Abstract: This paper studies the genetic variation of wood qualitios among I-69 (Populus deltoides Bartr. cl. "Lux" (I-69/55) )and 14 clones of Hybridization combination No. 34-I-69×I-63 (P. deltoides Bartr. cl. "Harvard" (I-63/51)) . Increment cores with diameter of 0.5cm, from eastern direction at DBH, were collected from one single tree for each of 15 clones from each of three blocks.The Results showed that the difference of specific gravity among clones was signicant at 5% of probadility level. The specific gravity of I-69 is significantly higher than that of any clone in combination No.34.However,no significant difference was found among 15 clones for fiber length, fiber width and fiber length/width ratio. The estimated value of broad-sesnse heritability (h²) for specific gravity, fiber length, fiber width and fiber length/width ratio, were 0.7, 0.12, 0.33 and 0.15, respectively. In addition, no significant correlation was found between the growth traits and wood qualitios. It is possible for some fast-growing clones to have good wood qualitios.

Key words: Populus deltoides, Specific gravity, Fiber characteristics, Genetic vriation