Doctoral Dissertations

Date of Award

3-1987

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Ecology and Evolutionary Biology

Major Professor

Edward R. Buckner

Committee Members

James B. McLaren, Robert A. McLean, William L Parks, John C. Rennie

Abstract

Third-year data from half-sib progeny tests of Virginia pine located in north Alabama and central Tennessee were evaluated to deter mine the genetic and environmental sources of variation for characteristics potentially important to the production of quality Christmas trees. Each progeny test was composed of 20 families from the Kimberly-Clark Corporation seed orchard and 36 families from a previously established plantation at the Highland Rim Forestry Field Station, Tennessee.

No major differences were found between the two seed sources and the source x location and family-within-source x location interaction terms were not significant. Families from either source may be utilized as seed sources for either location. Estimates of heritabilities for each location are given. Based on these estimates and the relative contribution of each characteristic to the overall quality of a Christmas tree, height, branches per whorl, color, crook and rating were selected to evaluate trees to be included in a breeding program. Genetic gains are presented, resulting in an increase in height of 12 cm at age three and a 5 percent reduction in the number of cull trees.

To determine if any characteristics pertaining to seed, seedlings, first-year field performance or second-year field performance can be used to predict third-year performance, eight seeds were selected from each of 57 half-sib families of Virginia pine. Each seed was measured, planted and subsequently remeasured as a seedling. The seedlings were field-planted and measured annually. The two test planntations utilized to determine heritabilities were also measured annually. The linear relationship of each set of measurements to the next set was determined by use of canonical correlations.

Seed, seedling and first-year field measurements were not accurate predictors of third-year field performance. Second-year measurements had canonical correlations ranging from 0.85 to 0.90 with third-year measurements and explained between 58 and 71 percent of the variance in the third-year measurements. Only the first canonical variate explained more than 2 percent of the third-year variation. The primary components of the first canonical variate were height and diameter which can be used to cull up to 66 percent of the trees without reducing the number of select trees.

Download
Files over 3MB may be slow to open. For best results, right-click and select "save as..."

Share

COinS