Physiological Basis of Heterosis for Nitrogen Use Efficiency of Maize
Bibliographic record
Abstract
Abstract Efficient use of nitrogen inputs for concurrent improvements in grain yield and nitrogen use efficiency (NUE) has been recognized as a viable strategy for sustainable agriculture development. Yet, there is little research on the possible physiological basis of maize hybrid heterosis for NUE and measurable traits that are corresponding to the NUE heterosis. A field study was conducted for two years to evaluate the heterosis for NUE and determine the relationship between NUE and its physiological components. Two commercial hybrids, ‘Xianyu335’ and ‘Zhengdan958’, and their parental inbred lines, were grown at 0 (0 N) and 150 kg N ha −1 (150 N), in a randomized complete block design with four replications each year. Compared to their parental lines, both hybrids displayed a significant heterosis, up to 466%, for NUE. N internal efficiency (NIE) accounted for 52% of the variation in heterosis for NUE, while there was generally negligible heterosis for nitrogen recovery efficiency (NRE). Heterosis for NIE and thereby for NUE in maize was ascribed to (i) an earlier establishment of pre-anthesis source for N accumulation, which phenotypically exhibited as a faster leaf appearance rate with higher maximum LAI and photosynthetic nitrogen use efficiency; (ii) a larger amount of N being remobilized from the vegetative tissues, especially from leaves, during the grain filling. Phenotypically, there was notably a rapid reduction in post-anthesis specific weights of leaf and stalk, but with maintained functionally stay-green ear leaves; and (iii) a higher productive efficiency per unit grain N, which was characterized by a reduced grain N concentration and enhanced sink strength.
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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".