GENETIC PARAMETER ESTIMATES FOR WOOD DENSITY, TRANSITION AGE, AND RADIAL GROWTH IN SLASH PINE

Genetic parameters for wood density and wood density components of slash pine (Pinus elliottii Engelm.) were estimated using measurements on 56 open-pollinated families. Increment cores were taken at breast height from six trees per family on each of two sites and density profiles generated using X-ray densitometry. There was no practical genetic variance for earlywood density; however, ring density, latewood density, latewood percentage, and transition ages for those traits were all heritable. Moderate selection pressure (selection of top 25%) on transition age would be expected to decrease transition age by approximately 1 year, but this would likely cause a correlated increase in the density of juvenile wood, and decrease in the density of mature wood. Selection for increased mature wood density and juvenile wood density will likely increase whole tree density by 0.02 g/cm3.