Phenolic profile of grapevine cv. Tempranillo skins is affected by timing and severity of early defoliation

Aim of study: To investigate the effects three early leaf removal treatments on phenolic compounds cv. ‘Tempranillo’ (Vitis vinifera L.) grape skins.Area The experiment was conducted in a vineyard located Requena, Valencia (South-eastern Spain) over two consecutive seasons.Materials and methods: Four were investigated seasons drip-irrigated vines: Control (C), non-defoliated defoliation treatment, applied at different phenological stages intensities where all leaves from first 6 nodes eliminated just before flowering (ED) fruitset (LD). fourth treatment performed same time ED but only facing east eight removed (EED). At harvest, thirty-eight quantified by HPLC skins, including anthocyanins, flavanols, flavonols, hydroxycinnamic acids their tartaric derivatives.Main results: A general increase skin concentration found response to treatments. largest more significant observed for LD 2009 with relative increases respect un-defoliated vines 14.8, 86.0, 119.0, 75.9% flavonols hydroxycinnamates, respectively. On other hand, EED did not clearly modify any polyphenolic compound. In addition, families analyzed different. Malvidine derivatives altered treatments, while contents quercetin kaempferol ferulic coumaric acids, increased both years when applied.Research highlights: specific substances dependent timing, severity, season. Skin hydroxycinnamates most affected families.