Relationships of<i>Pythium</i>isolates and sweet pepper plants in single-plant hydroponic units
Bibliographic record
Abstract
An isolate of Pythium aphanidermatum and five isolates of Pythium dissotocum were examined for ability to colonize and produce symptoms in root systems of sweet pepper grown in aerated nutrient solution in single-plant hydroponic units in a research greenhouse. Repetitions of the study were conducted in April 2000, February 2001, and May 2001. Roots were inoculated by immersion for 30 min in a suspension of 5 × 103 zoospores/mL nutrient solution. All isolates rapidly colonized the root systems and increased density of cortical cells with cytoplasmic granulation in all repetitions. Symptoms produced by a given isolate differed but generally overlapped with those caused by other isolates and variously included zones of root-tip browning of different sizes and hues (all isolates), expansive browning (P. aphanidermatum) or yellowing (P. dissotocum), architectural changes (chiefly stunting, stubbiness, and proliferation of roots with all isolates), root swelling (P. dissotocum), and callus cell proliferation (P. dissotocum). Patterns of increase in incidence of brown root tips and of expansive root discoloration differed among isolates and among experimental repetitions. Circumstantial evidence suggested that higher temperature and light conditions of May 2001 promoted disease caused by P. aphanidermatum and P. dissotocum isolates compared with February 2001 and, in some instances, April 2000. Observations indicated that moderate differences in temperature, light, or other environmental variables among the repetitions markedly influenced the expression of discoloration and of other symptoms in colonized roots. All isolates reduced various growth parameters of the roots and shoots in one or more repetitions; however, relationships of colonization and symptoms to growth were generally unclear. Collectively, the data have applications for evaluating control methods in single-plant hydroponic units and contribute to an understanding of the epidemiology of root rot caused by Pythium spp. in greenhouse pepper.
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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 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".