A potential of the growth stage estimation for paddy rice by using chlorophyll absorption bands in the 400-1100 nm region

Abstract

The present study was carried out for the fundamental suggestion of the physical and chemical insight of the spectral change due to the phenological stage by using chlorophyll absorption bands in the 400-1100 nm region. The time-series spectra data during the cultivation period were measured at several sites in situ. The peak of the time-series second derivative spectra in the 660-700 nm region arose around the Day of Year (DOY): 220-230 and DOY:240-250 periods. These periods agree well with the active tillering stage and the heading, respectively. Additionally, the negative peak of the second derivative spectra in the DOY:230-240 accommodates the maximum tiller number stage. The time-series behavior of band shifts of peak wavelength in the 650-700 nm region corresponded to that of the intensity of second derivative spectra. These results indicate a possibility that the aggregation of chlorophyll molecules become stronger in the DOY:220-255 region with the increase of the chlorophyll concentration. Simultaneously, the blue shift of the DOY:255-260 period indicates that the aggregation becomes weaker according to the senescence of leaves. The result of band shift thus provides the insights of the change in the time-series intensities from the view of the chemical interaction of chlorophyll molecules in the rice leaf.