Advertisement
Research Report

Severe Preveraison and Moderate Postveraison Deficit Irrigation Improves Berry Phenolics in Warm-Climate Pinot noir

Suraj Kar, Cody R. Copp, Joseph B. DeShields, Ricky W. Clark, Alexander D. Levin
Am J Enol Vitic.  2025  76: 0760024  ; DOI: 10.5344/ajev.2025.25016

Article Figures & Data

Figures

  • Figure 1
    Figure 1

    Applied water amounts in each irrigation treatment in both years of the study as a function of phenology. WC, well-watered control; ED, early deficit; LD, late deficit; DC, dry control.

  • Figure 2
    Figure 2

    Response of stem water potential (Ψstem) to irrigation rate (% vine evapotranspiration [ETc]) pre- and postveraison in 2017 (circles/solid lines) and 2018 (triangles/dashed lines). Data points are irrigation treatment means ± 1 standard error (SE; n = 3). Within each year, data were pooled in each phenological period to include five to six measurement dates. Preveraison treatments were imposed from when the Ψstem threshold of −0.8 MPa was reached (averaged across all plots) until veraison, and postveraison treatments were imposed from veraison until harvest. All plots were irrigated at 100% ETc postharvest until the end of October. Breakdown of each pre- and postveraison treatment is detailed in Table 1. WC, well-watered control; ED, early deficit; LD, late deficit; DC, dry control.

  • Figure 3
    Figure 3

    Responses of berry phenolic concentration (mg/g) and content (mg/berry) to irrigation rate (% vine evapotranspiration [ETc]) pre- and postveraison. Data points are irrigation treatment means (excluding dry control [DC]) ± 1 standard error (SE; n = 3) taken from Table 5. IRPs, iron-reactive phenolics.

  • Figure 4
    Figure 4

    Relative increase of berry phenolic compound concentration (mg/g) and content (mg/berry) in response to irrigation rate (% vine evapotranspiration [ETc]) pre- or postveraison. Percent increase data were calculated relative to well-watered control (WC) using means from Table 5 (excluding dry control [DC]). Separate linear and polynomial regressions were fit to pre- and postveraison data sets, respectively. IRPs, iron-reactive phenolics.

Tables

  • Table 1

    Description of irrigation treatments based on irrigation rate. Preveraison treatments were imposed from when the stem water potential (Ψstem) threshold of −0.8 MPa was reached (averaged across all plots) until veraison, and postveraison treatments were imposed from veraison until harvest. All plots were irrigated at 100% vine evapotranspiration (ETc) postharvest until the end of October. WC, well-watered control; ED, early deficit; LD, late deficit; DC, dry control.

    Table 1
  • Table 2

    Monthly totals for growing degree days (GDD), reference evapotranspiration (ETo), estimated vine evapotranspiration (ETc), and precipitation.

    Table 2
  • Table 3

    Response of yield components to irrigation treatments at harvest. Means ± 1 standard error (SE; n = 3) were calculated for main effects only. Trend analyses for preveraison deficit (ED) and postveraison deficit (LD) were conducted on treatments arranged according to water application and excluding dry control (DC) (i.e., ED: WC-ED75-ED50-ED25 and LD: WC-LD75-LD50-LD25), where WC is well-watered control: vines were irrigated at 100% vine evapotranspiration (ETc) during both pre- and postveraison; the number within each treatment notation (75, 50, and 25) indicates the irrigation rate in % ETc that the vines received either pre- (ED) or post- (LD) veraison. The vines were irrigated at 100% ETc for the rest of the season. Breakdown of each pre- and postveraison treatment is detailed in Table 1. ANOVA, analysis of variance.

    Table 3
  • Table 4

    Response of berry chemistry to irrigation treatments at harvest. Means ± 1 standard error (SE; n = 3) were calculated for main effects only. Trend analyses for preveraison deficit (ED) and postveraison deficit (LD) trends were conducted on treatments arranged according to water application and excluding dry control (DC) (i.e., ED: WC-ED75-ED50-ED25 and LD: WC-LD75-LD50-LD25), where WC is well-watered control: vines were irrigated at 100% vine evapotranspiration (ETc) during both pre- and postveraison; the number within each treatment notation (75, 50, and 25) indicates the irrigation rate in % ETc that the vines received either pre- (ED) or post- (LD) veraison. The vines were irrigated at 100% ETc for the rest of the season. Breakdown of each pre- and postveraison treatment is detailed in Table 1. TSS, total soluble solids; TA, titratable acidity; ANOVA, analysis of variance.

    Table 4
  • Table 5

    Response of skin phenolic composition to irrigation treatments at harvest. Each compound was evaluated on a concentration (mg/g) and content (mg/berry) basis. Anthocyanins are in malvidin-3-glucoside equivalents. Tannins and iron-reactive phenolics (IRPs) are in catechin equivalents. Means ± 1 standard error (SE; n = 3) were calculated for main effects only. Trend analyses for preveraison deficit (ED) and postveraison deficit (LD) trends were conducted on treatments arranged according to water application and excluding dry control (DC) (i.e., ED: WC-ED75-ED50-ED25 and LD: WC-LD75-LD50-LD25), where WC is well-watered control: vines were irrigated at 100% vine evapotranspiration (ETc) during both pre- and postveraison; the number within each treatment notation (75, 50, and 25) indicates the irrigation rate in % ETc that the vines received either pre- (ED) or post- (LD) veraison. The vines were irrigated at 100% ETc for the rest of the season. Breakdown of each pre- and postveraison treatment is detailed in Table 1. ANOVA, analysis of variance.

    Table 5

Additional Files

  • Supplemental Table 1   Mean stem water potential (Ψstem) response to irrigation treatments during two phenological periods: from treatment imposition to veraison (preveraison), and from veraison to harvest (postveraison). Treatment means (and standard error [SE]) are calculated from pooled data encompassing five to six measurements for each period (n = 3 to 5). P values adjacent to means represent comparisons against WC treatment and are adjusted for multiplicity using Dunnett’s method. Trend analyses for preveraison deficit (ED) and postveraison deficit (LD) trends were conducted on treatments arranged according to water application and excluding dry control (DC) (i.e., ED: WC-ED75-ED50-ED25 and LD: WC-LD75-LD50-LD25), where WC is well-watered control: vines were irrigated at 100% vine evapotranspiration (ETc) during both pre- and postveraison; the number within each treatment notation (75, 50, and 25) indicates the irrigation rate in % ETc that the vines received either pre- (ED) or post- (LD) veraison. The vines were irrigated at 100% ETc for the rest of the season. Breakdown of each pre- and postveraison treatment is detailed in Table 1. 

    Supplemental Figure 1       Soil properties of the vineyard site. Data was obtained from the USDA-NRCS Web Soil Survey (https://websoilsurvey.sc.egov.usda.gov). Experimental blocks (B1 to B5) are marked with a red border. Block 1 (B1) was expanded to the right to show the assignment of irrigation treatments. Rectangles in the middle of each treatment plot indicate eight data vines. WC, well-watered control; DC, dry control; LD, late deficit; ED, early deficit. AWS, available water supply.
Back to top
Print
View full PDF
Email Article
Citation Tools

Open Access
Severe Preveraison and Moderate Postveraison Deficit Irrigation Improves Berry Phenolics in Warm-Climate Pinot noir
Suraj Kar, Cody R. Copp, Joseph B. DeShields, Ricky W. Clark, Alexander D. Levin
Am J Enol Vitic.  2025  76: 0760024  ; DOI: 10.5344/ajev.2025.25016
del.icio.us logo Twitter logo Facebook logo Mendeley logo
Save to my folders

Jump to section