terclim by ICS banner
IVES 9 IVES Conference Series 9 High-resolution aerial thermography for water stress estimation in grapevines

High-resolution aerial thermography for water stress estimation in grapevines

Abstract

Aerial thermography has emerged as a promising tool for water stress detection in grapevines, but there are still challenges associated with this technology, particularly concerning the methodology employed to extract reliable canopy temperature values. This consideration is relevant especially in vertically trained vineyards, due to the presence of multiple surfaces which are captured by drone thermal cameras with high-resolution. To test the technology and the data analysis required, a field study was conducted during the 2022-2023 season in a model vineyard with multiple scions-rootstock combinations trained on a vertical shoot-positioning (VSP) system. Additionally, three irrigation regimes were implemented to introduce variability in water stress levels. A commercial Unmanned aerial vehicle (UAV) equipped with an integrated RGB, and thermal camera was used to capture high-resolution aerial images over the vineyard. Eight different pixel extraction methods, considering classical and novel approaches, were tested against manual pixel extraction to determine which method performed the best. From the methods tested, the two Gaussian mixture models (GMM2) showed the best performance in terms of accuracy and precision. The average canopy temperature obtained by this method was contrasted with stem water potential measurements, showing significant differences between well-watered and dryland treatments. Aerial thermography complemented by the GMM2 method shows great potential as a tool for water stress estimation in grapevines, however, several factors play a role in method performance. These include the degree of stress in the vineyard, amount of cover crops, and canopy density amongst others. Suggestions regarding the critical aspects that need to be evaluated further to optimize the methodology and reduce the uncertainties associated to the application of this technology will be discussed in context of the results obtained.

DOI:

Publication date: June 14, 2024

Issue: Open GPB 2024

Type: Article

Authors

Carlos Poblete-Echeverria1*, Thomas Chalmers1, Melane A. Vivier1

1 South African Grape and Wine Research Institute (SAGWRI), Faculty of AgriSciences, Stellenbosch University, Matieland 7602, South Africa

Contact the author*

Keywords

Precision viticulture, Water management, Digital analysis, Pixel extraction methods, Thermal imagery

Tags

IVES Conference Series | Open GPB | Open GPB 2024

Citation

Related articles…

METAPIWI: unveiling the role of microbial communities in PIWI grapes for sustainable winemaking

The METAPIWI project advances viticulture research by examining microbial communities in PIWI (fungus-resistant) grapevines compared to traditional Vitis vinifera. It investigates how these microbes influence spontaneous fermentation and the production of distinct metabolites and aromas.

Impact of reduction alcohol techiniques in the aromatic chemical profile of rosé Tempranillo wines

Studying the impact of reducing alcohol techniques in the chemical composition of the aromatic profile of rosé Tempranillo wines from the spanish region of Castilla-La Mancha INTRODUCTION: In the last decades there has been an increseasing demand of wines with low or non-existing alcohol concentration due to the negative effects that alcohol has in health. In spite of that, there are not laws that protect these products, and there is also a great difficulty in the elaboration of these type of wines due to the increasing temperatures because of climate change. This is why the oenological industry has made great advances in the development of different techniques that could satisfy consumers’ demands without modifying wine quality. The most used techniques have been post-fermentative ones.

The evaluation of tannin activity in south african red wines

Astringency is an important red wine quality attribute, which can be measured both chemically and sensorially. The use of tannin activity shows potential as a valuable chemical measurement in understanding red wine mouthfeel properties such as astringency and bitterness, which is also affected by tannin structural factors, in addition to matrix effects. Tannin activity is defined as the enthalpy of interaction between tannins and a hydrophobic surface. Studies involving tannin activity have been performed since the early 2010’s, but chemosensory studies used to evaluate how structure-activity relationships change across multiple, consecutive vintages are limited. The aim of this study is to investigate how tannin activity may be linked to red wine mouthfeel, and how all these variables may change according to wine age.

Cross analytical and sensory differentiation of monovarietal white wines from four autochthonous grape varieties: focus on macromolecules

White wines contain macromolecules such as proteins, phenolic compounds and polysaccharides. On a sensory
level, these compounds contribute to the ‘mouthfeel’ that differentiates the white wines worldwide [1].

A geologic numeric mapping, with geophysic transects, of Marsannay’s vineyard (Burgundy, France)

Marsannay est l’appellation la plus septentrionale de la Côte de Nuits, à la limite Sud de Dijon. Elle regroupe trois villages, Chenôve, Marsannay-la-Côte et Couchey, et constitue l’appellation la plus vaste de la Côte de Nuits avec 315 hectares en A.O.C. Elle possède uniquement des niveaux d’appellations régionales et communales depuis 1987.