Antioxidant response mechanisms and thermotolerance thresholds in cotton (Gossypium hirsutum L.) under progressive heat stress
Bibliographic record
Abstract
Rising global temperatures are pushing cotton production into increasingly hostile thermal environments, yet the biochemical boundaries of cotton thermotolerance remain poorly mapped. This research characterized antioxidant enzyme responses and oxidative damage indicators in cotton (cv. Deltapine 1646) seedlings exposed to progressive heat stress (30, 38, 42, and 46 °C) for 72 hours in controlled environment chambers at the University of Saskatchewan during 2022. Antioxidant enzyme activities (SOD, CAT, APX, GR, POD) increased significantly at 38 and 42 °C but declined sharply at 46 °C, revealing a thermotolerance threshold between 42 and 46 °C. Malondialdehyde content rose 2.4-fold at 42 °C and 4.8-fold at 46 °C relative to controls. Proline accumulation peaked at 42 °C. Leaf photosynthetic rate declined linearly with temperature, falling 67% at 46 °C. These findings define a biochemical tipping point where cotton antioxidant defenses become overwhelmed, with direct implications for breeding programs targeting heat-resilient cultivars.
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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 | 0.011 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.002 |
| 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 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".