Annual Rhythm of Xylem Growth in Rubberwood (Hevea brasiliensis) Trees Grown in Malaysia

Abstract

Summary The periodicity of the growth increment in six rubber wood (Hevea brasiliensis Muell. Arg.) trees grown in Peninsula Malaysia was investigated continuously throughout three years using the pinning and the band-dendrometer method. The pinning and dendrometer data were analyzed for obtaining the correlation with the seasonal rhythm of radial growth and circumferential increments. The data of growth increments measured with the dendrometer continuously for three years indicated growth dormancy during the first three to five months (from January to March or May) each year in all the sample trees, in which annual ring-like features were observed. This means that rubber wood trees have an annual rhythm in the xylem growth. The boundary zone consisted of flattened wood fibers with thin walls, axial parenchyma cells, and small vessels. On the other hand, those obtained from the pinning method showed a vague growth dormancy around March every year. It seemed that growth measurement in tropical trees using the dendrometer is useful for detecting the growth rhythm of cambium.