Physical and Mechanical Properties of Catalpa bungei Clones and Estimation of the Properties by Near-Infrared Spectroscopy

Air-dry density, modulus of rupture (MOR), modulus of elasticity (MOE), compressive strength parallel to grain, and hardness of Catalpa bungei clones were investigated in this study with feasibility of predicting these properties by near-infrared (NIR) spectroscopy. The best candidate ‘Luoqiu 3’ has been selected from three clones based on wood physical and mechanical property indices. Lower values of wood physical and mechanical properties have been found in the corewood compared to the outerwood. There were significant positive correlations between the air-dry density and mechanical properties. Information from cross section for air-dry density, compressive strength parallel to grain, and hardness yielded prediction models with better effects, along with the best MOR and MOE modeling effects resulted from average sections’ spectra collection. Multiplicative scatter correction (MSC) + Savitzky-Golay (S-G) smoothing method has been proved to be the most applicable way. In addition, the predictions from five-point sampling method were slightly better than three-point one. Overall, results suggest NIR spectroscopy was viable to predict the physical and mechanical properties of C. bungei clones with methods developed in this study proved effective in preliminary screening.