Kaolin Application Modulates Grapevine Photochemistry and Defence Responses in Distinct Mediterranean-Type Climate Vineyards

• Main Authors: Sara Bernardo, Ana Luzio, Nelson Machado, Helena Ferreira, Vicente Vives-Peris, Aureliano C. Malheiro, Carlos Correia, Aurelio Gómez-Cadenas, José Moutinho-Pereira, Lia-Tânia Dinis
• Format: Article
• Language: English
• Published: MDPI AG 2021-03-01
• Series: Agronomy
• Subjects: foliar spray; heat stress; high light; JIP-test; particle-film; resilience
• Online Access: https://www.mdpi.com/2073-4395/11/3/477

At a local scale, kaolin particle-film technology is considered a short-term adaptation strategy to mitigate the adverse effects of global warming on viticulture. This study aims to evaluate kaolin application effects on photochemistry and related defence responses of <i>Touriga Franca</i> (TF) and <i>Touriga Nacional</i> (TN) grapevines planted at two Portuguese winegrowing regions (Douro and Alentejo) over two summer seasons (2017 and 2018). For this purpose, chlorophyll <i>a</i> fluorescence transient analysis, leaf temperature, foliar metabolites, and the expression of genes related to heat stress (<i>VvHSP70</i>) and stress tolerance (<i>VvWRKY18</i>) were analysed. Kaolin application had an inhibitory effect on <i>VvHSP70</i> expression, reinforcing its protective role against heat stress. However, <i>VvWRKY18</i> gene expression and foliar metabolites accumulation revealed lower gene expression in TN-treated leaves and higher in TF at Alentejo, while lipid peroxidation levels decreased in both treated varieties and regions. The positive kaolin effect on the performance index parameter (PI_ABS) increased at ripening, mainly in TN, suggesting that stress responses can differ among varieties, depending on the initial acclimation to kaolin treatment. Moreover, changes on chlorophyll fluorescence transient analysis were more pronounced at the Douro site in 2017, indicating higher stress severity and impacts at this site, which boosted kaolin efficiency in alleviating summer stress. Under applied contexts, kaolin application can be considered a promising practice to minimise summer stress impacts in grapevines grown in Mediterranean-like climate regions.