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Proceedings Paper

Effects of nitrogen stress in grass swards on evolution of ground cover and spectral characteristics of leaf strata
Author(s): A.G.T. Schut; J.J.M.H. Ketelaars
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Paper Abstract

The effects of nitrogen (N) application level on temporal development of ground cover (GC) and reflection curves of leaf strata within the canopy were studied with an experimental imaging spectroscopy set-up. This set-up has a high spatial (0.16-0.26mm2) and spectral resolution (5-13 nm) within the 405-1650 nm range and can distinguish leaves in height and leaf angle related intensity classes from 1 meter distance. Between June and late October 2000, a greenhouse experiment was conducted with Lolium perenne L. mini swards with 5 N treatments (0, 30, 60, 90, 120 kg N per cut), 4 cutting dates and 3 replicates. Images were recorded twice a week. Ground cover of green material increased up to cutting dates. Nitrogen treatments could be separated by development of GC and the width of the broad chlorophyll absorption band of leaves around 680 nm (CAW), with small changes in GC and CAW for the 0 N and large changes for high N treatments. Two weeks after cutting, CAW reached its maximum with a subsequent decrease for the lower N treatments in the last week before cutting. The width of the CAW showed a unique relation with the relative yield deficit for all cutting dates (R2equals0.95). Changes in edge position with vertical position in the canopy were stronger for blue edge and green edge when compared to red edge. Darker green leaves were present at the bottom of the canopy and lighter green leaves at the top.

Paper Details

Date Published: 28 January 2002
PDF: 8 pages
Proc. SPIE 4542, Remote Sensing for Agriculture, Ecosystems, and Hydrology III, (28 January 2002); doi: 10.1117/12.454194
Show Author Affiliations
A.G.T. Schut, Plant Research International BV (Netherlands)
J.J.M.H. Ketelaars, Plant Research International BV (Netherlands)

Published in SPIE Proceedings Vol. 4542:
Remote Sensing for Agriculture, Ecosystems, and Hydrology III
Manfred Owe; Guido D'Urso, Editor(s)

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