Effect of Temperature on Germination Characteristics of Glyphosate-Resistant and Glyphosate-Susceptible Kochia (<i>Kochia scoparia</i>)
Bibliographic record
Abstract
Glyphosate-resistant (GR) kochia is an increasing concern for growers across the U.S. Great Plains and Canadian prairies. Integrated strategies to mitigate resistance will require an improved understanding of the seed germination dynamics of GR kochia populations. Experiments were conducted to characterize the germination of GR vs. glyphosate-susceptible (GS) kochia populations under different constant (5 to 35 C) and alternating (5/10 to 30/35 C) temperatures. Seven GR and two GS populations were collected from wheat–fallow fields in northern Montana. Selected lines of GR and GS were obtained after three generations of recurrent group selection in the greenhouse. The GR-selected lines had 4.1 to 10.8 average EPSPS copies compared with a single EPSPS gene copy for the GS selected lines. Four out of seven GR selected lines had lower final germination ( d parameter) and took more time to complete 50% cumulative germination (I 50 values) under all constant and alternating temperatures, compared with the GS selected lines. Those GR selected lines also had a delayed germination initiation (I 10 values), particularly at lower temperatures (5 to 10 C constant or 5/10 C alternating). In contrast, the final germination ( d ) of the other three GR selected lines did not differ from GS lines at a majority of temperatures tested. The I 50 values of those GR lines were also comparable to GS lines under a majority of the temperatures. There was no significant correlation of observed percent cumulative germination and EPSPS gene copy number of selected kochia lines. The temperature-dependent dormancy and altered germination characteristics of the four GR kochia lines reflect the common selection of resistance and avoidance (glyphosate or other preseeding treatments) mechanisms. This is most likely attributed to long-term, intensive cropping practices and less diverse weed control methods, rather than a fitness cost or pleiotropic effect of multiple copies of the EPSPS gene.
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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".