USE OF NONDESTRUCTIVE SPECTROSCOPY TO ASSESS CHLOROPHYLL AND NITROGEN IN FRESH LEAVES

anthocyanins-free species. The best indices were the indices developed with the Chl-related OW either from visible or red edge region in combination with a reference wavelength (RW) from the near infrared (NIR) region (750 – 1100 nm) that was sensitive to leaf texture but insensitive to Chl as the form of a simple ratio (RRW/ROW) or normalized difference vegetation index (RRW – ROW)/ ( RRW + ROW). With RW, the differences in reflectance in the visible and red edge regions caused by variation in leaf texture or other optical properties could be eliminated. This was particularly important when the R2 of a single-wavelength index was small for Chl or N measurement (e.g. R2<0.8000 for Chl or R2<0.6000 for N). Parameters used by hand-held Chl meters (CCM-200, SPAD-502, and CM-1000) affected their accuracy for Chl and N assessment. Our results showed that SPAD-502 wa