STUDY ON WOOD ANATOMY AND MECHANICAL PROPERTIES OF CLONE RRIM 3001 WITH PROTUBERANCES
Protuberance formation on clone RRIM 3001 has created an anxiety among many rubber forest plantation investors in Malaysia. Protuberance formation on tree trunk could potentially affect wood quality produced from rubber forest plantations. Hence, return on investment at the end of every plantation cycle will below. Clone RRIM 3001 has been recorded to have a high bole volume. It is also one of the high yielding rubber clones available and thus it is popular among rubber forest plantation investors. This study focused on the anatomy and mechanical properties of wood produced from clone RRIM 3001 and the location of the protuberance on the trunk was assigned as a reference point for each layer of plank used for the mechanical test carried out. A total of four locations in Malaysian Rubber Board’s Experimental Station in Kota Tinggi, Johor were selected as experimental sites in this study. Rubber trees of clone RRIM 3001 at ages 5, 10, 15 and 20 years from field 109 and 113 of Pelepah, Penawar and Pemandi divisions respectively, were selected as experimental units in this study. Data collected from this study showed that the range at which the protuberances could be found on the trunk of RRIM 3001 was between 133 cm and 1026 cm from the ground. Presence of protuberance was higher at the lower part of trunk and became consistently few in terms of density at above the height of 500 cm from the ground. The protuberance orientation was in two directions, either vertical or horizontal to the tree trunk. There was a significant bark thickness difference in the area with protuberance (9.6 mm) from those without (9.0 mm). Cell formation within the area with protuberance had shown a unique characteristic and was scattered. Smaller cells were observed inside the vessel cells on the protuberance area. However, there was no significant difference with regard to size of vessel cell between areas with and without protuberance. The mechanical properties of the wood from the samples collected were not significantly different between the areas with and without protuberance. It could be suggested that the unique characteristic of cell development and formation in the vessel cell are the defence response of clone RRIM 3001 in order to strengthen damaged areas on the tree trunk. The results of this study have given an indication that the protuberance formation on the tree trunk of clone RRIM 3001 has no adverse effect on wood quality.
Keywords: shear, hardness, compression, modulus of elasticity, modulus of rupture