Skip to main content
ARS Home » Research » Publications at this Location » Publication #116926
Title: A THREE-BAND, TWO-DIMENSIONAL REFLECTANCE INDEX FOR WHEAT AND COTTON CANOPYCHLOROPHYLL CONTENT

Author
item Clarke, Thomas
item Barnes, Edward
item Pinter Jr, Paul
item Kimball, Bruce
item HABERLAND, J - UNIV OF ARIZONA
item RILEY, E - UNIV OF ARIZONA
item THOMPSON, T - UNIV OF ARIZONA

Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 10/23/2000
Publication Date: 11/9/2000
Citation: Clarke, T.R., Barnes, E.M., Pinter Jr, P.J., Kimball, B.A., Haberland, J.A., Riley, E.A., Thompson, T.L. 2000. A three-band, two-dimensional reflectance index for wheat and cotton canopychlorophyll content. Agronomy Abstracts. pp 27.

Interpretive Summary:

Technical Abstract: Plant response to nutrient availability manifests itself as shifts in spectral reflectance resulting from changing chlorophyll concentration. Reflectance at the far-red (F) wavelength of 720nm was normalized to the near-infrared (NIR) reflectance at 790nm to produce a signal sensitive to canopy chlorophyll content. However, the range of possible signal responses is proportional to the amount of vegetation in the sensors' field of view. It is necessary to have some measure of canopy density in order to evaluate the signal response in terms of actual crop condition. Therefore a two-dimensional approach was used, with canopy density estimated by red (R) and NIR reflectances providing one dimension and the chlorophyll signal response as the other dimension. The method was tested on wheat reflectance data collected in 1997 and cotton data from 1999. The best result for the wheat crop was achieved using the Ratio Vegetation Index as the canopy density dimension and the ratio of NIR/F as the chlorophyll0sensitive dimension. Correlation with SPAD measurements was good just before stem elongation, and again after flowering. For cotton, good results were achieved using a Normalized Difference Vegetation Index and the normalized difference between NIR and F as the two dimensions.