As others reached for cups and pastries during a coffee break at a canola workshop in Brandon, Murray Hartman reached for a petri dish containing canola seeds to make a point.
Hartman, an Alberta Agriculture oilseed specialist, held up the small, round container filled with blue canola seeds and a hand-written label of 7.5 grams.
If a grower receives a hybrid canola seed with a 1,000 kernel weight of 7.5 gram, that number cannot be ignored.
“It often comes on the bag. But when you’re ordering the seed ,you don’t know what the 1,000 kernel weight is till you get it,” said Hartman, who spoke at CanoLAB, a two day Canola Council of Canada and Manitoba Canola Growers workshop held mid-March in Brandon.
Read Also
Canadian crop outlook has improved since January says FCC
Canadian farmers’ overall new crop outlook has improved since the beginning of the year, says Farm Credit Canada.
“If you get something like seven (grams per 1,000 kernels), it’s a wow.”
Hartman said the 1,000 kernel weight of canola seed can range from three to 7.5 grams. Most hybrids are in the four to five range, but 1,000 kernel weights at the high end of the range can have a significant impact on plant density.
“I think the biggest thing that affects plant population and seeding rates, in particular, is the 1,000 kernel weight. It can often get overlooked,” said Laryssa Grenkow, research manager with the Western Applied Research Corp., a producer organization that conducts agricultural research at Scott, Sask.
“A large seed … (is) seven to eight grams per 1000 kernels.”
Grenkow, who also spoke at CanoLAB, said field experiments have shown that larger canola seeds are more vigorous and improve emergence 10 percent compared to smaller seed.
However, canola with a 1,000 kernel weight of 7.5 g has nearly half as many seeds as a 4.0 g 1000 kernel weight. A 10 percent increase in emergence doesn’t compensate for significantly fewer seeds.
“You’re getting half the seeds and you’re only getting 10 percent more emergence?” Hartman said.
“Now, I’m (at) 40 percent less plants established.”
Grenkow agreed, saying bigger seed and larger seedlings don’t necessarily “translate into higher yield potential,” which is why seeding rate is more critical than seed size.
Hartman said variety has an impact on seed size but the most significant factor is the growing conditions in southern Alberta, where 90 to 95 percent of hybrid canola seed is produced.
“If it’s optimal conditions, you’ll get a larger seed size.”
If a hybrid seed has a 1,000 kernel weight of four to five grams, Hartman said the seed size wouldn’t affect seeding rates.
If it’s six or seven grams, adjustments are required at seeding time.
“Increase the seeding rate to get the same amount of seeds per sq. foot,” he said.
“If I don’t want to spend the money on that, maybe look more carefully at the other things: seed shallower, slow down … maybe plant mid-May versus the last week of April, all the things that will improve your emergence percentage.”
Grenkow said growers should consider three factors when selecting a seeding rate: 1,000 kernel weight, expected seedling survival and a target plant population.
The Canola Council of Canada website provides a seeding rate formula to accommodate for seed size:
Seeding Rate = (9.6 x desired plant density (per sq. foot) x 1,000 kernel weight, grams) / estimated seed survival (percentage)
As an example: if the 1,000 kernel weight is 4 grams, desired plant population is eight plants per sq. foot and estimated seed survival is 50 percent, the seeding rate should be 6.1 pounds per acre.
(9.6 x 8 x 4 grams) / 50 = 6.1 lb./acre
If the 1,000 kernel weight is 6.5g: (9.6 x 8 x 6.5) / 50 = 10 lb./acre
