|Estell, Richard - Rick|
Submitted to: Journal of Applied Spectroscopy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/11/2006
Publication Date: 8/1/2006
Citation: Danielson, T.L., Obeidat, S., Rayson, G.D., Anderson, D.M., Fredrickson, E.L., Estell, R.E. 2006. Photoluminescent distinction among plant life forms using phosphate buffered saline extract solutions. Applied Spectroscopy. 60:800-807.
Interpretive Summary: Six desert plant species representing two grasses, mesa dropseed (Sporobolus flexuosus) dropseed), and tobosa (Pleuraphis mutica), two weeds (forbs), spectacle pod (Dimorphocarpa wislizenii) and pale globmallow (Sphaeralcea incana) and two woody plants (shrubs), tarbush (Flourensia cernua) leaves and stems and fourwing saltbush (Atriplex canescens) leaves and stems were prepared for analysis using an optical technique (photoluminescence) to attempt and detect differences among the six species. The data (370 to 600 nm emission spectra) obtained from acidic (pH 2.2) neutral (pH 7.5) and basic (pH 12.5) phosphate buffered saline (PBS) extracts of the ground plant material, when excited at 365 nm, produced six uniquely different spectral signatures as determined using a mathematical procedure called principal component analysis (PCA). Besides being environmentally friendly PBS was ineffective in extracting chlorophyll. When chlorophyll is effectively extracted its red fluorescence will mask fluorescence coming from the blue and green regions of the visible spectrum, an area of fluorescence responsible for differences among plant species.
Technical Abstract: Photoluminescence of plant extract solutions has been investigated for discrimination of plant life forms (grasses, forbs and shrubs) using principle componet analysis (PCA). Clippings from each of six plant species representing three different plant life forms potentially found in the diets of free-ranging herbivores in the Chihuahuan Desert of North America were investigated for possible discernment. These plants included Sporobolus flexuosus (mesa dropseed, a grass), Pleuraphis mutica (tobosa, a grass), Dimorphocarpa wislizenii (spectacle pod, a forb), Sphaeralcea incana (pale globemallow, a forb), Flourensia cernua leaves (tarbush, a shrub), and Atriplex canescens leaves and stems (fourwing saltbush, a shrub). Emission spectra (370-600 nm) from phosphate buffered saline (PBS) extract solutions (pH 2.2, 7.5 and 12.5) were recorded for each plant with excitation at 365 nm. Use of PBS minimized chlorophyll interference. Discernment among plant life forms within these plant species was achieved.