Estimates of genetic and environmental variances and heritabilities for natural populations of Virginia pine (Pinus virginianas Mill.)

The study was undertaken to determine the genetic and environmental variance and narrow sense heritability for the natural population of Virginia pine (Pinus virginiana Mill.) in Kentucky and Tennessee. Open pollinated progeny from 3 to 13 families each of 13 natural stands were planted in 10 tree row plots at 6 test locations to furnish the test data. An IBM program was developed to perform an analysis of variance and estimate components of variance. Characteristics analyzed were first year height and second year height, branch length, branch diameter, and stem diameter. Each site was analyzed separately. There was a significant difference in second year height and stem diameter among stands at all test sites. In second year stand mean heights at all test sites, stands from the Great Valley physiographic source tended to rank higher than the other physiographic sources. Variance components values were highly variable among test sites and fluctuated positively with the mean values of each site. Variance components were relatively the same size at each test site for each of the second year characteristic measured because of the close positive correlation among these characteristics. Heritability of first year height and second year height, branch length, branch diameter, and stem diameter averaged 0.28, 0.28, 0.21, 0.16, and 0.20, respectively, among all test sites. The highest heritability value (0.48) was for second year height at the Highland Rim test site. It was estimated that a genetic gain of 25 percent could be made by the selection of the best 45 individual of the best 45 families of the best seven stands at the Highland Rim test site. If stand selection was not practiced, a gain of 21 percent was estimated. Gain from mass selection was estimated to be only 5 percent.