Multiple mechanisms for seed dormancy regulation in shadscale (<i>Atriplex confertifolia</i>: Chenopodiaceae)
Bibliographic record
Abstract
Shadscale (Atriplex confertifolia (Torr. & Frem.) Wats.) is a dominant shrub species of western North American deserts. Its one-seeded utricles are enclosed in bracteoles, and its seeds are highly dormant at dispersal. We examined the role of soluble inhibitors, bracteole effects, after-ripening, and chilling in regulating dormancy for six shadscale populations. Seeds in bracteole-enclosed fruits required chilling to become germinable, and the fraction responsive to chilling was small for recently harvested seeds. This fraction increased during dry storage for 24 weeks, but the rate of increase decreased asymptotically. After-ripening rate was an exponential function of storage temperature over the range 2250°C. After-ripening models based on these nonlinear relationships for each of four seed populations accounted for 96% of the change in the chilling-responsive fraction during 3 years of laboratory storage. Rate of change in the chilling-responsive fraction during laboratory storage was log-linearly related to the chilling-responsive fraction for recently harvested seeds. Excision of utricles from recently harvested fruits increased the chilling-responsive fraction but did not generally eliminate the chilling requirement. Leaching or dewinging to remove soluble inhibitors increased germination of otherwise nondormant seeds but did not relieve primary dormancy. Knowledge of dormancy loss mechanisms will facilitate prediction of germination phenology and seed bank persistence for shadscale under fluctuating field conditions.Key words: after-ripening, germination, saltbush, soluble inhibitor, stratification, thermal time.
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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".