Seasonal Changes of Wood Formation and some Characteristics of Heartwood Formation in Teak (Tectona grandis L.) Plantation

Abstract

Some fundamental investigations of wood and heartwood in plantation grown teak (Tectona grandis L.) were carried out. In order to verify the relationship between wood formation and growing conditions, moisture content of soil and the development of leaves were also studied. It was found that moisture content of soil was higher in the rainy season. Since trees started budding in May which was the beginning of the rainy season, those trees grown at the foot of the hill showed earlier development of leaves. As for the time sequence of wood formation using the pining method, it was revealed that wood formation started after the budding and continued to do so until the end of rainy season. Parenchyma cells of the outer sapwood had great amount of starch grains as reserve substances and this amount abruptly decreased in the middle and inner part of sapwood. Parallel with the decrease of starch grain, lipid droplets increased. However, in the heartwood, both parenchyma cell and wood fibers contained lipid droplets. Elemental analysis of the black substance in the outer heartwood was tried by SEM-EDXA method and it was revealed that no special element was contributed to the black streak of heartwood.