<i>Bradyrhizobium japonicum</i> mutants allowing improved nodulation and nitrogen fixation of field-grown soybean in a short season area
Bibliographic record
Abstract
In short-season soybean production areas, low soil temperature is potentially a major factor limiting plant growth and yield. Although Bradyrhizobium japonicum strain 532 C is widely used in inoculants in Canadian soybean production, and USDA 110 is widely used in American soybean production, they are both inhibited by low temperatures. Genistein is an important plant-to-bacteria signal compound secreted by soybean roots. The addition of genistein has proven to be an effective means of generating increases in nitrogen fixation and yield but genistein is expensive. We used UV mutagenesis to make 10 mutants from USDA 110 that express nod genes without the addition of plant-to-bacteria signal compounds such as genistein. A field experiment was conducted at the Lods Agronomy Research Centre in southwestern Quebec in 1998 and 1999. The treatments consisted of factorial combinations of inoculant type (no inoculant (control) and inoculants containing the mutants Bj 30050, Bj 30051, Bj 30052, Bj 30053, Bj 30054, Bj 30055, Bj 30056, Bj 30057, Bj 30058, Bj 30059 and the wild type USDA110 or 532 C) and soybean cultivar (Bayfield and Maple Glen). The experiment was structured following a randomized complete block design with four blocks. Data were collected on nodule number, nodule dry weight, shoot nitrogen yield and total nitrogen fixation at five development stages. Averaged over the 2 years of the study, when pods were 2 cm long at one of the four uppermost nodes on the main stem (R4), inoculation with Bj 30055 and Bj 30058 resulted in greater nodule number (23 and 14%, respectively), nodule dry weight (16 and 13%, respectively), shoot nitrogen yield (19 and 21%, respectively) and total nitrogen fixation (10·9 and 12·7%, respectively) than 532 C, which is currently used in Canadian inoculants. The cultivar Bayfield produced more nodules, and higher nodule weight than Maple Glen, but there were no differences between the cultivars for shoot nitrogen yield and total nitrogen fixation.
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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) | 0.001 | 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 | 0.001 |
| 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".