Background
There is a strong imperative to sow cereal crops early in Western Australia. This often means sowing into drier than ideal seedbeds.
Sometimes the soil surface is dry but there is moisture remaining from summer rain in soil deeper than the normal seeding depth.
Deeper than normal sowing to place seed on this moisture can result in earlier crop establishment, but some wheat cultivars will emerge from depth better than others.
Among other factors, the ability to emerge from deep sowing is related to coleoptile length and seed size.
There is also evidence for variation in tolerance to early water deficit, which may also be involved.
Aim
To test to ability of different wheat cultivars to emerge from deep sowing onto moist soil under a dry surface.
Trial details
| Property | DAFWA Mullewa Research Annex, Ardingly South Rd, Mullewa |
|---|---|
| Soil type | Red loam |
| Crop / variety | Wheat |
| Treatments | Wheat cultivars Cobra, Corack, Emu Rock, Estoc, Mace, Magenta and Wyalkatchem with small and large seed of each variety |
| Replicates | Four |
| Sowing date | 5 August 2014 |
| Seeding rate | Calculated to give 120 plants/m2 |
Results
When this trial was sown, volumetric soil moisture in the top 50mm was less than 5% with matric potential of -8.1 megapascals (MPa) and from 50-80mm was about 9% with matric potential -0.3MPa.
Wheat was sown at 80mm depth. Emergence on 14 days after sowing is shown in Table 2.
| Cultivar | Large seed density (plants/m2) | Small seed density (plants/m2) |
|---|---|---|
| Cobra | 25.1 | 13.6 |
| Corack | 28.6 | 18.3 |
| Emu Rock | 28.4 | 12.8 |
| Estoc | 31.7 | 14.8 |
| Mace | 31.2 | 28.0 |
| Magenta | 34.6 | 21.1 |
| Wyalkatchem | 16.1 | 19.8 |
Comments
Variety can have a large effect on emergence from depth but seed size is also very important. Further measurements on this trial will clarify this.
Acknowledgements
This trial is part of the Grains Research and Development Corporation funded project DAW00218 Wheat agronomy - building system profitability in the Western Region.