Untimely Fall Harvest Affects Dry Matter Yield and Root Organic Reserves in Field‐Grown Alfalfa
Bibliographic record
Abstract
The regrowth interval between the last summer harvest and the fall harvest is a major determinant of alfalfa (Medicago sativa L.) persistence and spring regrowth. This study assessed the impact of the timing of a fall harvest on persistence, dry matter yield (DMY), and root carbohydrate and N reserves of field‐grown alfalfa. Two cultivars (AC Caribou and WL 225) were harvested either only twice during the summer or three times with the third harvest taken 400, 500, or 600 growing degree days (GDD) after the second summer harvest. Plant density was not affected by a fall harvest across three production years (1997 to 1999). The DMY of the first harvest in the second production year (1998) was significantly reduced by prior fall harvests taken at 400 or 500 GDD. However, the seasonal DMY in 1998 was higher with the 500 or 600 GDD harvest management than with the two harvest system. Root dry weight (DW) was generally reduced by a third harvest in the fall, especially when taken at 400 GDD. Amounts of root carbohydrate reserves (raffinose family oligosaccharides [RFO], sucrose, and starch), as well as the amounts of total amino acids and soluble proteins were significantly reduced by harvesting at 400 or 500 GDD. Untimely fall harvest reduced alfalfa spring regrowth by impeding the accumulation of both carbohydrate and N reserves. Seasonal DMY remained advantageous as long as an interval of 500 or 600 GDD was kept between the last summer and the fall harvests.
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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) | 0.000 | 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 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".