Contrasting growth pattern and nitrogen economy in ancient and modern wheat varieties
Bibliographic record
Abstract
Pourazari, F., Vico, G., Ehsanzadeh, P. and Weih, M. 2015. Contrasting growth pattern and nitrogen economy in ancient and modern wheat varieties. Can. J. Plant Sci. 95: 851–860. Nutrient availability, especially nitrogen (N) availability, is a limiting factor for crop production in many regions of the world. Modern crop varieties often produce high yields under high resource availability, whereas ancient varieties are expected to have characteristics more suitable under low resource availability. To test this expectation, we compared the growth and N use efficiency (NUE) of some varieties of ancient hulled wheat, Triticum turgidum spp. dicoccum, and modern free-threshing wheat, T. aestivum and T. turgidum spp. durum. The wheats were grown under different nutrient fertilization (F) levels in two contrasting environments (field in Iran and outdoor growth container in Sweden). Grain yield was significantly higher in modern varieties than in ancient varieties, regardless of fertilization level. In contrast, N uptake efficiency (i.e., mean N in the plant during the main growth period over N in the initial seed grain) and grain N concentration were generally higher in the ancient varieties. Nitrogen use efficiency, defined as the ratio of the grain N content to the sown seed N content, was higher in the ancient varieties only at lower nutrient supply, because in modern varieties higher nutrient supply resulted in a marked increase in NUE through greatly enhanced grain-specific N efficiency (grain yield per mean plant N content during the main growth period). The modern varieties also showed greater fertilization responses in above-ground biomass and leaf area than ancient varieties. The results are relevant in the context of wheat breeding for nutrient use efficiency.
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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 | 0.001 | 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 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".