|Authors: ||S. Pojanagaroon, C. Kaewrak|
|Keywords: ||Kritsana tree, Aquilaria crassna, aloes wood, oleoresin deposition|
Various mechanical injury methods were tested to induce formation of aloes wood in 4-year-old Aquilaria crassna Pierre ex H.Lec. (kritsana) trees grown at Phurua Highland Agricultural Experiment Station, Phurua, Loei (950 m asl, 17°17’N 101°24’E) during February 2001 to October 2002. A sequential change in the wood coloration was observed around injury sites.
One month after wounding a pale discoloration occurred, followed by a darker yellow-brown discoloration after 3 months, becoming dark brown within 8-10 months and changing to black within 20 months with accompanied on burning scent.
Wood block samples collected from live tree at 10, 15 and 20 months after wounding were compared among the different mechanical treatments.
The results indicated that holes made with screws, wounds inflicted with chisels and bark removal with hatchets on the trunk gave dark yellow-brown to dark discoloration near injury (5-10 mm from the cut end), while nails hammered into the trunk gave dark brown to black occurring by the interaction between ferric oxide and fibers, where as hammers beated on the trunk gave only little discoloration.
The larger the objects used to wound the trunk of kritsana trees, the wider the width of the discoloration ring.
The rate of the formation of the discoloration ring around the wound in the rainy season (16-20 months after wounding) was 3 times higher than in the dry season (11-15 months after wounding), influenced by seasonal factors.
Most treatments gave no specific aromatic kritsana scent by burning the wood samples, except only 4 treatments gave pale scent which were the holes made with screws (1.27 cm and 1.11 cm in diameter) and wounds inflicted with narrow (1 cm) and wide (2.54 cm) chisels.
Moreover, the wood samples gave very low percentage yields of essential oil using a hydro-distillation method.
In conclusion, mechanical injury can be used for the formation of aloes wood in kritsana trees, and the most suitable method was the holes made with screws (1.27 cm in diameter) which gave the widest discoloration ring and pale specific aromatic kritsana scent by burning.
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