Seed bank dynamics of <i>Onopordum acanthium</i>: emergence patterns and chemical attributes
Bibliographic record
Abstract
Summary Cypselas (fruits) of Scotch thistle ( Onopordum acanthium ) germinate unpredictably over a long period of time. We evaluated the effects of soil type, burial depth and collection date on the emergence patterns of two populations of O. acanthium , ESW and Quarry (Q). From each of four separate collections made throughout 1996, five replicates of 200 cypselas each were placed on the surface or buried at depths of 3 or 15 cm in both sand and silt‐loam soils (i.e. field conditions) and emergence was recorded biweekly between August 1996 and September 1999. Emergence was intermittent over the 3 years, with a higher total percentage from silt loam (17%) than from sand (9%), and from 3 cm depth (18%) compared with the surface (8%). After 3 years, all remaining viable, split (germinated but not emerged), decayed and unfilled cypselas were retrieved. Total germination over the 3 years (emerged plus split) was up to 77% at 3 cm in silt loam but always less than 10% at 15 cm in both soils for both populations. Although a higher percentage of cypselas germinated under controlled conditions when retrieved from loam compared with sand (89% vs. 66%), a significant number from all treatments did not germinate until scarified. Cypselas that ripened under the warmest temperature (collection 3) had the highest emergence in the year of collection (1996), while more of those that ripened under cooler temperatures (collections 1 and 4) emerged in later years (1998 and 1999). Both initial and later emergence patterns for both populations varied greatly with collection date. This may be the first time that seedling emergence from the seed bank for different collections has been monitored over several years. We compared waxes, lignins and soluble phenolics in the coats of cypselas retrieved from soil (early germinators) with those that germinated only after scarification. More surface wax was found in dormant cypselas. Understanding these complex germination/emergence patterns may help develop control policies for O. acanthium .
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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) | 0.002 | 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 teacher head, 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".