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Chlorophyll Fluorescence Emissions of Vegetation Canopies From High Resolution Field Reflectance SpectraA two-year experiment was performed on corn (Zea mays L.) crops under nitrogen (N) fertilization regimes to examine the use of hyperspectral canopy reflectance information for estimating chlorophyll fluorescence (ChlF) and vegetation production. Fluorescence of foliage in the laboratory has proven more rigorous than reflectance for correlation to plant physiology. Especially useful are emissions produced from two stable red and far-red chlorophyll ChlF peaks centered at 685V10 nm and 735V5 nm. Methods have been developed elsewhere to extract steady state solar induced fluorescence (SF) from apparent reflectance of vegetation canopies/landscapes using the Fraunhofer Line Depth (FLD) principal. Our study utilized these methods in conjunction with field-acquired high spectral resolution canopy reflectance spectra obtained in 2004 and 2005 over corn crops, as part of an ongoing multi-year experiment at the USDA/Agriculture Research Service in Beltsville, MD. A spectroradiometer (ASD-FR Fieldspec Pro, Analytical Spectral Devices, Inc., Boulder, CO) was used to measure canopy radiances 1 m above plant canopies with a 22deg field of view and a 0deg nadir view zenith angle. Canopy and plant measurements were made at the R3 grain fill reproductive stage on 3-4 replicate N application plots provided seasonal inputs of 280, 140, 70, and 28 kg N/ha. Leaf level measurements were also made which included ChlF, photosynthesis, and leaf constituents (photosynthetic pigment, carbon (C), and N contents). Crop yields were determined at harvest. SIF intensities for ChlF were derived directly from canopy reflectance spectra in specific narrowband regions associated with atmospheric oxygen absorption features centered at 688 and 760 nm. The red/far-red S F ratio derived from these field reflectance spectra successfully discriminated foliar pigment levels (e.g., total chlorophyll, Chl) associated with N application rates in both corn crops. This canopy-level spectral ratio was also positively correlated to the foliar C/N ratio (r = 0.89, n = go), as was a leaf-level steady state fluorescence ratio (Fs/Chl, r = 0.92). The latter ratio was inversely correlated with crop grain yield (Kg 1 ha) (r = 0.9). This study has relevance to future passive satellite remote sensing approaches to monitoring C dynamics from space.
Document ID
20080045451
Acquisition Source
Goddard Space Flight Center
Document Type
Conference Paper
Authors
Middleton, E. M.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Corp, L. A.
(Science Systems and Applications, Inc. Lanham, MD, United States)
Daughtry, C. S. T.
(Department of Agriculture Beltsville, MD, United States)
Campbell, P. K. Entcheva
(Maryland Univ. Baltimore County Catonsville, MD, United States)
Date Acquired
August 24, 2013
Publication Date
July 29, 2006
Subject Category
Earth Resources And Remote Sensing
Meeting Information
Meeting: International Geoscience and Remote Sensing Symposium (IGARSS''06)
Location: Denver, CO
Country: United States
Start Date: July 29, 2006
End Date: August 4, 2006
Distribution Limits
Public
Copyright
Other

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