ANALYSIS OF EUCALYPTUS'S HYBRIDS USING MORPHOLOGICAL AND GROWTH CHARACTERISTICS

Abstract

The intraspecific hybrids of Eucalyptus camaldulensis and the interspecific hybrids of E. camaldulensis x E. urophylla, E. camaldulensis x E. tereticornis and E. camaldulensis x E. citriodora were selected for this study. 290 clones prepared from 29 selected breeding families were planted to test for field performance at Klong-Takrao plantation of Forest Industry Organization (FIO), Chachengsao province. Leaf morphology, dbh, height and healthy levels (discase damage levels) were gathered when the trees were one-year old. Leaf shape was a morphological characteristic enabling to confirm the interspecific hybrids of E. camaldulensis x E. urophylla because their leaf shapes were similar to those of E. urophylla but could not confirm other crosses. Symtoms of disease was generally found on the experimental trees and was more severe while rain being heavy and continuous. The severity of disease damage trees depended on the types of hybrids. The interspecific hybrids showed less damage and more healthy. However the less resistant parents produced hybrids with more severe damage which implied that disease resistance characteristics were inheritance. The growth rate of the hybrids depended on parents. The hybrids of clone T5 x E. urophylla produced the hybrids with more disease resistance, greatest growth, of which their average dbh and height were 3.38 cm. and 4.22 m. respectively. Therefore the interspecific crossing provided a possibility to obtain good hybrids viz more disease resistance and better growth.