GROWTH CHARACTERISTICS OF EUCALYPTUS CAMALDULENSIS DEHN.H. CLONES

บทคัดย่อ

Clonal test plots of Eucalyptus camaldulensis were made at FIO Sakaew Plantation, Wang Namyen district, Sakaew province. Nine-teen which included seventeen clones produced through tissue culture technique and two groups of trees originated from seeds, imported seeds by Shell and locally collected seeds, were compared. Annual growth, diameter at breast height (dbh) and total height (Ht) were measured until 5 years. Total height, merchantable height (Hm), Hm/Ht, stem taper, wood and bark characteristics of 5 year-old trees were investigated from the cut sample trees and compared. Total height and dbh for all trees were rapidly increase from age 1 to 2 years which the maximum growth at 7.50 m/yr for height and 7.56 cm/yr for dbh, then the growth were abruptly decline from age 3 to 5 years. Growth characteristics; dbh, Ht, Hm, Hm/Ht and taper of stems were significantly different between clones and trees originated from seeds. Based on dbh, 3 groups of the experimental trees were classified as follows: fast growing (>16 cm), moderate growing (14-16 cm) and slow growing (<14 cm). Five clones (K2, T5, S9, Y2 and Kitti) were considered as fast growing group which dbh were 16.88-18.43 cm. Trees originated from seeds. Shell and local seeds, were in slow dbh growing group which dbh were 13.72 cm and 13.10 cm, respectively. Total tree heights were mainly coincident with dbh, the clones in fast dbh growing group showed the highest height ranged from 17.86 to 20.40 m. The average height of trees from the local seeds was 16.61 m while those of the trees from Shell seed source was 18.23 m which was as high as the tree in the fast growing group. Hm and Hm/Ht were highly correlated to Ht (r = 0.9788), but less correlated to dbh (r = 0.5732). Stem taper was significantly different between clones but did not correlate to the dbh and height growth groups. Bark thickness and moisture content did not correlate to the size and the growth rate of trees, they were specific characteristics for each individual.