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Color changes were tested and compared for heat-treated Paulownia tomentosa and Pinus koraiensis wood treated with hot oil or hot air for further utilization of these species. Hot oil and hot air treatments were conducted at 180, 200, and 220 °C for 1, 2, and 3 h. Heat-treated wood color changes were determined using the CIE-Lab color system. Weight changes of the wood before and after heat treatment were also determined. The weight of the oil heat-treated wood increased considerably but it decreased in air heat-treated wood. The oil heat-treated samples showed a greater decrease in lightness (L*) than air heat-treated samples. A significant change in L* was observed in Paulownia tomentosa. The red/green chromaticity (a*) of both wood samples increased at 180 and 200 °C and slightly decreased at 220 °C. The yellow/blue chromaticity (b*) in both wood samples increased at 180 °C, but it rapidly decreased with increasing treatment durations at 200 and 220 °C. The overall color change (ΔE*) in both heat treatments increased with increasing temperature, being higher in Paulownia tomentosa than in Pinus koraiensis. In conclusion, oil heat treatment reduced treatment duration and was a more effective method than air heat treatment in improving wood color.

The anatomical characteristics in the culms of the four promising Indonesian bamboo species, including Dendrocalamus asper, Dendrocalamus giganteus, Bambusa vulgaris var. vulgaris, and Bambusa vulgaris var. striata, were investigated to produce an identification key and quality indices for further effective utilization. The crystalline properties of the bamboo culm were determined using X-ray diffraction analysis. Dendrocalamus asper and Bambusa vulgaris var. striata showed vascular bundle type IV, while Dendrocalamus giganteus and Bambusa vulgaris var. vulgaris displayed vascular bundle type III. The vascular bundle density in the bamboo culms increased from the bottom to the top part and was higher in the outer part than in the inner part. The fiber portion and length in the outer part were higher than those in the inner part, opposite of those in the parenchyma portion. Dendrocalamus giganteus had the largest vessel and parenchyma diameter, while Bambusa vulgaris var. vulgaris had the smallest. Bambusa vulgaris var. vulgaris had the longest parenchyma, while Bambusa vulgaris var. striata and Dendrocalamus giganteus had the shortest. The outer part of the four bamboo culms showed higher relative crystallinity than the inner part. All anatomical parameters, except for crystallite width, showed a variation in the radial direction of the four bamboo culms but did not show a consistent tendency vertically. This study revealed that the anatomical properties were different between bamboo species and could be used for species identification and quality evaluation indices of the culms.

The anatomical features of three valuable commercial Gigantochloa bamboo species growing in Indonesia, including G. pseudoarundinacea, G. apus, and G. atroviolacea, were investigated by optical microscopy. The relative crystallinity and crystalline width of the culm of the bamboo species were examined by an X-ray diffraction method. These species contained vascular bundle of type III. Vascular bundle density was higher in the outer part of bamboo culm than in the inner. Fiber portion decreased from the outer part to the inner part and vice versa for the parenchyma and vessel portions. Fiber length of all species was higher in the outer part than the inner part of the culm. There was a significant difference in the fiber percentage between the bamboo species. Significant differences were also found in vessel diameter and parenchyma cell dimensions among the bamboo species. There was a slight difference in the crystalline properties between the outer and inner parts of the culm and among the bamboo species. All parameters showed a variation in the radial direction of the three bamboo culm but did not show a consistent tendency along the vertical direction.