe season can jeopardize kaolin efciency in many Mediterranean crops. Hence, this study aims to evaluate the effects of kao-lin foliar application on berry phytohormones, antioxidant defence, and oenological parameters at veraison and harvest stagesof Touriga-Franca (TF) and Touriga-Nacional (TN) grapevines in two growing seasons (2017 and 2018). The 2017 growing sea-son was considered the driest (−147.1 dryness index) and the warmest (2705 °C growing degree days) of the study.RESULTS: In 2017, TF kaolin-treated berries showed lower salicylic acid (−26.6% compared with unsprayed vines) and abscisicacid (ABA) (−10.5%) accumulation at veraison, whereas salicylic acid increased up to 28.8% at harvest. In a less hot season, TNand TF kaolin-treated grapevines showed a twofold in ABA content and a threefold increase in the indole-3-acetic acid contentat veraison and lower ABA levels (83.8%) compared with unsprayed vines at harvest. Treated berries showed a decreased sugarcontent, without compromising malic and tartaric acid levels, and reactive oxygen species accumulation throughout berryripening.CONCLUSION: The results suggest kaolin exerts a delaying effect in triggering ripening-related processes under severe summerstress conditions. Treated berries responded with improved antioxidant defence and phytohormone balance, showing signif-icant interactions between kaolin treatment, variety, and developmental stage in both assessed years.