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Foliar Reflectance and Fluorescence Responses for Corn and Soybean Plants Under Nitrogen StressWe are investigating the use of spectral indices derived from actively induced fluorescence spectra and passive optical spectra. We examined the influence of photosynthetic pigment, carbon (C) and nitrogen (N) content on the spectral fluorescence and passive optical property characteristics of mature, upper leaves from plants provided different N fertilizer application rates: 20%, 50%, 100% and 150% of recommended N levels. A suite of optical, fluorescence, and biophysical measurements were collected on leaves from field grown corn (Zea mays L.) and soybean plants (Glycine max L.) grown in pots (greenhouse + ambient sunlight. Steady state laser-induced fluorescence emission spectra (5 nm resolution) were obtained from adaxial and abaxial surfaces resulting from excitation at single wavelengths (280, 380 or 360, and 532 nm). For emission spectra produced by each of these excitation wavelengths, ratios of emission peaks were calculated, including the red far-red chlorophyll fluorescence (ChlF) ratio (F685/F740) and the far-red/green (F740/F525) ratio. High resolution (< 3 nm) optical spectra (350-2500 nm) of reflectance, transmittance, and absorptance were also acquired for both adaxial and abaxial leaf surfaces. Species differences were demonstrated for several optical parameters. A 'red edge' derivative ratio determined from transmittance spectra [as the maximum first deivative, between 650-750 nm, normalized to the value at 744 nm, or Dmax/D744], was strongly associated with the C/N ratio (r(exp 2) = 0.90, P +/- 0.001). This ratio, calculated from reflectance spectra, was inversely related to chlorophyll b content (r(exp 2) = 0.91, P +/- 0.001) as was the ChlF (F685/F740) ratio obtained with 532 nm excitation (r(exp 2) = 0.76, P +/- 0.01). Discrimination of N treatment groups was possible with specific fluorescence band ratios (e.g., F740/F525 obtained with 380 nm excitation). Higher ChlF and blue-green emissions were measured from the abaxial leaf surfaces. Abaxial surfaces also produced higher reflectances, in general, in the 400-800 nm spectrum.
Document ID
20040110257
Acquisition Source
Goddard Space Flight Center
Document Type
Conference Paper
Authors
Middleton, E. M.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Campbell, P. K. Entcheva
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Corp, L. A.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Butcher, L. M.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
McMurtrey, J. E.
(Department of Agriculture Beltsville, MD, United States)
Date Acquired
August 21, 2013
Publication Date
January 1, 2003
Subject Category
Life Sciences (General)
Meeting Information
Meeting: Ecological Society of America Annual Meeting
Location: Savannah, GA
Country: United States
Start Date: August 2, 2003
End Date: August 8, 2003
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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