Fluorescence remote sensing and stress detection in the invasive grass, Phragmites australis.
Naumann, Julie *,1, Young, Donald1, Anderson, John1, 1 Department of Biology, Richmond, VA, USA
ABSTRACT- Effects of salinity and drought on photosynthesis, water relations, and chlorophyll fluorescence were used to evaluate stress in Phragmites australis (common reed). Our study examined natural populations in the field and plants grown from rhizomes in glasshouse experiments. In the field, dark-adapted leaves were excited at 630nm and analyzed using a leaf chamber fluorometer (LICOR). In the laboratory, plants of varying degrees of stress were excited with light at 455 and 680 nm, and emission spectra were evaluated with an Horiba Fluorolog luminescence spectrometer between 625-800 and 700-800 nm, respectively. There was a statistically significant temporal change in fluorescence characteristics, both in field measurements and glasshouse experiments as both salinity and drought increased. These changes were detectable before stress effects were visually apparent (i.e. wilted, senescent leaves, etc). Photosynthetic and water potential measurements also decreased indicating the onset of stress, beginning at 10 ppt salinity, and −1.5 MPa, respectively. Canonical correspondence analyses identified environmental parameters that contributed most to the changes in physiological measurements. This application of remote sensing successfully provided an assessment of the physiological limits of optimal Phragmites performance with respect to specific environmental stresses. Remote detection of plant stress utilizing fluorescence techniques, especially of fluorescence emission spectra, may be applicable for assessing the potential population expansion of invasive species that form extensive monocultures. −
Key words: Phragmites, fluorescence, invasive species
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