VERTICAL AND RADIAL VARIATION OF NUCLEAR ELONGATION INDEX OF LIVING SAPWOOD RAY PARENCHYMA CELLS IN A PLANTATION TREE OF CRYPTOMERIA-JAPONICA

Vertical and radial variations of nuclear elongation index (NEI) of li ving sapwood ray parenchyma cells were studied in a 45-year-old planta tion tree of Cryptomeria japonica D. Don collected in Taiwan on Februa ry 27, 1992. Nine wood strips oriented in an E-W direction of the tree were collected starting at 0.3 m above ground level, and progressing upwards by 2.5 m intervals to the tree crown. Radial sections, 20 mum thick, were cut from the cambium toward the inner sapwood of these nin e wood strips. The nuclear elongation index (NEI) was used to express the metabolic activity of the ray cells. It was found that metabolic a ctivity of sapwood ray parenchyma was the highest at the outer sapwood and declined gradually towards the inner sapwood. The lowest average NEI was found at the lowest stem level. The average NEI of various ste m height levels increased with increasing stem height level. The avera ge NEI of three growth rings at the outer sapwood near the cambium rea ched a maximum at the bottom of the live crown.