- Grain yields of most canola varieties at Salmon Gums started to plateau at ~20 plants per square metre (plants/m²).
- Taking into account the costs of increasing plant density we calculated the economic optimum for higher cost seed types such as Roundup Ready (RR) and hybrid Triazine Tolerant (TT) to be 25 plants/m² or less.
- Hyola 404RR had the flattest response indicating its yields were less affected by lower plant densities.
Canola is now being grown in low rainfall areas. Primarily growers choose open-pollinated TT varieties. However breeding companies are favouring the development of hybrids in order to pay for breeding services. Hybrids provide growers with more vigorous seedlings, comparatively better plant establishment and generally higher yields. However growers have to purchase new seed of hybrid varieties every year in order to get these potential yield benefits. Seed for hybrid canola is 25 times more expensive than the seed of open-pollinated canola. Inevitably if growers decide to use hybrids they may wish to minimise seed costs by sowing at low densities.
To investigate the plant density response to yield and oil content of TT and RR hybrid canola in comparison with open-pollinated canola.