Genetic variation for tolerance to defoliation in Cirsium arvense
Bibliographic record
Abstract
The agricultural weed, Cirsium arvense (creeping, Canada, or Californian thistle), is notorious for its ability to tolerate defoliation by mowing, herbivores, or herbicides, which is facilitated by the growth of adventitious shoots from its extensive clonal root system. In an outdoor potted plant experiment, we examined the tolerance of 36 unique genotypes of C. arvense to defoliation by establishing pairs of clonal replicates that were assigned to a clipped, or unclipped treatment. Three clippings were applied from spring to early summer to simulate repeated mowing. The average final percentage reduction caused by the repeated clipping treatment was 18%, 72%, 32%, and 50% for shoot biomass, root biomass, number of shoots, and maximum plant height, respectively. Nearly all individual genotypes were negatively affected by the clipping. However, some genotypes overcompensated, and achieved greater shoot biomass, number of shoots, or increased height than their unclipped counterparts. No genotypes were able to overcompensate, or fully tolerate, the lost root biomass due to repeated clipping. Genetic variation for tolerance to defoliation was detected for the number of shoots, plant height, and for relative growth rate. With regard to relative growth rate, significant genetic variation was not detected until after the third clipping event, indicating that genotypes were equally tolerant to a moderate degree of defoliation, but upon more severe defoliation, genetic differences were evident. Since repeated defoliation is a recommended control technique for this weed, selection for more tolerant genotypes is possible, and should be taken into account for the management of this weed.
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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 | 0.001 | 0.001 |
| 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".