The moment of preharvest elicitor application influence its final effect on winegrapes quality
Abstract
Phenolic compounds are secondary metabolites of grapes. Plants produce a wide variety of this type of metabolites through diverse biosynthesis pathways and their production is sometimes a response to external stimuli, either environmental or biotic stresses. Some of them may act as chemical defenses against pathogens or herbivores and their synthesis is increased when the attack exists. However, it is remarkable that the synthesis of these interesting compounds can be activated even when the stimulus is not present, with the use of elicitors. These are substances that when applied exogenously trigger the biosynthetic pathways conducting to the synthesis of these defense compounds. Several studies have already demonstrated that the mechanism involved in the response of the plant after the use of elicitors implied an increased concentration of polyphenol compounds. In winegrapes, the elicitors are usually applied at veraison and the application is repeated some days after the first application. However, our studies showed that, when the evolution of phenolic compounds of the elicitor treated-grapes was followed during all the ripening period, the maximum concentration of phenolic compounds was achieved around two weeks after the treatment, decreasing from this moment and up to the harvest date. Therefore, we planned, for the first time, the application of the elicitor not at veraison but two weeks before the estimated harvest date and the phenolic content of these grapes at harvest were compared with control grapes (no elicitor treatment) and with grapes treated with the elicitor applied at veraison. The results showed that the treatment of grapes two weeks before harvest generally led to better results as regard the phenolic composition of grapes. The effect on the different phenolic families (mainly anthocyanins and tannins) are discussed as well as the differences found in the corresponding wines.
Issue: Macrowine 2016
Type: Poster
Authors
*University of Murcia