Abstract:

The correlation between near infrared spectroscopy (NIR) and X-ray diffraction (XRD) determined crystallinity of Slash Pine wood, and the effect of reducing and selecting spectral wavelengths on prediction ability by near infrared spectroscopy were investigated in this paper. The results showed that there are strong correlations between NIR predicted and X-ray diffraction determined crystallinity based on reducing the spectral range, the correlation coefficients are 0.943 with low RMSEP values based on the reduced spectral ranges between 2 000～2 500 nm. Using smaller wavelength ranges (1 400～1 660 nm or 2 020～2 250 nm) and/or even selecting certain wavelengths consistent with known chemical absorptions did not have a significant effect on the results of NIR prediction. The result shows that the NIR prediction model based on only several spectral variables yielded high r value at 0.930 with low RMSEP value, indicating it is important to ensure that the selected wavelengths are consistent with known chemical absorptions in NIR modeling, and it's feasible to use smaller and lighter portable spectrometer in field applications for tree breeding programs and for wood optimal utilization in the near future.

Key words: near infrared spectroscopy, X-ray diffraction, wood, crystallinity, correlation