Effects of source and placement of phosphorus on concentration of cadmium in the grain of two durum wheat cultivars
Bibliographic record
Abstract
Cadmium is toxic to humans. Because it enters the food chain through plant uptake, application of phosphorus fertilizer carrying Cd as an impurity may increase the Cd concentration of cereal grains above proposed threshold values. Field experiments were conducted to determine the effect of two phosphorus fertilizers on Cd concentration of two durum wheat ( Triticum turgidum L. var. durum) cultivars, a low Cd accumulator (Arcola) and a high accumulator (Kyle) grown in two soils of southwestern Saskatchewan, Canada. Phosphorus was applied as monoammonium phosphate (15 mg Cd kg-1) and as triple superphosphate (75 mg Cd kg-1) at a rate of 18 kg P ha-1. The fertilizer was applied in a mid-row band or in the seed row. Nitrogen was applied as urea or as ammonium sulphate. Variability in Cd concentration was at tributed primarily to genotype and environment, which accounted for 41% and 29% of the explained variability, respectively. The Cd concentration of Arcola averaged 80 µg kg-1, while that of Kyle averaged 143 µg kg-1. In contrast, fertilization accounted for only a small proportion of the explained variability, with phosphorus treatments accounting for 3% of the model sums of squares, and N sources accounting for less than 1%. Phosphorus fertilization increased the Cd concentration of Arcola, regardless of source or placement, but the proportion of samples with Cd concentration above 100 µg kg-1 remained unchanged at 17%. In the case of Kyle the Cd concentration increased only when the fertilizer was seed-placed, but in this case the proportion of samples with Cd concentration above 100 µg kg-1 increased from 67 to 90%. The effect of P appeared to result from the effects of fertilizer on plant density and vigour rather than from Cd impurities in the fertilizer. Key words: Cadmium concentration, cadmium uptake, durum wheat, fertilization, phosphorus, fertilizer placement, phosphorus source
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 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".