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Water deficit and iron nutritional deficiency (iron chlorosis) are frequent environmental stresses affecting grapevine production in the Mediterranean region. The objectives of this work were (i) to study the combined effects of both stresses on aromatic profile of Tempranillo grapes, occurring simultaneously in the vineyard, and (ii) to evaluate the viability of foliar chlorophyll content at veraison (Chl) to early assess aromatic quality potential of grapes in those conditions. Twenty non-irrigated vineyard subzones (10 m × 10 m each), affected and non-affected by iron chlorosis, were monitored in Ribera del Duero Appellation of Origin (North-Central Spain) during two consecutive seasons. Factorial ANOVA was performed to study the effects of predawn leaf water potential and Chl measured at veraison on the must composition parameters and, specifically, on the concentrations of free and bound aromatic compounds. Water deficit tended to increase color intensity and extractable anthocyanin content of the grapes, whereas the incidence of iron deficiency enhanced total phenolic compound content within subzones with better water status. More water or iron stressed subzones restricted C 6alcohols contents than less stressed subzones. Without significant effects on vine vigor, yield or berry size, the incidence of iron chlorosis increased the concentrations of some specific terpenes, C 13-norisoprenoids, volatile acids and volatile phenols. These results showed that low to moderate iron stress can have positive effects on grape aromatic quality, and demonstrated that Chl can be a useful tool in precision viticulture to map the aromatic potential within rainfed vineyards affected by iron chlorosis.

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Background: Water deficit and iron deficiency (iron chlorosis) are common environmental stresses that affect grapevine production in the Mediterranean area. Studies on the impact of both stresses, when they act simultaneously, are rare. The main objective of this investigation was to evaluate the combined effects of the incidence of iron chlorosis and the vine water status on quality of Tempranillo wine. For this, 20 non-irrigated vineyard subzones (10 m × 10 m each), from non-affected to moderately affected by iron chlorosis, were monitored in the Ribera del Duero area (north-central Spain) during two consecutive seasons. Results: Factorial analyses of variance were performed to study the effects of predawn leaf water potential and foliar chlorophyll content, both measured at veraison, on chemical and sensory characteristics of wine. With an impact much greater than water status, the incidence of iron stress decreased pH of the wine and enhanced sensory attributes as tonality, layer intensity, flavour intensity, and persistence in the mouth. There were increases in red colour, astringency, and persistence of the wine associated with chlorosis, although they might be restricted in water-deficit conditions. Conclusion: The results have demonstrated that mild to moderate iron stress can have positive effects on chemical and sensory attributes of Tempranillo wine. Measurements of foliar chlorophyll content at veraison could be very useful to map quality potential in rainfed vineyards affected by iron deficiency.

Multiplex 330 (MX) is a portable, non-invasive fluorescence sensor that provides different multiparametric indices that are sensitive to the concentration of chlorophylls, flavonols, and anthocyanins on the leaf surface. This study investigated the use of these indices to assess the variability on free volatile composition of grapes (Vitis vinifera L.) in the field as well as other components of their quality potential in vineyards affected by iron deficiency chlorosis (IDC). Twenty non-irrigated Tempranillo/110 Richter vineyard subzones from non-affected to moderately affected by IDC were monitored in Ribera del Duero area (Spain) during two seasons. The results indicated that MX can characterize the spatial variation of leaf pigment concentrations, agronomic performance, and grape quality in vineyards affected by IDC. The MX indices measured at the leaf level close to harvest had better predictive values for the concentrations of free alcohols, volatile acids, C13-norisoprenoids, esters and acetates in the must than vine vigor, size or degree of technological maturity of the grapes. Our study demonstrates that the MX indices to estimate leaf pigment concentrations can be helpful to assess the technological maturity and free volatile composition of wine grapes in vineyards affected by IDC; nevertheless, the efficacy of the indexes may vary according to the year season.