Quantitative genetics of lodgepole pine (Pinus contorta) wood quality traits in Sweden
Bibliographic record
Abstract
Stem bending, breakage, and general instability of lodgepole pine has been a major problem in northern Sweden due to low stem stiffness. The overall aim of this thesis was to evaluate the potential incorporation of wood quality traits into lodgepole pine advanced breeding programs. To achieve this, 823 increment cores were sampled from 207 half-sib families at two progeny trials of lodgepole pine and genetic variations in wood density, microfibril angle (MFA), modulus of elasticity (clearwood stiffness; MOEs), radial fibre width (RFW), tangential fibre width (TFW), fibre wall thickness (FWT), and fibre coarseness (FC) were characterised. \nTo quantify genotype by environment interactions (G × E) for growth and stiffness and to evaluate performance of provenances, diameter at breast height (DBH) and dynamic stiffness of standing trees (MOEtof) were studied, using six 33-36 year-old lodgepole progeny trials within three different breeding zones in northern Sweden. To evaluate genetic gains in selection for an early MFA transition from juvenile to mature wood, six different regression functions were fitted to the MFA profile of each tree to delineate the age variation in MFA transition. \nNarrow-sense heritability estimates (ℎ2) ranged from 0.10 to 0.32 for DBH and from 0.18 to 0.76 for wood quality traits. Unfavourable genetic correlations between growth and stiffness were observed, implying that selection for a 1% increase in DBH alone, would confer 5.5% and 2.3% decreases in lodgepole pine MOEs and MOEtof, respectively. \nResults of the studies in this thesis indicate that simultaneous improvement of DBH and stiffness is achievable when an optimal selection index combining both traits is implemented. Additionally, it is possible to select for an earlier MFA transition from juvenile to mature wood, and thus, decreasing the proportion of the log containing juvenile wood in lodgepole pine selective breeding programs. Finally, G × E was only significant for stiffness within the northern most breeding zone. To achieve the highest stiffness for lodgepole pine, provenances of Yukon origin should be planted at lower latitudes and those of British Columbia (BC) origin should be planted at lower elevations within the tested breeding zones.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".