Nitrogen Fixation Associated with Suillus tomentosus Tuberculate Ectomycorrhizae on Pinus contorta var. latifolia
Bibliographic record
Abstract
BACKGROUND AND AIMS: Tuberculate ectomycorrhizae are a unique form of ectomycorrhiza where densely packed clusters of mycorrhizal root tips are enveloped by a thick hyphal sheath to form a tubercle. The functional significance of such a unique structure has not previously been established. The purpose of the present study was to investigate and measure the potential nitrogenase activity associated with Suillus tomentosus/Pinus contorta tuberculate ectomycorrhizae in two stand ages, young and old, and across a range of nitrogen-poor soil conditions. METHODS: Short roots were compared with other mycorrhizae and non-mycorrhizal secondary roots using tuberculate ectomycorrhizae. Assessment of nitrogenase activity was determined and quantitative measurements were taken on tuberculate ectomycorrhizae in situ in a variety of different circumstances, by using an adaptation of the acetylene reduction assay. KEY RESULTS: Significant nitrogenase activity was measured associated with S. tomentosus/P. contorta tuberculate ectomycorrhizae whereas no nitrogenase activity was measured with non-tuberculate mycorrhizae or secondary roots without mycorrhizae. Average nitrogenase activity ranged from undetectable to 5696.7 nmol C2H4 g(-1) tubercle 24 h(-1). Maximum nitrogenase activity was 25,098.8 nmol C2H4 g(-1) tubercle 24 h(-1). Nitrogenase activity was significantly higher in young stands than in old stands of P. contorta. Season or some covariate also seemed to affect nitrogenase activity and there was suggestion of a site effect. CONCLUSIONS: Suillus tomentosus/P. contorta tuberculate ectomycorrhizae are sites of significant nitrogenase activity. The nitrogenase activity measured could be an important contribution to the nitrogen budget of P. contorta stands. Season and stand age affect levels of nitrogenase activity.
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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 | 0.000 |
| 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) | 0.002 | 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".