Dagricultural biophysical parameters and the tasseled cap transformation for RapidEye data

Deriving information about the chlorophyll (Chl) and/or nitrogen (N) status of senescent wheat using spectral indices obtained from satellite data can be useful to predict plant water status, salvageable N, N use efficiency, grain protein content and dry-down rates. RapidEye's Tasseled Cap Feature Yellowness (YEL) corresponds to the reflectance characteristics of senescent crops, with relatively higher reflectance in the visible portion of the spectrum due to chlorophyll breakdown, and lower reflectance in the NIR range due to cell structure decomposition. The goal of this study was to evaluate the potential and accuracy of YEL, in comparison to the Plant Senescence Reflectance Index (PSRI), for estimating chlorophyll and nitrogen concentration of senescent winter and spring wheat (Triticum aestivum L.). Preliminary results showed that YEL had a higher potential to estimate Chl in senescent winter wheat in comparison to PSRI, while PSRI demonstrated stronger correlations to Chl in senescent spring wheat than YEL. For the estimation of N concentration, YEL yielded much stronger, statistically significant correlations and a higher accuracy than PSRI. Results indicated the capability of YEL to predict both Chl and N concentration, probably attributable to the additional information provided by the Red-edge band. YEL may be used to characterize in-field senescence status variations, potentially providing ancillary information for the assignment of precision management zones related to yield and wheat quality parameters.