Hybrid canola a resowing winner

Department of Agriculture and Food WA (DAFWA) senior research officer Mark Seymour said hybrid canola varieties could compensate grain yield at plant densities as low as five per square metre (sq m).

“Canola is such an adaptable plant, you can really manipulate it into making big changes.

“For instance, if you have low plant densities, the plants will generally spread to cover the gap, and there is more yield out of secondary branches than you get from other crops.

“In many cases it might not be worthwhile resowing, especially if you are using hybrid seed, which is more expensive.

“The results show an early sown, low density crop still beats later sown crops at higher densities.”

However, Mr Seymour said there could be rotational reasons to establish a thicker plant canopy.

“Weeds could be a problem in canola crops that have low plant numbers as a result of poor crop establishment,” he said.

In terms of yield, Mr Seymour said his research had showed plant numbers had to be extremely low to make resowing worthwhile.

“If you are debating whether or not to resow, the answer is nearly always going to be not to do it.”

He said canola was the most visible victim of a ‘false break’, where it had sufficient rain to germinate but not to go on growing.

“Canola is often the first crop sown each autumn, but as the seed is small it is best suited to shallow seeding, making it susceptible to drying soil conditions,” he said.

The trials assessed sowing canola before or at the break of the season at plant densities of five, 10, 15 and 30 plants per sq m, compared with plots resown at 30 plants/sq m over the top of five and 10 plants/sq m and plots sown normally (not resown) at later dates at five to 60 plants/sq m.

“As expected, the April sown plots out-yielded plots sown in May, at every comparable plant density,” Mr Seymour said.

“In addition, April plots that had only five to 10 plants/sq m produced equal or higher yields than later sown plots at higher densities.”