Low soil temperature inhibits the effect of high nutrient supply on photosynthetic response to elevated carbon dioxide concentration in white birch seedlings
Bibliographic record
Abstract
To investigate the interactive effects of soil temperature (T(soil)) and nutrient availability on the response of photosynthesis to elevated atmospheric carbon dioxide concentration ([CO(2)]), white birch (Betula papyrifera Marsh.) seedlings were exposed to ambient (360 micromol mol(-1)) or elevated (720 micromol mol(-1)) [CO(2)], three T(soil) (5, 15 and 25 degrees C initially, increased to 7, 17 and 27 degrees C, respectively, 1 month later) and three nutrient regimes (4/1.8/3.3, 80/35/66 and 160/70/132 mg l(-1) N/P/K) for 3 months in environment-controlled greenhouses. Elevated [CO(2)] increased net photosynthetic rate (A(n)), instantaneous water-use efficiency (IWUE), internal to ambient carbon dioxide concentration ratio (C(i)/C(a)), triose phosphate utilization (TPU) and photosynthetic linear electron transport to carboxylation (J(c)), and it decreased actual photochemical efficiency of photosystem II (DeltaF/F(m)'), the fraction of total linear electron transport partitioned to oxygenation (J(o)/J(T)) and leaf N concentration. The low T(soil) suppressed A(n), transpiration rate (E), TPU, DeltaF/F(m)' and J(c), but it increased J(o)/J(T). The low nutrient treatment reduced A(n), IWUE, maximum carboxylation rate of Rubisco, light-saturated electron transport rate, TPU, DeltaF/F(m)', J(c) and leaf N concentration, but increased C(i)/C(a). There were two-factor interactions for C(i)/C(a), TPU and leaf N concentration, and a significant effect of CO(2) x T(soil) x nutrient regime on A(n), IWUE and J(c). The stimulations of A(n) and IWUE by elevated [CO(2)] were limited to seedlings grown under the intermediate and high nutrient regimes at the intermediate and high T(soil). For J(c), the [CO(2)] effect was significant only at intermediate T(soil) + high nutrient availability. No significant [CO(2)] effects were observed under the low T(soil) at any nutrient level. Our results support this study's hypothesis that low T(soil) would reduce the positive effect of high nutrient supply on the response of A(n) to elevated [CO(2)].
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 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) | 0.000 | 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".