1. Optimising three-band spectral indices to assess aerial N concentration, N uptake and aboveground biomass of winter wheat remotely in China and Germany.
- Author
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Li, Fei, Mistele, Bodo, Hu, Yuncai, Chen, Xinping, and Schmidhalter, Urs
- Subjects
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MATHEMATICAL optimization , *BIOMASS , *WINTER wheat , *PLANT canopies , *NITROGEN - Abstract
Abstract: Remotely and accurately quantifying the canopy nitrogen status in crops is essential for regional studies of N budgets and N balances. In this study, we optimised three-band spectral algorithms to estimate the N status of winter wheat. This study extends previous work to optimise the band combinations further and identifies the optimised central bands and suitable bandwidths of the three-band nitrogen planar domain index (NPDI) for estimating the aerial N uptake, N concentration and aboveground biomass. Analysis of the influence of bandwidth change on the accuracy of estimating the canopy N status and aboveground biomass indicated that the suitable bandwidths for optimised central bands were 37nm at 846nm, 13nm at 738nm and 57nm at 560nm for assessing the aerial N uptake and were 37nm at 958nm, 21nm at 696nm and 73nm at 578nm for the assessment of the aerial N concentration and were 49nm at 806nm, 17nm at 738nm and 57nm at 560nm for the estimation of aboveground biomass. The optimised three-band NPDI could consistently and stably estimate the aerial N uptake and aboveground biomass of winter wheat in the vegetative stage and the aerial N concentration in the reproductive stage compared to the fixed band combinations. With suitable bandwidths, the broadband NPDI demonstrated excellent performance in estimating the aerial N concentration, N uptake and biomass. We conclude that the band-optimised algorithm represents a promising tool to measure the improved performance of the NPDI in estimating the aerial N uptake and biomass in the vegetative stage and the aerial N concentration in the reproductive stage, which will be useful for designing improved nitrogen diagnosis systems and for enhancing the applications of ground- and satellite-based sensors. [Copyright &y& Elsevier]
- Published
- 2014
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