VARIASI GENETIK SIFAT FISIKA KAYU Pinus merkusii Jungh. et de Vriese

R. Gatot Nursinggih Harjanto, Prof.Dr.Ir. Hj. Oemi H.S

1996 | Tesis | S2 Ilmu Kehutanan

Elevens years old Ptnus merkusti trees from half-slb progeny test were sampled for study specific gravity, moisture content, shrinkage, bole straightness, branching type and circumference. Sample disks removed from 225 trees at 200 cm above ground during thinning. Analysis of variance indicated significant differences among trees for specif le gravity, air-dry moisture content and bole straightness. Variation of wood within trees from pi th to bark also occurred. Significant differences within trees variation was· detected for specific gravity, green moisture content and shrink­age. Average over all trees for its specific gravity , radial shrinkage and tangential shrink age increased across disk from pl th outwards, but the results shows an opposite tendency for green moisture content and longitudinal shrinkage.

Elevens years old Ptnus merkusti trees from half-slb progeny test were sampled for study specific gravity, moisture content, shrinkage, bole straightness, branching type and circumference. Sample disks removed from 225 trees at 200 cm above ground during thinning. Analysis of variance indicated significant differences among trees for specif le gravity, air-dry moisture content and bole straightness. Variation of wood within trees from pi th to bark also occurred. Significant differences within trees variation was· detected for specific gravity, green moisture content and shrinkage. Average over all trees for its specific gravity , radial shrinkage and tangential shrink age increased across disk from pl th outwards, but the results shows an opposite tendency for green moisture content and longitudinal shrinkage. Estimates of heritability were high for specific gravity (h2i = 0.571), air-dry moisture content (h2 i = 0.634, bole straightness (h2i = 0.522), but moderate for green moisture content. Heritabllities for middle wood and outer wood were high. Therefore, there ls an opportunity to improve the quality of wood by decreasing the proportion of juvenile wood through trees selection. Genetic correlations among several traits indicate significant differences, except for both bole straightness and green moisture content. Phenotypic correlation indicate significant differences only between traits specific gravity and green moisture content because environment effect acting on these traits are negatively correlated. While increasing specific gravity, it is possible to decrease its green moisture content but it seems difficult to increase specific gravity and bole straightness simultaneously . Furthermore, genetic gains using indirect selection for several traits were low, except for spec l f le gravity and green moisture content with the relative selection efficiency -0.540 and -1.109, respectively. Selection index ls the best way to achieve improvement if the two traits could not be improve simultaneously. Genetic gains using selection index were low with relative selection efficiency ranged from 0.01 to 0.27.

Kata Kunci : Ilmu Kehutanan,Kayu Pinus Merkusii Jungh et de Vriese