Effect of Nitrogen and Endophytic Bacteria on Biophysical and Spectral Parameters of Wheat Canopy
2010
Adami, M. | Rudorff, B. F. T. | Breunig, F. M. | Ponzoni, F. J. | Galvão, L. S. | Moreira, M. A. | Freitas, J. G. | Sala, V Marino Rodrigues
Nitrogen (N) is the primary limiting factor to increase wheat (Triticum aestivum L.) yield in Brazil, and the use of N-fixing agents might be an alternative to increase wheat production. A field experiment was conducted in 2006 in São Paulo State, Brazil, with three N rates (0, 60, and 120 kg ha⁻¹) and three endophytic bacteria (IAC-HT-11, IAC-HT-12, and IAC-AT-8) to evaluate their combined impact on biophysical (leaf area index [LAI] and grain yield) and spectral parameters (normalized difference vegetation index [NDVI], absorption band parameters) of wheat and to determine the spectral parameters that best correlated with LAI and grain yield. Leaf area index and canopy spectral reflectance measurements were made at jointing, heading, and ripening growth stages for this purpose. The statistical relationships between biophysical and spectral parameters were evaluated within and among the treatments. Statistical results showed that the N rates significantly affected biophysical and spectral parameters. Bacteria inoculation presented a significant effect only on grain yield, which is consistent with results reported in the literature. The NDVI, followed by absorption band parameters PB and AB at 1205 nm, provided the best estimates of LAI and grain yield during the heading stage, indicating that it may be the best stage for remote sensing–based yield mapping.
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