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.

Download the abstract

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…

Chemical systems behind wine aroma perception: overview, genesis and evolution

This talk presents a revision of our knowledge and understanding of the role played by the different aroma chemicals in the positive aroma attributes of wine. A systematic approach to classifying the different aroma chemicals of wine is presented .

Read More

Impact of soil-applied and foliar-applied nitrogen on grape and wine composition

Foliar application of urea may be an efficient way to alter grape and wine composition without increasing vine vigor. However, we know little about the impact of this practice on phenolic compounds and yeast assimilable nitrogen (YAN). Adequate YAN is required for an efficient and complete fermentation, while phenolics are particularly important for the sensory profile of red wines. The goal of this study is to test the impact of foliar urea application at veraison, compared to the traditional soil-applied nitrogen fertilization early in the season, on Syrah berry and wine composition in field conditions.

Read More

Implications of the respect of pruning principles on grapevine development

After some decades sunk into oblivion, pruning has recently recovered the focus of grape growers and viticulturists worldwide. Attention is now being paid to the respect the sap flow continuity and to pruning wounds, as they may affect the general performance and longevity of the plant. The longevity and profitability are strongly affected by the increasing incidence of grapevine wood diseases (GWD), intensified by the omission of good pruning practices and leading to an increasingly aggressive pruning. The purpose of this study is to provide an objective evaluation of the short- and mid-term implications of different pruning practices that differ in the degree of observation several of pruning principles.

Read More

HPLC and SEC analysis on the flavonoids and the skin cell wall material of Merlot berries reveals new insights into the study of the phenolic maturity

Anthocyanins and tannins contribute to important sensorial traits of red wines, such as color and mouthfeel attributes.

Read More

Isotopes to distinguish production system in Brazilian viticulture

Organic viticulture integrates practices aimed at foresting positive relationships among, vines, soil, and climate, with a focus on sustainability, social responsibility, and environmental protection. To safeguard production integrity, regulatory bodies worldwide conduct organic certifications in accordance with relevant regulations. Considering that agriculture practices influence the nitrogen, carbon and oxygen isotope composition, the study aimed to investigate the response of these isotopes in grape must cultivated by organic, biodynamic and conventional methods to distinguish between production systems.

Read More