TITLE:
Water Stress Early Detection of Eggplant Plants by Hyperspectral Fluorescence Spectroscopy
AUTHORS:
Amara Kamate, Penetjiligué Adama Soro, Emma Georgina Zoro-Diama, Kedro Sidiki Diomande, Adjo Viviane Adohi-Krou
KEYWORDS:
Chlorophyll Fluorescence, Eggplant, Water Stress, Water Deficiency, PLS-DA
JOURNAL NAME:
Open Journal of Applied Sciences,
Vol.13 No.3,
March
21,
2023
ABSTRACT: Water stress early detection is essential for precision farming to
improve crop productivity and product quality. The methods usually used are
destructive, long and expensive. In this
work, we used hyperspectral chlorophyll fluorescence technology as a
rapid, non-destructive approach to detect the water deficiency of eggplant
plants using their spectral footprint. So, an experiment was made on 54
eggplant plants subjected to three water treatments: normal irrigation (T100),
intermediate irrigation (T50) and no irrigation (T0). The
fluorescence spectra were acquired in
vivo and in situ using a USB4000
spectrometer from Ocean optics. For the classification of the plants subjected
to three water treatments, we used three pretreatments of the raw hyperspectral data in order to suppress the non-informative
variability present in these spectra
and to obtain robust models. These are the Savitzky-Golay smoothing (SG), the standard normal variable (SNV) and the first derivative of Savitzky-Golay (SG-D1). The preprocessed data were then subjected
to two partial least squares discriminant analyses (PLS-DA): Hard PLS-DA
and Soft PLS-DA. These statistical approaches are suitable for large samples as
it reduces the dimensionality of the data but improves the accuracy of the
prediction. The SG-D1 combined with the Soft PLS-DA gave the best
discrimination of plants with scores of sensitivity, specificity and total
efficiency respectively of 97.33%, 94% and 95% for calibration, 6 days after
hydric stress induction. For the plants used for the prediction, the scores are
86%, 91% and 90% respectively. This study shows that hyperspectral chlorophyll
fluorescence spectroscopy is a fast and non-destructive technology allowing
early detection of water stress in eggplant plants.