Abstract
This study describes a method for evaluating the change in the water content of leaves by using visible and near infrared spectral analyses. The spectral behaviors within the 400-1100 nm region that corresponded to drought in the sample leaves were investigated using a spectrometer. Bands in the 470-490, 600-620, and 650-690 nm regions that are due to chlorophyll absorption were identified. Importantly, these bands were blueshifted by about 6-9 nm and showed decreased intensities. In particular, the band in the 650-690 nm region correlated to the water content with a coefficient of determination (R2) of 0.74. The spectral patterns of the loadings, which were calculated by principal component analysis (PCA), appeared similar to those of the second derivative spectra. Furthermore, the score of the first principal component obtained by PCA was clearly separated at the water content value of 48.1%. Therefore, the results provide a chemical understanding of band behavior in the 400-1100 nm region and suggest that PCA may support the evaluation of water content and stress in leaves by using this spectral region.
