Spectral components analysis equations and their application to rice

Remote spectral observations expressed as vegetation indices (VI) provide information about the photosynthetic size and net assimilate in plant canopies that permit inferences about crop growth and economic yield. The interrelationships are expressed in equation form and are applied to data from an experiment conducted in 1987 at Tsukuba, Japan, with Japonica-type paddy rice (Oryza Sativa L.). The vegetation indices used were the perpendicular (PVI) and normalized difference (NDVI). The equations were validated by the data. Functional relations were predominantly linear. The seasonal cumulations equivalent to area under seasonal PVI and NDVI versus time curves (spectral profiles) were much more closely related to economic yield than were PVI and NDVI averaged for three dates surrounding heading. It is concluded that the spectral components analysis (SCA) equations permit interpretation of spectral observations of rice that are consistent with its growth and yield in the paddy.