Combined effects of water status and iron deficiency chlorosis on grape composition in non-irrigated vineyards

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)(2012)(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.

Aroma composition of Tempranillo grapes as affected by iron deficiency chlorosis and vine water status

“…According to previous studies carried out in the same area (Hailemichael et al, 2016;González et al, 2019), no consistent correlations were obtained between Chl and LWP in 2016 (r = 0.04, p > 0.05) and 2017 (r = 0.12, p > 0.05); therefore, both variables could be considered independent.…”

“…Increases in TPC were associated to the incidence of iron deficiency, according to Bavaresco et al (2005) and González et al (2019). However, due to LWP × Chl interaction (Table 3), differences between low and high Chl values were detected (p < 0.05) only in subzones with better water status at veraison (1529 mg kg -1 versus 1180 mg kg -1 in 2016, 940 mg kg -1 versus 780 mg kg -1 in 2017).…”

“…In different ways, water stress (Flexas et al, 2002) and iron chlorosis (Val et al, 1987;Bavaresco et al, 2006;Hailemichael et al, 2016) decline photosynthetic activity in grapevines, which depresses the synthesis and accumulation of substances in the fruits (Pirie and Mullins, 1980;Ojeda et al, 2002). Nevertheless, mild to moderate stress levels could have positive effects on grape quality, as the plants restrict vegetative growth, have less yield and smaller berries, concentrating constituents such as sugars and phenolic compounds (Balint and Reynolds, 2017;González et al, 2019).…”

Relationships between chlorophyll content of vine leaves, predawn leaf water potential at veraison, and chemical and sensory attributes of wine

“…Each season, data on foliar chlorophyll (Chl) content, predawn leaf water potential (LWP), and leaf area index (LAI) were obtained in the study subzones at veraison stage, with 75% of coloured berries (23-24 August 2016 and 9-10 August 2017). Chl content per leaf area unit (μg cm −2 ) was obtained following González et al 12 from readings of a CL-01 portable colorimeter (Hansatech Instruments Ltd, King's Lynn, UK). Data were recorded from 30 leaves in each subzone, always choosing the fourth or fifth fully expanded leaf counting from the tip.…”

“…10,11 Recent studies in Ribera del Duero Designation of Origin (Spain) have demonstrated that mild to moderate iron deficiency can improve the phenolic content and aromatic potential of Tempranillo grapes. 12,13 It would be interesting to study to what extent these improvements are transferred to the composition and sensory characteristics of the wine. To the best of our knowledge, there are currently no studies on how iron deficiency affects the chemical and sensory qualities of wine.…”