Response to water stress of soil enzymes and root exudates from drought and non-drought tolerant corn hybrids at different growth stages
Bibliographic record
Abstract
Song, F., Han, X., Zhu, X. and Herbert, S. J. 2012. Response to water stress of soil enzymes and root exudates from drought and non-drought tolerant corn hybrids at different growth stages. Can. J. Soil Sci 92: 501–507. Drought tolerant corn hybrids (Zea mays L.) are an excellent model to evaluate the effect of water stress on rhizosphere functions. The purpose of this study was to investigate the influences of water stress on soil pH, enzyme activities, and root exudates from corn. Two corn hybrids, Baidan 9 (drought tolerant) and Baidan 31 (non-drought tolerant) were grown in soil-filled pots for pH and enzyme assays and in hydroponics culture for root exudate analysis. Water stress was imposed at four growth stages: seedling, elongation, tasseling and grain-filling stages. Soil pH was lower in the rhizosphere than bulk soil, but was not affected by water deficiency. Water stress increased protease activity at the seedling stage, but reduced its activities at other stages compared to the control. A significant positive correlation was observed between pH and alkaline phosphatase activity under water stress. Compared to Baidan 31, the rhizosphere of drought-tolerant Baidan 9 had greater protease and catalase activities at all growth stages, greater alkaline phosphatase, lower acid phosphatase and greater invertase activities at elongation, tasseling and filling stages. Osmotic stress increased the organic acid concentration (malic, lactic, acetic, succinic, citric and maleic acids) in root exudates of Baidan 9 and Baidan 31; as well there was a greater fumaric acid concentration in Baidan 31 under osmotic stress than without stress. The increased soil enzyme activities and organic acids exuded from the rhizosphere of plants under water stress might contribute to drought tolerance in corn hybrids.
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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 | 0.001 |
| 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".