Abstract
ABSTRACT: Although water deficit and iron deficiency chlorosis are common environmental stresses in the Mediterranean area, few data are reported in the literature on their effects on vineyards, when acting simultaneously. The main objective of this research was to study the combined effects of iron deficiency and water status on vigor, yield and fruit composition in rainfed vineyards. Moreover, the investigation aimed to evaluate the feasibility of using foliar chlorophyll content (Chl) and predawn leaf water potential (LWP), measured at veraison, to assess potential quality of grapes in the framework of precision viticulture. For this, 24 non-irrigated ‘Tempranillo’ vineyard subzones were monitored in Ribera del Duero (North-Central Spain) during three consecutive seasons (2011-2013). The analysis of variance and principal component analysis showed that malic acid concentrations of the must were impacted only by Chl, whereas total soluble solids and total acidity were mainly modified by LWP. Both water and iron status reduced yield and berry weight and had additive effects on extractable anthocyanin content in grapes, total polyphenol index and color density of the must. In all seasons, the ratio Chl/LWP had a better predicting value for quality parameters of these grapes than leaf area index, Chl or LWP individually. The present work demonstrates the potential interest of physiological indexes combining water status and foliar chlorosis as indicators of grape phenolic potential in rainfed vineyards affected by iron deficiency.
Highlights
Water deficit and iron nutritional deficiency are two frequent types of environmental stresses that cause serious economic losses in grapevine production in the Mediterranean area
ABSTRACT: water deficit and iron deficiency chlorosis are common environmental stresses in the Mediterranean area, few data are reported in the literature on their effects on vineyards, when acting simultaneously
The analysis of variance and principal component analysis showed that malic acid concentrations of the must were impacted only by Chl, whereas total soluble solids and total acidity were mainly modified by leaf water potential (LWP)
Summary
Water deficit and iron nutritional deficiency (iron chlorosis) are two frequent types of environmental stresses that cause serious economic losses in grapevine production in the Mediterranean area. While iron deficiency leads to a decrease in the synthesis of photosynthetic pigments (Val et al, 1987) and a lower efficiency of photosystem II (Bavaresco et al, 2006; Hailemichael et al, 2016), water deficit causes marked stomatal closure, reducing availability of CO2 in leaf mesophyll (Flexas et al, 2002). The loss of photosynthetic capacity depresses yield and vigor both in iron (Echeverría et al, 2017; Tagliavini and Rombolà, 2001; Martín et al, 2007) and water (Balint and Reynods, 2014; Van Leeuwen et al, 2009) affected grapevines, and reduces synthesis and accumulation of substances in the fruit during ripening (Pirie and Mullins, 1980; Ojeda et al, 2002). Moderate stress levels can have positive effects on grape quality, as the plants restrict vegetative growth, they have less yield and smaller berries (Roby and Matthews, 2004; Balint and Reynolds, 2017), and concentrate constituents, such as phenolic compounds, which are responsible for color, astringency and bitterness of red wines (Zoecklein et al, 1990)
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