Effectiveness of border areas in confining the spread of transgenic <i>Brassica napus</i> pollen
Bibliographic record
Abstract
The development of transgenic Brassica napus L. cultivars requires field trials in agricultural settings. For field testing of transgenic constructs that have not been granted full environmental release, current Canadian Government regulations require either large isolation zones (200 m) or 10 m wide borders of synchronously flowering, non-transgenic B. napus to contain transgenic pollen. To investigate the effectiveness of border areas in containing transgenic B. napus pollen, border areas 15 to 30 m wide were planted around 30 m × 60 m central plots of bromoxynil-herbicide-resistant transgenic B. napus strains. Four field trials were conducted at Carman and Winnipeg, Manitoba, Canada in 1994 and 1995. Seed samples were harvested from the border area at 0, 2.5, 5, 10, and 15 m for the four cardinal directions and additionally at 20, 25, and 30 m for two cardinal directions. These seed samples were planted in the field in 1995 and 1996 and the seedlings screened for the presence of bromoxynil-resistant plants (i.e., from outcrossed seeds). Distance from the central plot significantly affected outcrossing rates while environment (site–year) and direction effects were non-significant. Outcrossing rates averaged 0.70% at 0 m and declined exponentially to 0.02% at 30 m. More than four-fifths of the total outcross events detected occurred in the first 10 m of border area indicating that border areas effectively reduce pollen-mediated gene flow in B. napus but cannot completely eliminate it. Key words: Transgenic canola; Brassica napus; pollen containment
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| 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".