Nitrogen form affects physiological responses and root expansigenous honeycomb aerenchyma in the emergent macrophyte <i>Acorus americanus</i>
Bibliographic record
Abstract
High nitrogen (N) concentrations and high NH 4 + :NO 3 − ratios that are characteristic of heavily eutrophic and constructed wetlands may be detrimental to the growth and establishment of macrophytes in wetlands formed in the oil sands reclamation areas. This study investigates the effects of N form on the physiology, growth, and root expansigenous honeycomb aerenchyma structure of Acorus americanus (Raf.) Raf., an important macrophyte targeted for wetland reclamation in Canada. Three populations of A. americanus were grown in aerated solution culture and provided for up to 3 months with two different concentrations of N (2 mmol·L −1 , 8 mmol·L −1 ) as NH 4 + , NO 3 − , or NH 4 + + NO 3 − . Fresh mass and physiological parameters including gas exchange, chlorophyll fluorescence, stomatal traits, nitrogen and chlorophyll concentration, root morphology, and aerenchyma structure were examined. The effects of N form were concentration-dependent. At 2 mmol·L −1 N, NH 4 + + NO 3 − plants had higher fresh mass, photosynthetic rates, number of first-order roots, root diameter, and maximum root length than those provided solely with NH 4 + or NO 3 − . At 8 mmol·L −1 N, both NH 4 + and NH 4 + + NO 3 − treatments had a negative impact on growth, net photosynthesis, and chlorophyll concentrations, and they also led to thinner and shorter roots with necrotic tips, a significant reduction in fractional root porosity, and a denser aerenchyma with smaller lacunae. The results indicate that high levels of NH 4 + -N may negatively affect the establishment of A. americanus plants in constructed wetlands through its impact on growth, net photosynthesis, and root morpho-anatomy.
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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) | 0.000 | 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 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".