Grain sorghum leaf reflectance and nitrogen status

Abunyewa, A.A. and Ferguson, R.B. and Wortmann, C.S. and Mason, S.C. (2016) Grain sorghum leaf reflectance and nitrogen status. African Journal of Agricultural Research, 11 (10). pp. 825-836.

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Abstract

Nitrogen deficiency is a common but readily managed constraint to grain yield. A quick and nondestructive detection of crop N status using remote sensing could be a means to increased N use efficiency. Research was conducted in a greenhouse in 2006 at the University of Nebraska-Lincoln to establish the relationship of spectral reflectance with N status in leaves of grain sorghum, to develop indices for interpretation of the results and to predict chlorophyll content. Nitrogen stress decreased chlorophyll meter reading and leaf N content, but increased leaf and canopy reflectance. The SPAD values were significantly increased by both water and N stress. Reciprocal reflectance in the green range (549 to 560 nm), and red edge range (710 to 718 nm) wavelength of the spectrum were good indicators of N stress. The best fit regression between leaf chlorophyll content and the indices in the green and red edge wavebands were linear with an R2 of 0.76 to 0.79. A model calibrated using these wavelengths minus reciprocal reflectance of NIR (750 nm), predicted leaf chlorophyll content with root mean square error (RMSE) ranging between 52 and 56 mg m-2, and reduced the intercept of the model from 312 to 35 mg m-2 in the green range and 486 to 21 mg m-2 in the red edge. Future studies will be conducted to evaluate the effectiveness of the indices at the canopy level of grain sorghum.

Item Type: Article
Uncontrolled Keywords: Chlorophyll, grain sorghum, nitrogen, red edge, reflectance, SPAD
Author Affiliation: Department of Agroforestry, Faculty of Renewable Natural Resources, Kwame Nkrumah University of Science and Technology, Ghana
Subjects: Crop Improvement
Divisions: Sorghum
Depositing User: Mr T L Gautham
Date Deposited: 04 May 2016 10:40
Last Modified: 04 May 2016 10:40
URI: http://eprints.icrisat.ac.in/id/eprint/14304

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