Biology subjects

Dokoozlian, N.

Publications and source records attributed to Dokoozlian, N..

4 recordsLinked to original sources

bioRxiv2026

Supplemental irrigation during heat waves affects yield but not whole-vine carbohydrates in wine grapes

As extreme heat events increase in frequency and intensity worldwide, understanding how woody perennial crops respond to higher maximum temperatures is critical. Perennials face distinct challenges, persisting across many seasons under increasingly variable and extreme conditions, and heat waves threaten the viability of wine grape cultivars through impacts on yield, wine quality, and long-term vine health. To test whether irrigation practices before and during heat waves affect grapevine carbon (C) storage and health, we experimentally manipulated irrigation regimes surrounding heat waves from 2019-2021 in a commercial Cabernet Sauvignon vineyard in the Lodi AVA of Californias Central Valley. Vine physiological traits and yield were measured throughout, and whole-vine nonstructural carbohydrate (NSC) concentrations were quantified after three growing seasons. Although lower supplemental irrigation reduced photosynthesis, stomatal conductance, and fruit yield, whole-vine NSCs did not differ significantly in any perennial organ by the experiments end, indicating that reproductive output and final NSC status responded to irrigation on different timescales. These results suggest that moderate supplemental irrigation during heat events is sufficient to mitigate negative impacts on yield and quality while supporting recovery of NSC reserves, though longer-term monitoring is needed to confirm that this short-term resilience persists.

Plant Biology↗

bioRxiv2026

Enhanced Irrigation during Extreme Heat Events Preserves Anthocyanins in Cabernet Sauvignon

Globally, heat waves (HWs) have become more frequent, intense, and prolonged, with extreme temperatures that reduce quality or result in crop loss in wine grapes. Irrigation prior to or during HWs is one of the most common means of mitigating damage to vines and berries. However, the effect of this practice on flavonoids is not well established. Red wine quality is directly impacted by phenolics, including anthocyanins and proanthocyanidins (PAs). This study was conducted over three vintages (2019-2021) in a commercial vineyard to evaluate the impact of supplemental irrigation - applied before and during HWs - on winegrape chemistry in Cabernet Sauvignon. Results demonstrated that supplemental irrigation significantly reduced anthocyanin loss compared to a control treatment maintained at 60% evapotranspiration (ET), and that pre-HW irrigation can mitigate some of the deleterious effects on classes of flavonoids important to red wine quality. Furthermore, applying excessive water (3x, or 180% ET) had no additional beneficial effects on flavonoids relative to a moderate supplemental application (2x, or 120% ET).

biochemistry↗

bioRxiv2026

Optimizing irrigation during heat events sustains grapevine physiology and fruit production

O_LIIncreasing frequency, intensity, and duration of heat waves (HWs) threaten agricultural production globally by constraining physiological function and fruit production. Supplemental irrigation mitigates heat stress in grapevine and other woody perennial crops, yet water scarcity necessitates optimized irrigation strategies during extreme heat. C_LIO_LIWe conducted a three-year field trial in a commercial Cabernet Sauvignon vineyard, applying differential irrigation only before and during naturally occurring HWs: baseline (50% ET), moderate (90-120% ET), and high (120-180% ET). We monitored water potentials, leaf gas exchange, canopy temperature, yield, and berry composition. C_LIO_LIBaseline irrigation consistently reduced net photosynthesis, stomatal conductance, and leaf cooling capacity during HWs. Moderate supplemental irrigation maintained gas exchange, transpiration, and leaf temperature, mitigating yield losses. Excessive irrigation beyond moderate levels provided no additional physiological benefit and decreased crop water use efficiency and berry quality. C_LIO_LIOur results demonstrate that targeted, event-based irrigation sustains grapevine physiological performance and fruit production under extreme heat, whereas both insufficient and excessive water negatively affect carbon assimilation, stomatal regulation, and crop productivity. These findings emphasize the importance of aligning water management with heat event timing to preserve vine function, optimize water use, and maintain yield and fruit quality in water-limited regions. C_LI

plant biology↗

bioRxiv2022

Scalable early detection of grapevine virus infection with airborne imaging spectroscopy

Viral diseases, including Grapevine Leafroll-associated Virus Complex 3 (GLRaV-3), cause $3 billion in damages and losses to the United States wine and grape industry annually. GLRaV-3 has a well-studied, year-long latent period in which vines are infectious but do not yet display visible symptoms, making it an ideal model pathosystem to evaluate the scalability of symptomatic and asymptomatic imaging spectroscopy-based disease detection. Plant disease causes physiological and chemical changes to occur locally and systemically throughout a plant, which imaging spectroscopy can detect both directly and indirectly. Reliable and scalable disease detection during the latent period would greatly reduce management costs, as current detection methods are entirely ground-based, labor-intensive, and expensive. Here, we use data collected in September 2020 by the NASA Airborne Visible/Infrared Imaging Spectrometer Next Generation (AVIRIS-NG) to detect GLRaV-3 in Cabernet Sauvignon grapevines in Lodi, CA. During September 2020 and 2021, industry collaborators scouted 317 acres of Vitis vinifera winegrapes for visible disease symptoms, and collected a subset for confirmation molecular testing at a commercial facility. Grapevines identified as visibly diseased in 2021 were assumed to have been latently infected (asymptomatic) during the September 2020 AVIRIS-NG data collection. We combined random forest with synthetic minority oversampling technique (SMOTE) to train multiple spectral models able to distinguish between non-infected (NI) and GLRaV-3-infected grapevines. We observed clear spectral differences that allowed for differentiation between NI and GLRaV-3 infected vines both pre- and post-symptomatically at 1m through 5m resolution. Our two best performing models had 87% accuracy (0.73 Kappa) distinguishing between NI and asymptomatic (aSy), and 85% accuracy (0.71 Kappa) distinguishing between NI and (aSy + symptomatic [Sy]) respectively. We hypothesize these spectral differences are linked to changes in overall plant physiology induced by disease, as visible foliar symptoms were restricted to the lower canopy. HighlightsO_LIAirborne imaging spectroscopy allows for scalable early-detection models of grapevine leafroll-associated virus complex 3 (GLRaV-3). C_LIO_LIRandom Forest based models trained with scouting ground data and imaging spectroscopy are accurate up to 5 meter but perform best at 3 meter spatial resolution. C_LIO_LIGLRaV-3 detection via imaging spectroscopy will not replace existing field scouting strategies or molecular testing but supplement by allowing for more strategic resource deployment to improve the overall financial, environmental, and societal sustainability of winegrape production. C_LI

pathology↗