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Intercepted photosynthetically active radiation in wheat canopies estimated by spectral reflectanceThe interception of photosynthetically active radiation (PAR) was evaluated relative to greenness and normalized difference (MSS 7-5/7+5) for five planting dates of wheat for 1978-79 and 1979-80 in Phoenix. Intercepted PAR was calculated from a model driven by leaf area index and stage of growth. Linear relationships were found between greenness and normalized difference with a separate model representing growth and senescence of the crop. Normalized difference was a significantly better model and would be easier to apply than the empirically derived greenness parameter. For the leaf area growth portion of the season the model between PAR interception and normalized difference was the same over years, however, for the leaf senescence the models showed more variability due to the lack of data on measured interception in sparse canopies. Normalized difference could be used to estimate PAR interception directly for crop growth models.
Document ID
19840013859
Acquisition Source
Legacy CDMS
Document Type
Contractor Report (CR)
Authors
Hatfield, J. L. (Kansas State Univ. Manhattan, KS, United States)
Asrar, G. (Kansas State Univ. Manhattan, KS, United States)
Kanemasu, E. T. (Kansas State Univ. Manhattan, KS, United States)
Date Acquired
September 4, 2013
Publication Date
September 1, 1982
Subject Category
Earth Resources And Remote Sensing
Report/Patent Number
NASA-CR-171758
E84-10109
NAS 1.26:171758
CONTRIB-82-559-J
SR-M2-04342
Accession Number
84N21927
Funding Number(s)
PROJECT: PROJ. AGRISTARS
CONTRACT_GRANT: NAS9-16457
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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