scholarly journals The Effects of Drying Temperature and Method of Assessment on the Expression of Genetic Variation in Gross Shrinkage of Eucalyptus globulus Wood Samples

2009 ◽  
Vol 58 (1-6) ◽  
pp. 252-261 ◽  
Author(s):  
Matthew G. Hamilton ◽  
C. E. Harwood ◽  
B. M. Potts
Keyword(s):  
Genetic Variation ◽  
Eucalyptus Globulus ◽  
Genetic Correlations ◽  
Basic Density ◽  
Strongly Correlated ◽  
Drying Temperature ◽  
Additive Genetic Variation ◽  
Tangential Shrinkage ◽  
Drying Treatment ◽  
Method Of Assessment

Abstract Genetic variation in wood-sample gross shrinkage and basic density was examined in a Eucalyptus globulus base population trial growing in Tasmania, Australia. Gross shrinkage, which includes all components of shrinkage including collapse, was assessed in four ways (calliper- and visually-assessed tangential shrinkage, volumetric shrinkage and radial shrinkage) on samples dried at three temperatures (22°C, 60°C and 105°C). Significant differences between subraces were observed using all measures of gross shrinkage for two or more of the three drying treatments. Furthermore, significant additive genetic variation within subraces was observed in calliper- and visually-assessed gross shrinkage under two or more of the drying treatments, with narrowsense heritabilities greater than or equal to 0.35. There was no obvious trend in heritabilities or coefficients of additive genetic variation with drying temperature. Under the 105°C drying treatment, subrace correlations among calliper-, visually- and volume-assessed gross shrinkage were positive and very strong (≥ 0.97), while these measures were less strongly correlated with radial gross shrinkage at the subrace level (≤ 0.77). Withinsubrace genetic correlations among the first three measures were also strongly positive (≥ 0.95). These high genetic correlations suggest that different drying regimes and the calliper, visual and volume methods of assessment could be used interchangeably to select for reduced tangential gross shrinkage. Estimated subrace and genetic correlations between basic density and measures of gross shrinkage were universally negative (i.e. favourable), although not all were significantly different to zero.

scholarly journals Genetic Variation of Physical and Chemical Wood Properties of Eucalyptus globulus

2005 ◽  
Vol 54 (1-6) ◽  
pp. 160-166 ◽  
Author(s):  
L. A. Apiolaza ◽  
C. A. Raymond ◽  
B. J. Yeo
Keyword(s):  
Genetic Variation ◽  
Eucalyptus Globulus ◽  
Genetic Correlations ◽  
Fibre Length ◽  
Microfibril Angle ◽  
Basic Density ◽  
Wood Properties ◽  
Pulp Yield ◽  
Cellulose Content ◽  
Wood Processing

Abstract This study considered the degree of genetic variation for diameter (DBH), basic density (BD), predicted pulp yield (PPY), fibre length (FL), microfibril angle (MFA) and cellulose content (CC) amongst eight subraces of Eucalyptus globulus growing in a field trial in NW Tasmania. There were significant subrace effects for BD, FL and CC. This variation affected the relative profitability of the subraces for pulp production. On average, the most profitable subraces (on NPV/ha over the base population mean) were Strzelecki Ranges ($862.04), Western Otways ($657.80) and Strzelecki Foothills ($576.81). The genetic control (heritability) of variation in DBH, FL and MFA was moderate (0.15 < h2< 0.27), while control for BD, PPY and CC was high (h2> 0.40). Genetic correlations between growth and wood properties were not statistically significant, except for DBHMFA (-0.86). Most genetic correlations amongst wood properties were outside the parametric space (< -1 or >1), but there were significant correlations between BDMFA (-0.70) and PPY-CC (0.82). The empirical response to selection on an index based on a pulp wood objective (which included volume and basic density) resulted in a gain of 4.3% for DBH, 7.9% for BD and marginal changes for all other traits, with a net impact in profit of $1,270/ha. However, future profit calculations will need to consider the effect of FL, MFA and CC on the economics of wood processing to fully evaluate the economic impact of breeding.

Genetic control of kraft pulp yield in Eucalyptus globulus

2010 ◽  
Vol 40 (5) ◽  
pp. 917-927 ◽  
Author(s):  
Desmond J. Stackpole ◽  
René E. Vaillancourt ◽  
Geoffrey M. Downes ◽  
Christopher E. Harwood ◽  
Brad M. Potts
Keyword(s):  
Genetic Control ◽  
Eucalyptus Globulus ◽  
Kraft Pulp ◽  
Near Infrared ◽  
Genetic Correlations ◽  
Basic Density ◽  
Pulp Yield ◽  
Narrow Sense Heritability ◽  
Selection Gradients ◽  
Economic Worth

Pulp yield is an important breeding objective for Eucalyptus globulus Labill., but evaluation of its genetic control and genetic correlations with other traits has been limited by its high assessment cost. We used near infrared spectroscopy to study genetic variation in pulp yield and other traits in a 16-year-old E. globulus trial. Pulp yield was predicted for 2165 trees from 467 open-pollinated families from 17 geographic subraces. Significant differences between subraces and between families within subraces were detected for all traits. The high pulp yield of southern Tasmanian subraces suggested that their economic worth was previously underestimated. The narrow-sense heritability of pulp yield was medium (0.40). The significant positive genetic correlation between pulp yield and diameter (0.52) was at odds with the generally neutral values reported. The average of the reported genetic correlations between pulp yield and basic density (0.50) was also at odds with our nonsignificant estimate. Pulp yield of the subraces increased with increasing latitude, producing a negative correlation with density (–0.58). The absence of genetic correlations within subraces between pulp yield and density suggests that the correlation may be an independent response of the two traits to the same or different selection gradients that vary with latitude.

The genetic variation in the timing of heteroblastic transition in Eucalyptus globulus is stable across environments

2011 ◽  
Vol 59 (2) ◽  
pp. 170 ◽  
Author(s):  
M. G. Hamilton ◽  
P. A. Tilyard ◽  
D. R. Williams ◽  
R. E. Vaillancourt ◽  
T. J. Wardlaw ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Phase Change ◽  
Eucalyptus Globulus ◽  
Developmental Change ◽  
Genetic Correlations ◽  
Genotype By Environment Interaction ◽  
Environment Interaction ◽  
Narrow Sense Heritability ◽  
Genotype By Environment ◽  
Analyse Data

Eucalyptus globulus is one of the best known examples of a heteroblastic plant. It exhibits a dramatic phase change from distinctive juvenile to adult leaves, but the timing of this transition varies markedly. We examined the genetic variation in the timing of heteroblastic transition using five large open-pollinated progeny trials established in north-western Tasmania. We used univariate and multi-variate mixed models to analyse data on the presence/absence of adult or intermediate foliage at age 2 years from a total of 14 860 trees across five trials, as well as height to heteroblastic phase change from one trial. Up to 566 families and 15 geographic subraces of E. globulus were represented in the trials. The timing of the heteroblastic transition was genetically variable and under strong genetic control at the subrace and within-subrace level, with single-trial narrow-sense heritability estimates for the binary trait averaging 0.50 (range 0.44–0.65). The degree of quantitative trait differentiation in the timing of heteroblastic transition among subraces, as measured by QST, exceeded the published level of neutral molecular marker (FST) differentiation in all cases, arguing that diversifying selection has contributed to shaping broad-scale patterns of genetic differentiation. Most inter-trial genetic correlations were close to one at the subrace and additive genetic levels, indicating that the genetic variation in this important developmental change is expressed in a stable manner and that genotype-by-environment interaction is minimal across the environments studied.

Development of near infrared reflectance analysis calibrations for estimating genetic parameters for cellulose content in Eucalyptus globulus

2002 ◽  
Vol 32 (1) ◽  
pp. 170-176 ◽  
Author(s):  
C A Raymond ◽  
L R Schimleck
Keyword(s):  
Eucalyptus Globulus ◽  
Kraft Pulp ◽  
Near Infrared ◽  
Genetic Correlations ◽  
Basic Density ◽  
Pulp Yield ◽  
Cellulose Content ◽  
Infrared Reflectance ◽  
Near Infrared Reflectance ◽  
Reflectance Analysis

Determining kraft pulp yield in the traditional way is slow and expensive, limiting the numbers of samples that may be processed. An alternative is to use a secondary standard, such as cellulose content of the wood, which is strongly correlated with kraft pulp yield. The feasibility and efficiency of predicting cellulose content using near infrared reflectance (NIR) analysis was examined for Eucalyptus globulus Labill. Calibrations for NIR prediction of cellulose content indicated that NIR analysis could be used as a reliable predictor. Standard errors of calibration were 1% or lower, and there was excellent agreement between laboratory and predicted cellulose values. Cellulose content was under moderate genetic control (h2 ranging from 0.32 to 0.57), and genetic correlations with tree diameter and basic density were variable (ranging from –0.11 to –0.51 and –0.33 to 0.67, respectively). The advantages, disadvantages, and potential applications of NIR analysis for predicting cellulose content are examined.

Genetic control of Eucalyptus globulus harvest traits

2015 ◽  
Vol 45 (6) ◽  
pp. 615-624 ◽  
Author(s):  
Matthew G. Hamilton ◽  
Mauricio Acuna ◽  
John C. Wiedemann ◽  
Rick Mitchell ◽  
David J. Pilbeam ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Eucalyptus Globulus ◽  
Genetic Correlations ◽  
Basal Area ◽  
Field Trials ◽  
Slight Reduction ◽  
Growth And Survival ◽  
Short Rotation ◽  
Stem Straightness ◽  
Tree Genetics

The cost of harvesting short-rotation plantation eucalypts can be in excess of AU$2500·ha−1. Despite this high cost, the extent to which harvesting productivity is affected by tree genetics is not well understood. We address this issue in a study of two 10-year-old genetic field trials of Eucalyptus globulus Labill. in Australia. Standing-tree traits analysed were survival, diameter at breast height, basal area, and stem straightness and forking. Harvest traits analysed were volume, time, and productivity. Genetic group and within-group genetic variation (additive and dominance), stand-level family variation, phenotypic and genetic correlations, and the effects of inbreeding were estimated for these traits. The different scenarios studied showed that plantation harvest productivity was affected by tree genetics to some degree but was mainly affected through positive covariation with stem diameter. Harvest productivity is thus unlikely to have been adversely affected by past selection. Although no significant additive or dominance genetic variation in stem forking or straightness was detected, weak phenotypic correlations were consistent with harvest productivity being higher in straighter trees with no forking. High inbreeding depression was evident for growth and survival; however, in open-pollinated progeny, this resulted in only a slight reduction in harvest productivity (5.5%) compared with out-crossed progeny.

Genetic variation for resistance to clinical and subclinical diseases exists in growing pigs

2001 ◽  
Vol 73 (3) ◽  
pp. 375-387 ◽  
Author(s):  
M. Henryon ◽  
P. Berg ◽  
J. Jensen ◽  
S. Andersen
Keyword(s):  
Genetic Variation ◽  
Respiratory Diseases ◽  
Additive Genetic Variance ◽  
Genetic Correlations ◽  
Frailty Model ◽  
Growing Pigs ◽  
Disease Category ◽  
Breeding Values ◽  
Additive Genetic Variation ◽  
Subclinical Disease

AbstractThe objective of this study was to test that genetic variation for resistance to clinical and subclinical diseases exists in growing pigs. A total of 13 551 male growing pigs were assessed for resistance to five categories of clinical and subclinical disease: (i) any clinical or subclinical disease, (ii) lameness, (iii) respiratory diseases, (iv) diarrhoea, and (v) other diseases (i.e. any clinical or subclinical disease with the exception of (ii), (iii), and (iv)). Additive genetic variation for resistance to each disease category was estimated by fitting a Weibull, sire-dam frailty model to time until the pigs were first diagnosed with a disease from that category. Genetic correlations among the resistances to each disease category were approximated as product-moment correlations among predicted breeding values of the sires. Additive genetic variation was detected for resistance to (i) any clinical or subclinical disease (additive genetic variance for log-frailty (± s.e.) = 0·18 ± 0·05, heritability on the logarithmic-time scale = 0·10), (ii) lameness (0·29 ± 0·11, 0·16), (iii) respiratory diseases (0·24 ± 0·16, 0·12), (iv) diarrhoea (0·30 ± 0·27, 0·16), and (v) the other diseases (0·34 ± 0·15, 0·19) and there were generally positive and low-to-moderate correlations among the predicted breeding values (-0·03 to + 0·65). These results demonstrate that additive genetic variation for resistance to clinical and subclinical diseases does exist in growing pigs, and suggests that selective breeding for resistance could be successful.

Geographic Patterns of Genetic Variation in Eucalyptus globulus ssp. globulus and a Revised Racial Classification

1999 ◽  
Vol 47 (2) ◽  
pp. 237 ◽  
Author(s):  
G. W. Dutkowski ◽  
B. M. Potts
Keyword(s):  
Genetic Variation ◽  
Eucalyptus Globulus ◽  
Multivariate Analyses ◽  
Basic Density ◽  
Field Trials ◽  
Racial Classification ◽  
Regional Patterns ◽  
Growth And Survival ◽  
Geographic Patterns ◽  
Quantitative Genetic

The geographic patterns of genetic variation in a wide variety of quantitative traits were studied in Eucalyptus globulus ssp. globulus and its intergrades, leading to a revised racial classification. The analysis was based on 35 traits assessed in five field trials in northern Tasmania from approximately 500 open-pollinated families, encompassing 49 collection localities in native stands. There were significant differences between the collection localities for most traits. While growth and survival traits exhibited weak spatial structuring, there were clear regional patterns in bark thickness, wood basic density, flowering precocity and some aspects of juvenile leaf morphology. There were a number of significant correlations between trait locality means, but few simple correlations between the regional patterns observed and climate. Multivariate analyses indicated that the localities could be effectively amalgamated into larger, geographically concordant races. A hierarchy of five major groupings of 13 races and 20 subraces is proposed to account for most of the quantitative genetic variation while allowing for outliers and intermediate populations. Some areas of the distribution may need further sampling to more accurately elucidate their racial affinities, especially those with traits of high economic importance.

scholarly journals Genetic Variation and Correlations between Growth and Wood Density of Calycophyllum spruceanum at an Early Age in the Peruvian Amazon

2006 ◽  
Vol 55 (1-6) ◽  
pp. 217-228 ◽  
Author(s):  
Sotelo Montes ◽  
R. E. Hernández ◽  
J. Beaulieu ◽  
J. C. Weber
Keyword(s):  
Genetic Variation ◽  
Genetic Control ◽  
Wood Density ◽  
Amazon Basin ◽  
Genetic Correlations ◽  
Basic Density ◽  
Ground Level ◽  
Wood Properties ◽  
Stem Diameter ◽  
Peruvian Amazon

Abstract Calycophyllum spruceanum (Benth.) Hook. f. ex K. Shum. is an important timber-tree species in the Peruvian Amazon Basin. As farmers and industry often use wood from young trees, it is important to investigate variation in juvenile wood properties in this species. A provenance/progeny test was established to evaluate genetic variation in growth and wood properties of young trees, the strength of their genetic control as well as their interrelationships both at the genetic and the phenotypic level in different planting zones. In this paper, results are presented for tree height and stem diameter (near ground level) at 16, 28 and 39 months; and stem diameter and basic density of the wood at breast height at 39 months. Significant variation due to provenances and especially due to families within provenances was found in growth and wood density. Phenotypic and genetic correlations indicated that larger trees tended to have denser wood. Wood density had higher heritability than height and diameter; and genetic control over height, diameter and density was generally highest in the planting zone where trees grew most rapidly.

Genetic parameters of carcass quality in Down cross sheep

1968 ◽  
Vol 10 (2) ◽  
pp. 183-191 ◽  
Author(s):  
J. C. Bowman ◽  
J. E. Marshall ◽  
J. S. Broadbent
Keyword(s):  
Genetic Variation ◽  
Genetic Parameters ◽  
Carcass Traits ◽  
Genetic Correlations ◽  
Carcass Quality ◽  
Correction Factors ◽  
Muscle Area ◽  
Eye Muscle ◽  
Additive Genetic Variation ◽  
Commercial Value

This report gives an account of the paternal half-sib analysis of carcass quality, based on commercial joint dissection, on Down cross sheep collected in the four years 1962–65 inclusive. It also includes a discussion of the multiplicative correction factors used, and the phenotypic and genetic correlations between all the traits, estimated from the pooled within-farm, within-year analysis. It shows that there is very little genetic variation for many of the characters but that the percentage leg, percentage best end, age at slaughter and eye-muscle area have much additive genetic variation remaining for worthwhile response to be expected from selection. These three carcass traits are also the most important characters in determining the commercial value and saleability of lamb. From the results obtained it is argued that there is still much genetic variation for fat development in sheep.

Variation in the morphology and flowering time of cluster clover (Trifolium glomeratum L.) and its relationship to distribution in southern Australia

1995 ◽  
Vol 46 (5) ◽  
pp. 1027 ◽  
Author(s):  
FP Smith ◽  
PS Cocks ◽  
MA Ewing
Keyword(s):  
Genetic Variation ◽  
Flowering Time ◽  
Seed Mass ◽  
Annual Rainfall ◽  
Strongly Correlated ◽  
Summer Maximum ◽  
Maximum Temperatures ◽  
Pattern Of Variation ◽  
Growth Habits

Cluster clover is a widely distributed and ecologically successful introduced legume in southern Australia. In an attempt to understand the role of genetic variation in this success, morphological and physiological traits were measured in 94 accessions from southern Australia and 6 from the Mediterranean basin. Flowering time ranged from 105 to 185 days after sowing, but was not strongly correlated with annual rainfall or length of growing season at the site of collection. Variation in other traits partitioned the populations into two morphs which, apart from flowering time and leaf marker, were largely homogeneous. The morphs differed significantly in floret number per inflorescence (22 v. 32-37) and seed mass (379 8g v. 523 8g), had different growth habits and strong within-morph associations between leaf markers and stipule and petal coloration. The morphs differed in their distributions within southern Australia and the pattern of distribution was related to summer maximum temperatures, winter minimum temperatures and spring rainfall. These results demonstrate that genetic variation has been important to the success of cluster clover and suggests that the variation is organized. The pattern of variation observed and its relationship to ecogeography is consistent with findings for other highly inbreeding species. A map of the species distribution in Western Australia is presented.

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