The effect of leaf spots on yield and quality of wheat in southern Saskatchewan
Bibliographic record
Abstract
Although leaf spots have been reported to have a negative effect on yield and quality, the magnitude of the effect of leaf spots on grain yield and quality of wheat cultivars grown on dryland in southern Saskatchewan is not known. Experiments were conducted at Swift Current (Brown soil) and Indian Head (Black soil) for three years to determine effects of leaf spots on grain yield, kernel weight, test weight and protein concentration of wheat. Two fungicides, Folicur 3.6F and Bravo 500 were applied at different growth stages in order to diversify the severity of leaf spots. Three common wheat (T. aestivum L.) cultivars - AC Domain, Laura and AC Elsa and three durum wheat (T. turgidum L. var durum) cultivars with different levels of leaf spot susceptibility were used in this study. The control of leaf spots by fungicides often did not cause an increase of yield, kernel weight, test weight or grain protein concentration in the drier Prairies where yield potential is relatively low. Fungicide treatments significantly increased yield in only two of six location-years (Folicur applied at head emergence in 1997 (0.07-0.13 t ha-1) (P < 0.05) and Folicur applied at flag emergence and/or head emergence in 1998 (0.41-0.47 t ha-1) (P < 0.001) at Indian Head. Fungicide applications significantly increased kernel weight in only three of six location-years (applications at flag leaf emergence at Swift Current (0.8-1.1 mg) (P < 0.05) and Indian Head (1.8-2.0 mg) (P < 0.001) in 1998 and at Indian Head in 1999 (10-1.1 mg) (P < 0.01). An increase of grain protein concentration was only found in treatments of Bravo applications at Indian Head in 1998 (0.3-0.7%) (P < 0.001). It seems that the control of leaf spots tended to have higher effect on yield and quality at Indian Head than Swift Current, it could be attributed to better controls of leaf spots at early milk stage (P < 0.001) and/or higher yield potential at Indian Head (P < 0.001). Although the cultivars used in this study have different leaf spot susceptibility (P < 0.001), there were no consistent cultivar differences in the effectiveness of the fungicides on control of leaf spots and on the yield, kernel weight and other quality characteristics. Leaf spots are a common and potentially severe foliar disease of wheat. Many studies have reported that leaf spots have a negative effect on grain yield (Eyal and Ziv, 1974; King, et al., 1983; McKendry and Henke, 1994), test weight (Milus, 1994) and milling quality (Mckendry et al., 1995), especially under environments favorable for the development of leaf spots or under intensive management such as irrigation (Duczek and Jones-Flory, 1994) and high N fertilizer rates (Howard, et al., 1994). In the past decade there has been an increase in the incidence of leaf spotting diseases of wheat in southern Saskatchewan, Canada. These are attributed mainly to Pyrenophora tritici-repentis (tan spot), Septoria nodorum and S. tritici (septoria leaf blotch complex) and all current spring wheat cultivars are susceptible to this disease complex - 333 - (Fernandez, et al., 1996; Fernandez, et al., 1998). Consequently there is increased pressure on producers to chemically control diseases that might affect yield and quality. The magnitude of the impact of leaf spots on grain yield and quality of wheat cultivars grown on dryland in this area, however, is not known. Research on these issues is therefore necessary to provide informed guidelines for use by producers. The objective of this study was to determine the effect of leaf spots on grain yield, kernel weight, test weight and protein concentration of spring common (T. aestivum L.) and durum (T. turgidum L. var durum) wheat in southern Saskatchewan.
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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 | 0.001 |
| 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) | 0.001 | 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".