Effets du N minéral et du génotype de la plante sur la croissance et la nodulation de <i>Faidherbia albida</i>
Bibliographic record
Abstract
Sahelian soils are recognized for their low N content, but their mineral N concentrations can often be high enough to inhibit N2 fixation in cultivated legumes. However, the quest for symbiotic plant genotypes tolerant of mineral N is poorly documented for nitrogen-fixing trees. The behaviour of N2 fixing symbioses with regard to nitrogen fertilization was observed in different Faidherbia albida (Del) A. Chev. genotypes. Twelve distinct lineages of the species, obtained from four regions of western Africa, were cultivated for 75 days in the presence of 06 mol·m3 N provided as NH4NO3. Plants were separately inoculated with two Bradyrhizobium strains, and cultivated on sandy soil in a nursery. Aerial and root parts lengths and masses, collar diameters, and ratios of height to length (H/P) of taproot, and aerial to root (MA/MR) parts masses increased with increased N level. Plants showed significant growth differences linked with seed origin, and with lineage for a same origin. Genotypical variations were observed for concentrations as well as C and N total uptakes, C/N ratio measured in aerial parts, and N2 fixation. Nodule number and mass were greatly reduced in the presence of 2 mol·m3 N. The extent of this reduction was dependent, to a lesser degree, on seed origin and Bradyrhizobium strain. Data show that F. albida Bradyrhizobium symbiosis is highly sensitive to mineral N. It is suggested that selection of symbiotic partners for tolerance to mineral N might greatly improve the agronomic behaviour of F. albida.Key words: Faidherbia albida, lineages, Bradyrhizobium, symbiosis, nodulation, growth, ammonium nitrate.
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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".