Estimation of Genetic Parameters and Wood Yield Selection Index in a Clonal Trial of Korean Pine (Pinus koraiensis) in Northeastern China

In order to determine suitable traits for selecting high-wood-yield Korean pine materials, eleven morphological characteristics (tree height, basal diameter, diameter at breast height, diameter at 3 meter height, stem straightness degree, crown breadth, crown height, branch angle, branch number per node, bark thickness, and stem volume) were investigated in a 38-year-old Korean pine clonal trial at Naozhi orchard. A statistical approach combining variance and regression analysis was used to extract appropriate traits for selecting elite clones. Results of variance analysis showed significant difference in variance sources in most of the traits, except for the stem straightness degree, which had a p-value of 0.94. Moderate to high coefficients of variation and clonal repeatability ranged from 10.73% to 35.45% and from 0.06% to 0.78%, respectively. Strong significant correlations on the phenotypic and genotypic levels were observed between the straightness traits and tree volume, but crown breadth was weakly correlated to the volume. Four principal components retaining up to 80% of the total variation were extracted, and stem volume, basal diameter, diameter at breast height, diameter at 3 meter height, tree height, and crown height displayed high correlation to these components (r ranged from 0.76 to 0.98). Based on the Type III sum of squares, tree height, diameter at breast height, and branch number showed significant information to explain the clonal variability based on stem volume. Using the extracted characteristics as the selection index, six clones (PK105, PK59, PK104, PK36, PK28, and K101) displayed the highest Qi values, with a selection rate of 5% corresponding to the genetic gain of 42.96% in stem volume. This study provides beneficial information for the selection of multiple traits for genetically improved genotypes of Korean pine.

Adjusting for the effect of missing or dominated plants in progeny and clonal trials of Eucalyptus

The objective of this paper was to estimate the effect of either missing or dominated plants (those that developed poorly) in experiments evaluating progenies or clones of Eucalyptus. Additionally, it was to investigate whether the use of the area available per plant is a suitable strategy to mitigate the effect of missing plants. Lastly, it was to evaluate whether missing or dominated plants in the experiments affected the association between plant performance in a progeny trial (PT) and their respective clones in a clonal trial (CT). Five 5-year-old PTs and four 3-year-old CTs were used. The recorded trait was diameter at breast height (DBH). The area available per plant was used to carry out the adjustment, taking into consideration the absence of neighboring plants as well as dominated plants. It was found that with the level of missing plants below 20% in experiments, the adjustment using the area available per plant did not improve the efficiency of the selection of either PTs or CTs. The strategy of considering not only missing plants but also dominated plants is not beneficial for the adjustment.

Modeling of basic density of wood from Eucalyptus grandis and Eucalyptus urophylla using nondestructive methods

The objective of this study was to evaluate the accuracy of nondestructive variables in inferring basic density of wood from Eucalyptus grandis and Eucalyptus urophylla. A total of 27 clones of Eucalyptus urophylla and 22 clones of Eucalyptus grandis were used, sourced from a clonal trial set up in Martinho Campos, Minas Gerais. After evaluation using nondestructive techniques of resistography and pin penetration at a constant pressure (Pilodyn®), individuals were felled and disks were removed from the 2%, 10%, 30%, 50% and 70% portions of the merchantable height section, and also from the portion 1.30 m above ground level. Basic density was determined by the water immersion method. Values of basic density ranged from 0.412 to 0.609 g.cm-3 for clones at age 42 months and from 0.408 to 0.664 g.cm-3 for clones at age 54 months. The clones of Eucalyptus urophylla provided higher values of average basic density in relation to Eucalyptus grandis. The variable 'amplitude' had better correlation with basic density in comparison with pin penetration at a constant pressure. Nondestructive evaluation can be used in mass preselection of genetic materials, prior to subjecting them to a more accurate, reliable evaluation.

Competition Effects in a Young Sitka Spruce (Picea sitchensis, Bong. Carr) Clonal Trial

In the analysis of forestry experiments, there may be a need to adjust for competition between plots before predicting deployment performance in the field but there have been few attempts to investigate this. Our analysis looked at diameter data from a 19-year old Sitka spruce clonal trial growing in Scotland. Using a sequence of nested models, a likelihood ratio test indicated that fitting competition at both the genetic and residual level provided a significantly better fit than models which either ignored competition or fitted it at just the genetic or just the residual level. A strong negative genetic correlation of −0.93±0.05 was found between the direct genetic effects and competition effects. This was not significantly different from −1, indicating that competition is almost exactly proportional to the direct genetic effect and that a tree will exert a competitive effect which is closely related to its own genetic merit for size. At the residual level, the correlation between direct and competition effect was estimated as −0.17±0.03. We conclude that competition exists at both the genetic and environmental levels and including it in genetic evaluation systems gives a better prediction of future performance. Results also demonstrate that it is possible to obtain useful information about competition effects from a single-tree plot experiment.

First evaluation of growth parameters in clonal test with wild cherry

A 6-year-old clonal trial with 13 clones of wild cherry (<i>Prunus avium</i> L.) was evaluated during the summer of 2004 at 6 different sites in the Czech Republic. Observed traits were the stem height, stem diameter, health status, and mortality. The mixed linear model was implemented with either independent or the autoregressive error structure. The later provided better fit to the data. At this age, only one clone outperformed the remaining ones in volume production. Suggestions for future research activities are provided that should lead to the establishment of long-term breeding programs with wild cherry in the Czech Republic.

Spiral grain in a clonal trial with Sitka spruce

Grain angles to the left in seven clones of Sitka spruce (Picea sitchensis (Bong.) Carr.) decreased from the pith and outwards and with height. Effects of compression wood and compass directions were non-significant. Clones differed significantly but interacted with height levels, ring numbers, compass direction, and compression wood. However, the interaction with compression wood was small. Furthermore, some interaction with compass direction could possibly be attributed to eccentric stems and stem axis choice. The repeatability was 72% for averages of ramets measured in five height levels and most rings from the pith. The mean spiral grain was 2.2°, and the phenotypic standard deviation between averages of ramets was 1.07°. Genetic gains of 1° from phenotypic selections based on several measurements were suggested using these values. Variations between ramets and residual variances accounted for most of the variation. Thus, as many ramets as possible should be sampled to obtain the best estimates of mean clonal levels. Clone interactions with height levels and ring numbers from the pith were less important. This was also explained by correlations of 0.83–0.98 among clone averages at 1.3 m for single rings and overall clone means. Only significant effects ring widths were present within clones.