Effect of foliar application of Ca, Si and their combination on grape volatile composition

Abstract

Calcium (Ca) is an important nutrient for plants which plays key signaling and structural roles. It has been observed that exogenous Ca application favors the pectin accumulation and inhibition of polygalacturonase enzymes, minimizing fruit spoilage. Silicon (Si) is a non-essential element which has been found to be beneficial for improving crop yield and quality, as well as plant tolerance to diverse abiotic and biotic stress factors. The effect of Si supply to grapevine has been assessed in few investigations, which reported positive changes in grape quality and must composition. The aim of this work was to evaluate the influence of Ca and Si foliar treatments, applied either as single elements or in combination, on volatile composition of Tempranillo grapes. All treatments were applied twice, at veraison and one week later. The foliar applications were performed in triplicate, in a randomized block design. The volatile composition was determined in the musts by headspace solid-phase microextraction (HS-SPME) and subsequent analysis by GC-MS. Tempranillo is a neutral aromatic variety, for this reason, on this work we have focused on terpenoids and C₁₃ norisoprenoids, the two families most important regarding varietal aromas. Foliar application of Ca and Ca+Si enhanced p-cymene, geraniol, neral, and total terpenoids content in must with respect to control one. Ca+Si foliar treatment also improved limonene, α-terpineol, linalool, and nerol concentration in comparison with control must. Regarding C₁₃ norisoprenoids, Ca+Si foliar application was the only treatment that increased (E)-β-damascenone, (Z)-β-damascenone, β-cyclocitral, TDN, methyl jasmonate, and total C₁₃norisoprenoids with respect control must. Therefore, Ca+Si foliar application is a good tool to improve the varietal aromatic quality of Tempranillo grapes and it is economically feasible.

Acknowledgements: M. G.-L. thanks the UR for her Margarita Salas contract (European Union-Next GenerationEU). E.P. P.-Á. thanks the MICIU for her postdoctoral financial support (IJC2019-040502-I). Thanks to the company Tradecorp for supplying us with the silicon product.