Suppression of Powdery Mildew on Greenhouse-Grown Cucumber by Addition of Silicon to Hydroponic Nutrient Solution Is Inhibited at High Temperature
Bibliographic record
Abstract
Silicon amendments to hydroponic nutrient solutions have been used successfully in Canada to suppress powdery mildew (PM) caused by Sphaerotheca fuliginea on cucumber (Cucumis sativus). In contrast, preliminary trials in Florida greenhouses failed to achieve the level of disease suppression reported in the literature for Canadian studies. A series of greenhouse experiments were conducted in Florida to determine the factors involved in reducing the effectiveness of silicon amendments for PM suppression on cucumber. Three horticultural practices (cultivar, nutrient solution formula, and rooting medium) and two environmental factors (light intensity and temperature) were tested in combination with silicon amendments for their effects on the suppression of PM on cucumber. When plants were irrigated with a standard nutrient solution amended with potassium silicate at 0 mg/liter, the cucumber cv. Vetomil was found to be resistant and cvs. Corona, Cilla, Farbio, and Toska were found to be susceptible to PM. Susceptible cultivars irrigated with potassium silicate at 100, 150, or 200 mg/liter exhibited a slight but statistically significant reduction in PM over the course of a 49-day trial. Although PM in the cultivar trial was slightly lower in treatments with added silicon, disease suppression with silicon was not commercially useful because it failed to increase fruit yields. Nutrient solution formula, rooting medium, and light intensity had no effects on the levels of PM suppression, regardless of whether plants were irrigated with potassium silicate at 0 or 100 mg/liter. Temperature was found to act in a synergistic manner with silicon. The greatest effect of temperature on PM suppression was observed at 20°C in which cucumber plants, irrigated with silicon at 100 mg/liter, exhibited significant reductions in the numbers of PM colonies per leaf. Disease suppression by silicon was observed at 25 and 30°C, but the magnitude of the disease suppression was significantly lower than when plants were maintained at 20°C. The effect of temperature on PM suppression by silicon may explain the difference in results between previous experiments in Canada, where greenhouse temperatures averaged 20 to 25°C, and the current study in Florida, where greenhouse temperatures averaged 24 to 32°C.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 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".