GiESCO 2019 banner
IVES 9 IVES Conference Series 9 GiESCO 9 Statewide relationships between water potentials, gas exchange and δ13c of grape musts in California. Implications for use in precision viticulture

Statewide relationships between water potentials, gas exchange and δ13c of grape musts in California. Implications for use in precision viticulture

Abstract

Context and purpose of the study– The measurement of carbon isotopic discrimination of musts (δ13C) at harvest is an integrated assessment of water status during ripening of grapevine. It is an alternative to traditional measurements of water status in the field, which is crucial for understanding spatial variability of plant physiology at the vineyard scale, proven useful for delineation of management zones in precision viticulture. The aim of this work was to attune the method for the first time to California conditions across a range of areas and cultivars with different hydric behavior, and to evaluate its efficiency in delineating management zones for selective harvest in commercial vineyards.
Material and methods – The experiment was performed in 91 experimental units located at four different locations across the State, planted to three different table and wine grape cultivars (Crimson Seedless, Cabernet Sauvignon, Merlot) whose hydric behavior ranged from isohydric to anisohydric, and in between. Leaf gas-exchanges and stem water potentials (Ψ) were measured routinely in each experimental unit, and the δ13C at harvest. At one of the locations, δ13C and water potentials were measured on an equi-distant grid, spatialized and clustered to compare their efficiency in the differentiated the vineyard block into two distinct zones having grapes with different flavonoid composition.
Results – A significant and direct relationship was evident between δ13C and average stem water potential (R2 = 0.72), stomatal conductance (R2 = 0.66) and net carbon assimilation (R2 = 0.62) measured throughout the season. Differences between the cultivars were small, independently from their reported hydric behavior and it was possible to pool all of them together. This was also true in crossed relationships between stem water potential, stomatal conductance, and net carbon assimilation that were not able to clearly discriminate between the reported hydric behaviors. A unique state-wide calibration was therefore developed between δ13C and plant water status. Simulation exercise demonstrated that variability in slope and R2 of the δ13C ~ Ψ regression can be caused by comparison of discrete measurements (Ψ) of water status to a continuous measurement (δ13C), and that apparent variability decreased with increasing sampling points of the discrete measurement (Ψ).The use of δ13C was then tested in a precision viticulture context. The management zones obtained by δ13C and stem water potentials were similar at 72% and allowed to separate the harvest in two pools, having statistically different grape composition (soluble solids, organic acids and anthocyanin profiles). Our results provided evidence that δ13C discrimination was a reliable and repeatable assessor of plant water status in vineyard ecosystems useful for delineation of management zones in precision viticulture.

DOI:

Publication date: September 18, 2023

Issue: GIESCO 2019

Type: Poster

Authors

Luca BRILLANTE1*, Runze YU2, Johann MARTINEZ-LUSCHER2, S. Kaan KURTURAL2

1 Dep. of Viticulture and Enology, California State University, Fresno, CA 93740. USA

2 Department of Viticulture and Enology, University of California, Davis, CA 95616, USA

Keywords

grapevine, δ13C, carbon stable isotopes, water status, leaf gas-exchange, precision agriculture, selective harvest

Tags

GiESCO | GiESCO 2019 | IVES Conference Series

Citation

Related articles…

Berry maturity effects on physic and chemical characteristics of traditional sparkling wines produced from Chardonnay and Sauvignon blanc grapes.

One of the consequences of global warming is the quick berry development giving rise to a disconnection between sugar accumulation and the formation of important quality minor compounds such as phenolics and volatile compounds being a huge challenge for the oenologist [1]. Thus, this phenomenon is forcing the search on strategies for maintaining the quality of wines despite this situation. One possibility is to make an early harvest with a low sugar concentration (18ºbrix) and advanced harvest for sparkling wine (20-21ºbrix) and afterwards to combine base wines properly and carry out the second fermentation trying to compensate the lack of secondary metabolites due to the quick berry development and higher alcohol degree of the second one, not adequate itself for sparkling wine. The aim of this study was to assess the chemical and physical characteristics, mainly volatile profile, and foaming properties of sparkling wines from grapes of Chardonnay and Sauvignon blanc.

Spatial variability of grape berry maturation program at the molecular level 

The application of sensors in viticulture is a fast and efficient method to monitor grapevine vegetative, yield and quality parameters and determine their spatial intra-vineyard variability. Molecular analysis at the gene expression level can further contribute to the understanding of the observed variability by elucidating how pathways responsible for different grape quality traits behave in zones diverging for one or the other parameter. The intra-vineyard variability of a Cabernet Sauvignon vineyard was evaluated by a standard Normalized Difference Vegetation Index (NDVI) mapping approach, employing UAV platform, accompanied by detailed ground-truthing (e.g. vegetative, yield, and berry ripening compositional parameters) that was applied in 14 spots in the vineyard. Berries from different spots were additionally investigated by microarray gene expression analysis, performed at five time points from fruit set to full ripening.

Combination of NIR multispectral information acquired from a ground moving vehicle with AI methods to assess the vine water status in a Tempranillo (Vitis vinifera L.) commercial vineyard

Increasing water scarcity and unpredictable rainfall patterns necessitate efficient water management in grape production. This study proposes a novel approach for monitoring grapevine water status in a commercial vertically-shoot-positioned Vitis vinifera L. Tempranillo vineyard using non-invasive spectroscopy with a battery of different AI methods to assess vineyard water status, that could drive precise irrigation. A contactless, miniature NIR spectrometer (900-1900 nm) mounted on a moving vehicle (3 Km/h) was employed to collect spectral data from the vines’ northeast side along six dates in season 2021.

Exploring the gene regulatory networks of WRKY family in grapevine (Vitis vinifera  L.) using DAP-Seq

The recent development of regulatory genomics has raised increasing interest in plant research since transcriptional regulation of genes plays a pivotal role in many biological processes. By shedding light on the target genes of the various transcription factors (TFs), it is therefore possible to infer the influence they exert on the different molecular mechanisms. In this regard, the attention was focused on WRKYs, a family of TFs almost exclusively found in plant species. In grapevine, WRKYs are involved in several biological processes, playing a key role in berry development, hormonal balance and signalling, biotic and abiotic stresses responses, and secondary metabolites biosynthesis.

Management of varietal thiols in white and rosé wines using biotechnical tools

The present study evaluates the effect of prefermentative maceration enzymes and yeast autolysate on the concentration of conjugated precursors and volatile thiols, respectively.Sauvignon blanc and Merlot grapes underwent skin-contact maceration with or without pectolytic enzymes, for the production of white and rosé wines