Potential use of NIR spectroscopy to identify Cryptomeria japonica varieties from southern Brazil

Cryptomeria japonica has good potential for forest plantations in southern Brazil. Plants of Japanese origin have different adaptations to cold temperatures in the initial phase, and mean annual growth is related to seed origin and the characteristics of the growing site. Because of the differences in the adaptation and growth between varieties with different origins, it is important to be able to obtain this information precisely, for which a fast method like infrared spectroscopy can be a good alternative. Needles and wood of six origins were analyzed. Infrared analyses were performed in a spectrophotometer equipped with an integrating sphere and operating in reflectance mode. There were 64 scans with a resolution of 4 cm⁻¹ and a spectral range of 10,000–4000 cm⁻¹. For each variety, 30 spectra were collected. The mean spectra of the plants of different origin, obtained from needle and wood samples, showed similarity. Pre-processing data by taking the second-derivative was the most efficient, and near-infrared spectroscopy can be applied to distinguish the six C. japonica varieties based on needles and wood.