Growth and Physiological Response of Timothy to Elevated Carbon Dioxide and Temperature under Contrasted Nitrogen Fertilization
Bibliographic record
Abstract
ABSTRACT Climate change is expected to affect the growth and metabolism of many economically important plants including timothy (Phleum pratense L.), a major forage grass species in eastern Canada and northern Europe. Our objective was to assess the impacts of predicted increases in CO2 concentration and temperature, under contrasted N fertilization, on timothy biomass, leaf photosynthesis, and nonstructural carbohydrate concentration. Plants were grown in growth chambers under either 400 or 600 μL L−1 of CO2 and at a day/night temperature of either 22/10°C or 25/15°C, and they were fertilized with 0, 60, or 120 kg N ha−1. Two sequential harvests were taken following a 6‐wk establishment period. Elevated CO2 concentration did not affect forage biomass and increased root biomass only at first harvest, but it increased leaf photosynthesis and total soluble sugar concentration mostly when N was not limiting (120 kg N ha−1). Increased temperature reduced forage and total biomass and soluble sugar concentrations at the second harvest under 120 kg N ha−1. Combined increases of temperature and CO2 concentration (600 μL L−1 and 25/15°C) had no effect on biomass yield, but it increased leaf photosynthesis and nonstructural carbohydrates concentration compared to current conditions. Our findings show that predicted future conditions of elevated temperature and CO2 concentration will have little effect on the yield of timothy while their effect on photosynthesis and forage nonstructural concentration will depend on N availability.
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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".