Genetic variation for growth, wood and fibre properties of Pinus patula families grown on six sites in South Africa.
Date
2007-03
Authors
Vermaak, J. A.
Journal Title
Journal ISSN
Volume Title
Publisher
Stellenbosch : University of Stellenbosch
Abstract
This study evaluates the variation that exists between six sites and between more than
200 Pinus patula families established across the sites for various traits utilised in a tree
improvement programme. The traits utilised were growth at ages five and eight years,
gravimetric densitometry of a sub-sample of the top 100 families at age eight, and microdensitometry
and fibre morphological characteristics as determined by image analysis of
increment cores, extracted from a sub-sample of the top 30 families. Significant
differences were found between locations for growth at ages five and eight, density (both
gravimetric and micro densitometry) and fibre properties. For each of the site
combinations, utilising Type B- genetic correlations, the interaction between families and
locations were evaluated in order to determine which locations could be grouped together
in order to determine the effect various sites will have on the deployment of material.
Significant differences were also found between families for the various traits
investigated, which would indicate that desired trait or trait combinations can be selected
for in a tree improvement programme. Heritability estimates for growth varied across
sites, ranging from 0,32 to 0,57 at five years and 0,34 to 0,59 at eight years for family
heritability. The individual tree estimates ranges from 0,08 to 0,27 at five years and from
0,09 to 0,26 at eight years. The standard errors associated with the heritability estimates
for growth however indicate that the estimates, especially those of the individual trees
should be used with caution. The heritability estimates for density and fibre
morphological characteristics on the family and individual tree level are on a number of
sites very high, although this is associated with large standard errors. Indications were
that the traits can be combined effectively into a multi-trait selection index, since the
phenotypic and genotypic correlations indicated mostly favorable or slight negative
correlations between traits.
Description
Thesis (MScFor (Forest and Wood Science))--University of Stellenbosch, 2007.
Keywords
Dissertations -- Forest and wood science, Theses -- Forest and wood science, Pinus patula -- Variation -- South Africa, Pinus patula -- South AfricaGenetics, Pinus patula -- Breeding -- South Africa