Parameters affecting germinability and seed bank dynamics in dimorphic achenes of <i>Centaurea solstitialis</i> in California
Bibliographic record
Abstract
Yellow starthistle (Centaurea solstitialis L.) is a major rangeland weed pest in California and other western states. Two complementary aspects of seed biology were examined: germination and seed bank dynamics. Achenes were tested for changes in germinability over time using various light, temperature, and moisture treatments. Soil cores were collected over time to monitor changes in achene density. Both plumed and nonplumed achenes exhibited photo reversible responses to red and far-red light. White and red light enhanced germination above that occurring in darkness. Achenes showed seasonal changes in germinability, which were characteristic of conditional dormancy. Exposure of achenes to field conditions during summer alleviated primary dormancy, allowing germination to occur at higher temperatures and lower substrate moisture. Nonplumed achenes collected in winter showed reduced germinability at or above moderate temperatures under both single and multiple light exposures. Imbibition and moderately low temperatures with subsequent drying induced secondary conditional dormancy in some achenes. Plumed achenes dominated the soil seed bank before the rainy season, then declined rapidly following rain. Nonplumed achenes peaked after rains began, then declined. Although nearly all achenes were depleted after 4 years, both types remained, showing annual cycles of high and low germinability in autumn and late spring, respectively.Key words: light, phytochrome, conditional dormancy, longevity.
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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".