Interactive effects of the rootstock and the deficit irrigation technique on wine composition, nutraceutical potential, aromatic profile, and sensory attributes under semiarid and water limiting conditions

Field-grown mature Monastrell grapevines grafted on five different rootstocks (140Ru, 1103 P, 41B, 110R, 161-49C) were subjected to regulated deficit irrigation (RDI) and partial root zone irrigation (PRI) in a semiarid region in SE Spain (D.O. Bullas, Region of Murcia). The main goal was to analyse the effects of the rootstock (R), irrigation method (IM), and their interaction (R x IM) on the final wine composition, volatile aromatic profile, and wine sensory attributes. The application of low annual water volumes (85-90 mm year(-1)) to low vigorous rootstocks (161-49C, 110R) was reflected in wines with higher contents of polyphenolics and alcohol, a higher wine quality index (QI(wine)), enhanced levels of health-promoting bioactive compounds (flavonols, malvidins), and better organoleptic perception compared to other rootstocks. These wines also had lower concentration of aromatic compounds (alcohols and esters). The 140Ru wines, although having a lower polyphenolic concentration and worse color, were among those rated most highly and preferred by the tasters. These wines had a high content of lactic acid and amino acids, higher tartaric/malic and anthocyanins/tannins ratios and a low concentration of aromatic compounds. In contrast, 1103 P and 41B wines had lower polyphenolic content-nutraceutical value, lower QI(wine), tartaric/malic and anthocyanins/tannins ratios, more aromatic compounds, abundant green-vegetable/astringent notes, and more defect-causing compounds. In addition, these wines were also the worst rated in the sensory analysis. Significant positive correlations between the polyphenolic content and alcoholic degree and the score in the wine sensory analysis indicated that the greater the polyphenolic and alcohol contents in the wine, the better valued and more preferred by the tasters it was. PRI method improved wine quality and organoleptic perception for low vigor rootstocks (especially 161-49C), compared to RDI. These wines showed darker color, higher sugar content and nutraceutical potential as well as better sensory perception compared to other rootstock-IM combinations. In contrast, for high vigor rootstocks (1103 P, 140Ru), RDI was more beneficial for wine composition, global quality, and sensory perception. Overall, the PRI method also increased the presence of some volatile unpleasant alcohols in the wines. We recommend the use of low vigor rootstocks and DI techniques with small water volumes to improve Monastrell wine quality, and as a measure to adapt vineyards to climate change under semiarid and water limiting conditions.