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Spectral and thermal data as a proxy for leaf protective energy dissipation under kaolin application in grapevine cultivars
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Orientador(es)
Resumo(s)
The dynamic effects of kaolin clay particle film
application on the temperature and spectral reflectance of
leaves of two autochthonous cultivars (Touriga Nacional
(TN, n=32) and Touriga Franca (TF, n=24)) were studied in
the Douro wine region. The study was implemented in 2017,
in conditions prone to multiple environmental stresses that
include excessive light and temperature as well as water
shortage. Light reflectance from kaolin-sprayed leaves
was higher than the control (leaves without kaolin) on all
dates. Kaolin’s protective effect over leaves’ temperatures
was low on the 20 days after application and ceased about
60 days after its application. Differences between leaves
with and without kaolin were explained by the normalized
maximum leaf temperature (T_max_f_N), reflectance at
400 nm, 532 nm, and 737 nm, as assessed through TN data.
The wavelengths of 532 nm and 737 nm are associated with
plant physiological processes, which support the selection
of these variables for assessing kaolin’s effects on leaves.
The application of principal component analysis to the
TF data, based on these four variables (T_max_f_N and
reflectances: 400, 532, 737 nm) selected for TN, explained
83.56% of data variability (considering two principal
components), obtaining a clear differentiation between
leaves with and without kaolin. The T_max_f_N and the reflectance at 532 nm were the variables with a greater
contribution for explaining data variability. The results
improve the understanding of the vines’ response to kaolin
throughout the grapevine cycle and support decisions
about the re-application timing
Descrição
Research Article
Palavras-chave
handheld spectroradiometer leaves reflectance leaves temperature thermal camera xanthophyll
Contexto Educativo
Citação
Open Agriculture. 2019; 4: 294–304
Editora
De Gruyter