Hybrid seed often weighs 5 grams or more per 1,000 seeds. If a grower seeds a 5-gram hybrid at 4 lb./ac. (1,800 grams per acre), that works out to 8 seeds per square foot. At 60% seedling survival, the stand is only 5 plants per square foot.
The ideal target is 10 plants per square foot, which provides some buffer for mortality. Seeding large seed at 4 lb./ac. will not achieve desired plant stands. Higher seeding rates are required.
Studies have shown that larger seeds will have better germination, especially in cooler soils, but once seeds get above 4-5 grams per 1,000, this seed size benefit may plateau. Seed weighing 5.5 grams may not have an advantage over seed weighing 5 grams, for example.
Stands below 5 plants per square foot can still produce reasonable yields under ideal conditions, but are much more vulnerable to later stresses that limit the ability of the plants to compensate through increased branching and pod production. There is no buffer against further plant losses due to weather, diseases and insects. Also, canola that branches out to compensate for a thin stand will mature later, which increases the risk of yield loss and high green counts due to fall frost.