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Title: Effects of leaf excision and sample storage methods on spectral reflectance by foliage of Giant Reed, Arundo donax

item SUMMY, KENNETH - Texas-Pan American University
item LIEMAN, JONATHAN - Texas-Pan American University
item MAMACHEN, ARASH - Texas-Pan American University
item GANDY, YURIDIA - Texas-Pan American University
item MAMACHEN, ASHISH - Texas-Pan American University
item Goolsby, John
item Moran, Patrick

Submitted to: Subtropical Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/20/2012
Publication Date: 1/18/2013
Citation: Summy, K.R., Lieman, J., Mamachen, A., Gandy, Y.P., Mamachen, A., Goolsby, J., Moran, P.J. 2013. Effects of leaf excision and sample storage methods on spectral reflectance by foliage of Giant Reed, Arundo donax. Subtropical Plant Science. 63:54-64.

Interpretive Summary: Arundo donax is an invasive weed in the Rio Grande Basin. A hand held device which measures the reflectance of light waves was used to measure water stress in A. donax leaves. Clipped leaves held in sealed Ziploc bags for 72-96 hours were compared to living leaves growing on the plant. The clipped leaves showed a similar pattern of light reflectance as live leaves. This finding indicates that A. donax leaves can be harvested from the field and held for up to 3 days in sealed bags for testing. This allows researchers to harvest leaves over a period of several days and return them to the laboratory for testing. Light wavelength testing can be used to detect stress in the plant, such as damage from the A. donax biological control insects.

Technical Abstract: Research was conducted to evaluate the effects of leaf excision and sample storage methods on spectral reflectance by foliage of giant reed, Arundo donax, an invasive weed which has caused extensive damage in many areas of the Rio Grande Basin in Texas and Mexico. Within 24 hours of excision, A. donax leaves exposed to ambient laboratory conditions (room temperature under natural lighting conditions) exhibited two trends indicative of physiological stress: 1) small but significant increases in reflectance of blue and red wavelengths (400-500 nm and 600-700 nm, respectively), and 2) a substantial reduction in reflectance of near-infrared (NIR) wavelengths (700-1,100 nm). A similar but less pronounced trend was evident among leaf samples held within conventional paper sacks. Leaf samples held within sealed plastic bags (Glad-Bags) under two types of lighting conditions (natural light and artificial darkness) and temperature regimes (room temperature vs. artificially cooled) exhibited slight but significant increases in both visible and NIR wavelengths (a trend that was also evident in attached foliage), although no evidence of physiological stress was detected during a 96-hour observation period. These trends indicate that accurate spectral measurements may be obtained from samples of A. donax foliage for periods up to 72-96 hours following excision, if such samples are transported and maintained in suitable containers designed to minimize effects of desiccation.