GiESCO 2019 banner
IVES 9 IVES Conference Series 9 GiESCO 9 Evaluation of intra-vineyard spatial and temporal variability of leaf area index using multispectral images obtained by satellite (Landsat 8, Sentinel-2) and unmanned aerial vehicle platforms

Evaluation of intra-vineyard spatial and temporal variability of leaf area index using multispectral images obtained by satellite (Landsat 8, Sentinel-2) and unmanned aerial vehicle platforms

Abstract

Context and purpose of the study – Estimation of vineyard leaf area index (LAI) is an important aspect for the winegrowers. However, tracking and monitoring are difficult tasks due to time constraints. Satellite and unmanned aerial vehicle (UAV) imaging have become a practical monitoring method for LAI. Nevertheless, for a proper LAI determination, the image’s spatial resolution is a key factor, since low-resolution images are incapable of distinguishing between adjacent vines due to the large area covered in each pixel, this leads to misinterpretation or generalisation of vineyard information. The objective of this study was to evaluate the effect of spatial resolution on the accuracy of LAI estimation using different spatial resolutions: Landsat8 (30 m), Sentinel-2 (10 m) and UAV Multispectral images (0.05 m).

Material and methods – This study was carried out in a dryland vineyard cv. Pinotage situated in Stellenbosch, at the Welgevallen experimental farm (33°57’8” S, 18°52’26” E). The block (1.9 ha) has a North-South orientation and was planted on a West-South-West slope. The vines are trained on a sevenwire (moveable) hedge trellis, VSP (vertical shoot positioning) system. Three sources of remote sensing data, with different spatial resolutions, were chosen: i) Multispectral images acquired by a multi-rotor unmanned aerial vehicle (UAV) (spatial resolution 0.052 m); ii) Landsat 8 images (spatial resolution of 30 m) and iii) Sentinel-2A images (spatial resolution of 30 m). Images from these three sources were used to calculate the normalised difference vegetation index (NDVI) from the experimental site, and these values were compared with field measurements (empirical LAI model).

Results – Results obtained from low-resolution satellite images show a poor accuracy in the estimation of LAI on a plant scale. The image resolution of Landsat 8 and Sentinel-2 was not high enough to differentiate between adjacent groups of vines. The UAV multispectral images obtained the best agreement with the field LAI measurements, due to the high resolution (0.052 m pixel size). It is evident with the results obtained that UAV imaging is the most appropriate and accurate monitoring methodology since this technology providing enough information to estimate LAI per plant.

Download the PDF

DOI:

Publication date: September 27, 2023

Issue: GiESCO 2019

Type: Poster

Authors

Yolandi BARNARD1, Guillermo OLMEDO2, Albert STREVER1, Carlos POBLETE-ECHEVERRÍA1*

1 Department of Viticulture and Oenology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa
2 EEA Mendoza, Instituto Nacional de Tecnología Agropecuaria, Mendoza M5507EVY, Argentina

Contact the author

Keywords

Normalised Difference Vegetation Index (NDVI), Unmanned Aerial Vehicle (UAV), grid analysis, spatial variability

Tags

GiESCO | GiESCO 2019 | IVES Conference Series

Citation

Related articles…

Study of the sensory dimension of the wine typicality related to a terroir and crossing with their viticultural and oenological characteristics

The typicality of a product can be characterized by properties of similarity in relation to a type, but also by the properties of distinction.

Read More

Development of FTIR partial least squares models for polyphenol quantification in red wine during fermentation

Polyphenolic compounds are considered to have a major impact on the quality of red wines. Sensory impact, such as astringency and bitterness, stems directly from tannin composition. Thenceforth, quick analytical measurement of phenolic compounds appears to be a real challenge for winemaking monitoring and process control. Many methods were developed to analyzed polyphenols in wine, but they are time-consuming and require chemistry skills and equipment, not suitable for a rapid routine analysis. A reliable and rapid method to obtain this kind of measurement is Fourier Transform Infrared (FTIR) spectroscopy.

Read More

Polyphenol targeted and untargeted metabolomics on rosé wines : impact of protein fining on polyphenolic composition and color

Color is one of the key elements in the marketing of rosé wines[1]. Their broad range of color is due to the presence of red pigments (i.e. anthocyanins and their derivatives) and yellow pigments, likely including polyphenol oxidation products. Clarifying agents are widely used in the winemaking industry to enhance wine stability and to modulate wine color by binding and precipitating polyphenols[2]. During this study, the impact of four different fining agents (i.e. two vegetal proteins, potatoe and pea proteins, an animal protein, casein, and a synthetic polymer, polyvinylpolypyrrolidone, PVPP) on Syrah Rose wine color and phenolic composition (especially pigments) was investigated. Color was characterized by spectrophotometry analysis using the CIELab system in addition to absorbance data. Fining using PVPP had the highest impact on redness (a*) and lightness (L*) parameters, whereas patatin strongly reduced the yellow component (b*) of the wine color. In parallel, the concentration of 125 phenolic compounds including 85 anthocyanins and derived pigments was determined by Ultra High Performance Liquid Chromatography coupled to elestrospray ionisaion triple-quadrupole Mass Spectrometry (UHPLC-QqQ-ESI-MS) in the Multiple Reaction Monitoring mode[3] .

Read More

Organic volatile compounds as suitable markers of grapevine response to defense elicitors in the vineyard

In greenhouse, emission of volatile organic compounds (VOC) by grapevine leaves has already been reported in response to the defence elicitor sulfated laminarin (PS3) [1]. In order to check that this response was not specific to PS3, experiments were conducted on Vitis cv Marselan plantlets with several other elicitors of different chemical structures: i.e. Bastid® (COS-OGA),

Read More

Microclimatic differences in fruit zone of vineyards on different elevations of ‘nagy-eged hill’ in eger wine region, Hungary

The Bull’s Blood of Eger (‘Egri Bikavér’) is one of the most reputed red wines in Hungary and abroad, produced in the Northeastern part of the country.

Read More