IVAS 2022 banner
IVES 9 IVES Conference Series 9 IVAS 9 IVAS 2022 9 Infrared spectroscopy investigation of fresh grapevine organs for clustering and classification.

Infrared spectroscopy investigation of fresh grapevine organs for clustering and classification.

Abstract

The spectral information acquired from fresh whole grapevine organs have yet to be fully explored. Infrared spectroscopy provides the means to rapidly measure fresh plant material and providing extensive information on the physical and chemical structure of samples. This study aimed to explore the spectra of fresh grapevine shoots, leaves, and berries throughout the growing season for clustering and classification. Sampling was performed across two vintages (2019-2020; 2020-2021) from November to March. Five locations, seven cultivars, and 17 commercial vineyards were included. Collection of whole shoots, including leaves and grape bunches, were performed on a monthly basis. The fresh grapevine organs were analysed using three spectroscopy methods within 24-36 hours of sampling. Mid-infrared (MIR) and near-infrared (NIR), making use of a solid probe (NIR-SP) and a rotating sphere (NIR-RS), were investigated. The raw spectra were firstly investigated using principal component analysis (PCA) followed by a more novel chemometric approach, unsupervised
self-organising maps (SOM). PCA as well as unsupervised SOM showed the most considerable grouping based on organ type. Additionally, the unsupervised SOM showed separation trends based on phenological stage. Investigation of the datasets per organ with SOM showed separation based on the phenological stage for berries and shoots, as well as shoots clustering based on lignification. Supervised SOM were examined for classification based on the observed clustering per organ type, phenological stage, and lignification. The accurate prediction of organ at 90.3% was possible for the NIR-SP dataset for 2019-2021. Overlapping of various phenological stages were seen for the grape berry datasets, but prediction improved to 85.6% for the NIR-RS 2019-2021 dataset when certain phenological
stages were grouped together. Accurate predictions of lignified and unlignified shoots were also seen for the NIR-SP 2019-2021 and NIR-RS 2020-2021 datasets at 74.4% and 89.9% respectively. The possibility of using spectral variable selection to improve the supervised SOM predictions were explored and promising results obtained for certain datasets. Following variable selection with OPLS-DA and S-plots, the prediction of shoots and leaves improved by 14% for the NIR-RS 2020-2021 dataset. The prediction of lignified and unlignified shoots improved considerably to 92.3% for the NIR-SP 2019-2021 dataset and 95.9% for the NIR-RS 2020-2021 dataset. This study showed the extensive information available in infrared spectra of fresh grapevine organs and how the information could be used to achieve important clustering and classifications objectives

DOI:

Publication date: June 23, 2022

Issue: IVAS 2022

Type: Article

Authors

Van Wyngaard Elizma¹, Blancquaert Erna¹, Nieuwoudt Hélène¹and Aleixandre-Tudo Jose Luis1,²

¹South African Grape and Wine Research Institute (SAGWRI), Department of Viticulture and Oenology, Stellenbosch University, Stellenbosch, South Africa
²Instituto de Ingeniería de Alimentos para el Desarrollo (IIAD), Departamento de Tecnologia de Alimentos, Universidad Politécnica de Valencia, Valencia, Spain

Contact the author

Keywords

Spectroscopy, grapevine organs, clustering, classification

Tags

IVAS 2022 | IVES Conference Series

Citation

Related articles…

Climate, Viticulture, and Wine … my how things have changed!

The planet is warmer than at any time in our recorded past and increasing greenhouse emissions and persistence in the climate system means that continued warming is highly likely. Climate change has already altered the basic framework of growing grapes for wine production worldwide and will likely continue to do so for years to come. The wine sector can continue to play an important role in leading the agricultural sector in addressing climate change. From developing on…

Effects of graft quality on growth and grapevine-water relations

Climate change is challenging viticulture worldwide compromising its sustainability due to warmer temperatures and the increased frequency of extreme events. Grafting Vitis vinifera L.

A predictive model of spatial Eca variability in the vineyard to support the monitoring of plant status

[lwp_divi_breadcrumbs home_text="IVES" use_before_icon="on" before_icon="||divi||400" module_id="publication-ariane" _builder_version="4.19.4" _module_preset="default" module_text_align="center" module_font_size="16px" text_orientation="center"...

Towards a regional mapping of vine water status based on crowdsourcing observations

Monitoring vine water status is a major challenge for vineyard management because it influences both yield and harvest quality. It is also a challenge at the territorial scale for identifying periods of high water restriction or zones regularly impacted by water stress. This information is of major importance for defining collective strategies, anticipating harvest logistic or applying for irrigation authorisation. At this spatial scale, existing tools and methods for monitoring vine water status are few and often require strong assumptions (e.g. water balance model). This paper proposes to consider a collaborative collection of observations by winegrowers and wine industry stakeholders (crowdsourcing) as an interesting alternative. Indeed, it allows the collection of a large number of field observations while pooling the collection effort. However, the feasibility of such a project and its interest in monitoring vine water status at regional scale has never been tested.

The objective of this article is to explore the possibility of making a regional map of vine water status based on crowdsourcing observations. It is based on the study of the free mobile application ApeX-Vigne, which allows the collection of observations about vine shoot growth. This information is easy to collect and can be considered, under certain conditions, as a proxy for vine water status. This article presents the first results obtained from the nearly 18,000 observations collected by winegrowers and wine industry stakeholders during 2019, 2020 and 2021 seasons. It presents the vine shoot growth maps obtained at regional scale and their evolution over the three vintages studied. It also proposes an analysis of the factors that favoured the number of observations collected and those that favoured their quality. These results open up new perspectives for monitoring vine water status at a regional scale but above they provide references for other crowdsourcing projects in viticulture.

Impact of geographical location on the phenolic profile of minority varieties grown in Spain. II: red grapevines

Because terroir and cultivar are drivers of wine quality, is essential to investigate theirs effects on polyphenolic profile before promoting the implantation of a red minority variety in a specific area. This work, included in MINORVIN project, focuses in the polyphenolic profile of 7 red grapevines minority varieties of Vitis vinifera L. (Morate, Sanguina, Santafe, Terriza Tinta Jeromo Tortozona Tinta) and Tempranillo) from six typical viticulture Spanish areas: Aragón (A1), Cataluña (A2), Castilla la Mancha (A3), Castilla –León (A4), Madrid (A5) and Navarra (A6) of 2020 season. Polyphenolic substances were extracted from grapes. 35 compounds were identified and quantified (mg subtance/kg fresh berry) by HPLC and grouped in anthocyanins (ANT) flavanols (FLAVA), flavonols (FLAVO), hydroxycinnamic (AH), benzoic (BA) acids and stilbenes (ST). Antioxidant activity (AA, mmol TE /g fresh berry) was determined by DPPH method. The results were submitted to a two-way ANOVA to investigate the influence of variety, area and their interaction for each polyphenolic family and cluster analysis was used to construct hierarchical dendrograms, searching the natural groupings among the samples. Sanguina (A3) had the most of total polyphenols while Tempranillo (A5) those of ANT. Sanguina (A2) and (A3) reached the highest values of FLAVO, FLAVA and AA. These two last samples had also the maximum of AA. The effect cultivar and area were significant for all polyphenolic families analyzed. A high variability due to variety (>50%) was observed in FLAVA and the maximum value of variability due to growing area was detected in AA (86.41%), ANT and FLAVO (51%); the interaction variety*zone was significant only for ANT, FLAVO, EST and AA. Finally, dendrograms presented five cluster: i) Sanguina (A2); ii) Sanguina (A3); iii) Tempranillo (A5); iv) Tempranillo (A3); Terriza (A3,A5), Morate (A5,A6); v) Santafé (A1,A6); Tortozona tinta (A1,A3,A6); Tinta Jeromo (A3,A4).