Response of Riesling Grapes and Wine to Temporally and Spatially Heterogeneous Soil Water Availability

Supplemental Table 1  List of chemical standards used to quantify the phenolic profile of Riesling wines made from fruit harvested in a vineyard in southeastern Washington. Each compound is accompanied by the chemical class, the commercial supplier, and the solvent used to prepare the high-performance liquid chromatography standards for calibration curves.

Supplemental Table 2  List of analytical standards used to semi-quantify the volatile composition of Riesling wines made from fruit harvested in a vineyard in southeastern Washington. Each compound is accompanied by commercial supplier and grouped by chemical class. For gas chromatography-mass spectrometry analysis, all analytical standards were prepared using methanol as solvent.

Supplemental Table 3  Effect of irrigation treatment (a no-stress control [FULL], regulated deficit irrigation [RDI], and partial rootzone drying [PRD]) and growing season on irrigation water use efficiency, irrigation water footprint, and total water footprint of a Riesling vineyard in southeastern Washington over three years.

Supplemental Table 4  Phenolic compounds (µg/L) measured by high-performance liquid chromatography in Riesling wines obtained from three irrigation treatments (a no-stress control [FULL], regulated deficit irrigation [RDI], and partial rootzone drying [PRD]) in a vineyard in southeastern Washington. Data are means of two technical replicates for each of three wine replicates in two years.

Supplemental Table 5  Volatile organic compounds (in internal standard response ratio) measured by gas chromatography-mass spectrometry in Riesling wines obtained from three irrigation treatments (a no-stress control [FULL], regulated deficit irrigation [RDI], and partial rootzone drying [PRD]) in a vineyard in southeastern Washington in 2019. Data are means of two technical replicates for each of three wine replicates and include only compounds that were above the detection limit.

Supplemental Table 6  Volatile organic compounds (in internal standard response ratio) measured by gas chromatography-mass spectrometry in Riesling wines obtained from three irrigation treatments (a no-stress control [FULL], regulated deficit irrigation [RDI], and partial rootzone drying [PRD]) in a vineyard in southeastern Washington in 2021. Data are means of two technical replicates for each of three wine replicates and include only compounds that were above the detection limit.

Supplemental Figure 1  Diurnal changes of leaf water potential (Ψ_leaf) measured in an irrigation trial conducted in a Riesling vineyard in southeastern Washington over three years. Treatments included a no-stress control (FULL), regulated deficit irrigation (RDI), and partial rootzone drying (PRD). Data show Ψ_leaf during pretreatment drydown before (day of year [DOY] 198, T_max = 27.2°C) and during (DOY 204, T_max = 34.3°C) a heatwave in 2019 (A), Ψ_leaf for each treatment on preveraison DOY 218 in 2020 (B), and Ψ_leaf for two treatments and two additional treatments (irrigation to field capacity or no irrigation since budbreak) on postveraison DOY 239 in 2021 (C). Data show means ± SE (n = 6 in A and B; n = 4 in C); time is Pacific Daylight Saving Time.

Supplemental Figure 2  Irrigation water supply estimated from drip emitter number and flow rate against flow meter readings during two independent irrigation cycles in 2020 and 2021 in an irrigation trial conducted in a Riesling vineyard in southeastern Washington. Flow meters were installed in submains supplying water to the four replicates of each treatment.

Supplemental Figure 3  Seasonal growing degree day (GDD; base 10°C) accumulation from April through October near the Washington State University Roza vineyard in southeastern Washington. Data were obtained from the AgWeatherNet Roza.2 station (https://weather.wsu.edu) located ~550 m from the trial site.

Supplemental Figure 4  Seasonal changes in the volumetric soil water content (θ_v) in the top 60 to 90 cm of the soil profile and midday leaf water potential (Ψ_leaf) measured in an irrigation trial conducted in a Riesling vineyard in southeastern Washington over three years. Treatments included a no-stress control (FULL), regulated deficit irrigation (RDI), and partial rootzone drying (PRD). For PRD, θ_v is plotted separately for the wet (PRD_wet) and dry (PRD_dry) sections. Data show means ± SE (n = 4) for 2019 (A, B), 2020 (C, D), and 2021 (E, F). Vertical dashed lines indicate phenological stages fruit set (FS), veraison (V), and harvest (H).

Supplemental Figure 5  Association between relative extractable soil water content (θ_e) of the top 60 to 90 cm of the soil profile and midday leaf water potential (Ψ_leaf), measured from fruit set through harvest in an irrigation trial conducted in a Riesling vineyard in southeastern Washington over three years (2019 to 2021). Non-linear regression and curve fitting was applied to each of three irrigation treatments: a no-stress control (FULL; r = 0.55); regulated deficit irrigation (RDI; r = 0.69); and partial rootzone drying (PRD; r = 0.53). The θ_e for PRD is the average for the wet and dry sections.

Supplemental Figure 6  Association between cluster sun exposure relative to ambient light at veraison and pruning weight (A) or number of shoots per vine (B) in an irrigation trial conducted in a Riesling vineyard in southeastern Washington over three years (2019 to 2021). Treatments included a no-stress control (FULL), regulated deficit irrigation (RDI), and partial rootzone drying (PRD).

Supplemental Figure 7  Association between average cluster weight and average midday leaf water potential (Ψ_leaf), measured from fruit set through veraison in an irrigation trial conducted in a Riesling vineyard in southeastern Washington over three years (2019 to 2021). Treatments included a no-stress control (FULL), regulated deficit irrigation (RDI), and partial rootzone drying (PRD).

Supplemental Figure 8  Effect of three irrigation treatments (a no-stress control [FULL], regulated deficit irrigation [RDI], and partial rootzone drying [PRD]) on yield-to-pruning weight ratio in an irrigation trial conducted in a Riesling vineyard in southeastern Washington over three years. Bars show means ± SE (n = 4).

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