Occurrence and Characterization of Rhizoctonia spp., Causal Agents of Sheath Diseases Isolated from Rice in Lao PDR
Bibliographic record
Abstract
Sheath diseases of rice are major constraints to rice production in Asia. Collection of sheath disease samples were taken during the dry season (January-May), 2015 and the rainy season (June-November), 2016 from several fields in each of two provinces of Lao PDR. The pathogens were isolated and characterized on morphology, pathogenicity and molecular identification. Nineteen isolates of Rhizoctonia spp. were studied and found that seven isolates were R. solani and twelve isolates were R. oryzae. The R. solani mycelia on PDA were light brown to brown, sclerotia brown in color, globose to irregular shape. On other hand, R. oryzae mycelia on PDA were brown and orange brown, sclerotia were globose to irregular shape, dark brown or light-yellow color. Six isolates of Rhizoctonia with different characteristics were selected to identify using molecular technique. Molecular identification was carried out by PCR technique using primers, ITS5 (5’-GGAAGTAAAAGTCGTAACAAGG-3’) and ITS4 (5’-TCCTCCGCTT ATTGATATGC-3’) to amplify PCR products of ITS1-5.8S-ITS2 region of rRNA gene. The PCR products were about 750 base pairs and subjected to base sequence comparison in GenBank database. The result showed that isolates, SMN1-5, SMC1-2 and VNN were R. solani, while isolates VHN1-3, SMN1-7 and VHN were R. oryzae. Result on pathogenicity evaluation revealed that, the isolate VSV1-2 of R. oryzae which inoculated on a sheath produced the largest average lesion area of 303 mm2, compared to isolate SMN1-5 of R. solani with a result lesion area of 191 mm2. All 19 isolates were pathogenic to rice cultivar (Thadokham 8). The percent study indicates that the R. solani can invade both sheath and leaf of rice cultivar (Thadokham 8), however, R. oryzae invaded only on sheath. In addition, the occurrence and characterization of R. oryzae are reported for the first time in Lao PDR.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 teacher head, 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".