A Preliminary Study of Pollen Dispersal in<i>Cannabis sativa</i>in Relation to Wind Direction
Bibliographic record
Abstract
Pollen of Cannabis sativa is disseminated by wind in large amounts and for long distances, and regulations concerning the production of pedigreed seed of industrial hemp, therefore, often call for extremely large isolation distances to prevent unwanted pollination. In Europe and Canada, a standard distance of 5 km is required for the highest classes of hemp seed. This study examines the relative distribution of pollen from an isolated field over the 3-week maximum flowering period, with particular reference to wind direction. The amount of pollen distributed downwind was about six times the amount distributed upwind. In effect, this means that an isolation distance of 5 km on the downwind side is about equivalent to an isolation distance of 0.9 km on the upwind side. In theory, at the experimental site examined, the required isolation area could be reduced by about 58% while still achieving the equivalent of 5 km isolation in all directions. Given that weedy and illegally cultivated plants are widespread, making it difficult to ensure their absence over a distance of 5 km, it seems advisable, when possible, to take advantage of the considerably reduced isolation distance that is necessary on the upwind side. Pollen distribution appeared to follow the expected leptokurtic curve, reducing rapidly with initial distance from the source, but much more slowly with increasing distance. This makes it impossible to guarantee complete absence of potentially contaminating pollen in the field and, for practical purposes, a very low amount of undesired gene flow needs to be tolerated.
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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 | 0.000 | 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".