April 16, 2003

Research is confirming a trend first identified in field experiments at the Merredin Research Station in 2001, when larger canola seeds delivered up to 54 per cent higher yields than their smaller counterparts.

Supported by growers and the Federal Government through the Grains Research and Development Corporation (GRDC), Glen Riethmuller of the Department of Agriculture recently tested seeds of different sizes for their establishment and subsequent yield performance under specific conditions.

"We planted seeds of greater than five grams per 1000 seeds and smaller seeds of

3 g/1000 at three sowing depths at Erregulla Plains, Mingenew," Mr Riethmuller said.

"With soil moisture marginal, we were interested to find that larger seeds established more than twice as many plants (53 per m² total) at 60 mm depth. Growers could sow deeper with large seeds to chase moisture in dry conditions on sandplain soils."

After a stronger start, large seeds produced 20 per cent higher yields at 60 mm depth and also outperformed smaller seeds at 40 mm. Increasing the seeding rate for small seeds failed to compensate for the establishment discrepancy and reduced eventual yields when tested at 40 mm seeding depth.

"Except for small seeds at 60 mm, a good oil content of about 45 per cent was harvested from all trial plots," Mr Riethmuller said.

As part of the GRDC project, simultaneous experiments at Mingenew and Mullewa found that seeding with narrow points and press wheels established plant densities 47 per cent higher than with triple discs and 59 per cent higher than with full cut and rotary harrows. Stubble removal had no effect on the canola establishment or yield.

"As seeding approaches, this information arms canola growers with valuable new knowledge," Mr Riethmuller said.