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…

Diagnosis of soil quality and evaluation of the impact of viticultural practices on soil biodiversity in a vineyard in southwestern France

Viticulture is facing two major changes – climate change and agroecological transition. In both cases, soil quality is seen as a lever to move towards a more sustainable viticulture. However, soil biological quality is little considered in the implementation of viticultural practices. Gascogn’Innov (2017-2022) is an Operational Group funded by the European Innovation Partnership for Agriculture. As such, it brings together winegrowers from the south-west of France, scientists, advisors and technicians, around a project focused on viticultural soil biological functioning and the design of technical routes more respectful toward soil heritage. To achieve this, the project aims to acquire references on the impact of viticultural practices on soil biology from a dynamic way, and to test a methodology to integrate information provided by the soil bioindicators to manage farming systems. A set of indicators of soil biological quality are evaluated in the project: microorganisms (bacteria and fungi abundance and diversity), fauna (abundance and diversity of nematodes and earthworms), physico-chemical characteristics, soil structure assessment and degradation rate of organic matter. Based on a network of 13 plots that have been subject to an initial diagnosis in 2017, several agronomical practices to restore soil fertility are experimented to redesign the cropping system (for instance plant cover, organic matter inputs, reduction of herbicides, mineral fertilizers). System redesign was made in collaboration by winegrowers and an interdisciplinary group of experts (agronomists, biologists). Several indicators are measured on vine and soil at each vintage to assess vine health and productivity. At the end of the project (2021), a final diagnosis was carried out. Gascogn’Innov allowed to create a regional database on the quality of wine-growing soils, which permitted to evaluate the effect of practices according to soil types. Especially, decreasing the intensity of tillage and increasing the duration and diversity of grass coverage tends to increase the abundance of all the organisms studied. This project confirmed the value of soil biological quality indicators to drive the sustainability of practices, but also highlighted the key-role of expertise, in both agronomy and soil biology, to help winegrowers understand and appropriate their soil quality diagnoses.

Influence of cover crops in a Tempranillo vineyard grown under the edaphoclimatic conditions of the Appellation of Origin Rueda

The way to manage the vineyard soils has certainly changed in Spain during the last years. Traditionally, the vineyards were tilled, but this growing technique has been replaced in some vineyards by the bare soil with herbicide

The maturation evolution of Chardonnay grapes intended to sparkling wine making in Dom Pedrito

However, the increase of sugar concentration in the grapes causes a decrease of desired organic acids which are positive for the production of sparkling wines. The aim of this study was to identify the optimal harvest period of ‘Chardonnay’ intended to sparkling wine making in Dom Pedrito, Campanha Gaúcha.

The science of fungi in grapevine: An essential new book covering all aspects of fungi in viticulture

Grapevine is one of the world’s most important cultivated plants, domesticated from the wild vine over 11,000 years ago. The fungi associated with it are doubtless as old as the plant itself. Despite their co-evolution with the vine over the centuries, it was only with the invention of the microscope in the seventeenth century that fungi started to be recognised.

Sustaining grape production under challenging climate change circumstances

Grapevines are an important economic crop grown in temperate climates of both hemispheres characterized by short‐term heat spells and heat waves