INVESTIGADORES
LAGORIO MarÍa Gabriela
congresos y reuniones científicas
Título:
Non-destructive methods for assessment of senescence photochemistry: from leaf to stand level
Autor/es:
GABRIELA B. CORDON; MARÍA GABRIELA LAGORIO; JOSÉ PARUELO
Lugar:
Córdoba
Reunión:
Congreso; 16th International Congress on Photobiology; 2014
Institución organizadora:
International Union of Photobiology
Resumen:
Senescence is a key process in
plants controlled by onthogeny but also by environmental factors. A reduction
in chlorophyll concentration and in photosynthetic activity characerize senescence.
The consequence of senescence of different functional aspects is critical to
understant the influence of diverse stress factors.
In this study senescence was evaluated in two grasses (Setaria italica a C4 species and Avena sativa C3 species) by non-destructive methods: reflectance
spectroscopy and chlorophyll fluorescence to evaluate changes in pigments and
on radiation use efficiency (RUE) and interception. Measures were performed at
two level: individual leaves and the whole canopy.
Both species were seeded and grown in pots. Radiance
and reflectance spectra were recorded with a portable spectroradiometer
FieldSpec Pro FR ASD equipped with leaf-clip accessories. From them, two
spectral indices: PRI (a measure of RUE) and NDVI (a measure of photosynthetic
active radiation absorption) were calculated. Fraunhofer Line Discrimination
(FLD) method was used to extract the sun induced fluorescence (SIF) from the
small canopy in the telluric O2-A absorption line (760 nm). Photochemical parameters
(Fv/Fm, fPSII, qP, qNP, QNP) were obtained with a modulated fluorometer Hansatech. Measurements
were performed on non-detached leaves. Pigments contents were also determined [1].
Parallel to the decrease in
total chlorophyll content (nmol/cm2) an increase in carotenoid/total
chlorophyll ratio (Car/Chlor) was observed. The leaf PRI values decreased over
time for both studied species. Canopy level values were more sensitive. NDVI values
were less responsive. Canopy SIF (760 nm) decreased in time. We found that canopy level PRI correlated linearly and directly with SIF, Fv/Fm and fPSII for Avena
sativa, Setaria italica and both
species combined; while inversely related with qNP, QNP and Car/Chlor.