Estimating mechanical properties and specific gravity for five-year-old Eucalyptus tereticornis having broad moisture content range by NIR spectroscopy

Near infrared spectroscopy coupled with multivariate data analysis has been used to predict the specific gravity, modulus of rupture, modulus of elasticity, and fiber stress at elastic limit in bending tests on radial and tangential strip wood samples obtained from five-year-old Eucalyptus tereticornis. Moisture content of samples was 6-21% for bending test and 7-16% for specific gravity. Partial least squares regression calibrations were developed for each wood property. Calibrations had good relationships between values measured in laboratory and NIR predicted values obtained from small clear samples. The coefficient of determination (R(2)) for calibration ranged from 0.76 to 0.83 and for prediction (R(2)(p)) it was between 0.58 and 0.77. Both radial and tangential faces are equally suited for calibration (for radial face R(2) was 0.77-0.83 and for tangential it was 0.76-0.83). Standard errors of predictions were slightly higher compared to standard error of calibration.