LETHBRIDGE – Seeding rates can have a dramatic effect on the success of cereal crops grown in Western Canada.
At the Agronomy Update conference held earlier this year in Lethbridge, Brian Beres presented research results from his own studies as well as related study results from other researchers.
Beres, a research scientist with Agriculture Canada in Lethbridge, recently started a sawfly study that will attempt to update seeding rate recommendations for southern Alberta. He’s especially interested in new spring wheat varieties registered in the last few years.
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“My levels were 150, 250, 350 and 450 seeds per metre squared, on AC Avonlea durum, AC Lillian, which is sawfly resistant and CDC Go, which is a short statured high yielding hollow stemmed variety,” Beres said.
“With Go we had a positive yield response through the 450 seeding rate. We were topping out with Avonlea at the 350 rate.”
Beres noted that to convert seeds per metre squared to seeds per square foot, divide by 10.
While it’s only one year of data, Beres said higher seeding rates might be something to consider.
“If you aren’t seeding in the range of 350 seeds per metre squared with durum or red spring wheat, you may want to start experimenting with that. We were observing positive responses through 350 and even up to 450.”
Beres said a recently completed study on malting barley by Alberta Agriculture researcher Ross McKenzie in Lethbridge looked at fertility and seeding dates and rates using AC Metcalf as the two-row variety and Excel as the six-row variety. McKenzie used three seeding rates and three seeding dates: early; early plus 10 days and early plus 20 days.
There was no significant increase in yield beyond the 250 seed per metre squared rate. Beres said the study showed no detrimental effect to protein levels, but concerns arose with seed plumpness as the population increased beyond the 250 seed rate.
“We’re observing a higher percentage of thins as we move up into that 250 to 300 rate, to an unacceptable level at the 350 rate,” Beres said.
“What Ross found was that 150 to 200 plants per metre squared, or 15 to 20 plants per sq. foot, for malt quality, was best. You could increase that 30 to 50 percent if you’re targeting feed barley. But malt barley is tricky to work with and you have to be careful with plant densities.”
Beres said phosphorus, potassium and sulfer did not affect malting yield or quality in this study and higher nitrogen rates generally decreased kernel size.
Another project headed by McKenzie looked at seeding rates of winter wheat and winter triticale, comparing hoe versus disc seed opener and early versus late seeding dates.
The plant density targets were 150, 200, 250, 300 and 350 plants per sq. metre, using AC Bellatrix winter wheat and Bobcat winter triticale.
With winter wheat, the hoe opener produced a plant density of 183 plants per sq. metre compared to 201 for the disc opener, but the hoe opener yielded better, at 6,403 kilograms per hectare compared to 6,261 kg per ha.
“Our ideal seeding date in our area is the first 10 days of September. In the study, this provided a significant advantage compared to a later seed date,” said Beres.
The September yield was 6,825 kg per ha, while the October yield was 5,839 kg per ha.
“For seeding rates, we observed a positive response through all the seed rates, right through to the 350 plants per sq. metre.”
Winter triticale had a similar story. There was a yield advantage with the hoe type opener compared to the disc and a positive response to an early compared to late seeding date. As well, there was a positive yield response as seeding rates increased.
Beres and other southern Alberta researchers initiated a separate three-factor experiment, looking at how some of the newer winter wheat varieties performed.
“Radiant and Osprey are milling type winter wheats, Falcon is a feed type and Ptarmigan is a soft white winter class. Seeding rates we chose were 300, 450 and 600 seeds per sq. metre,” he said.
Beres said using the kernel weight of CDC Falcon, 450 would be about 2.3 bushels per acre for a seeding rate. Weed control options included only a fall 2,4-D application and a fall 2,4-D plus spring herbicide application.
“We didn’t see a significant increase in grain yield as we increased our seeding rate, but there are a couple of things to keep in mind. We didn’t have a fertility factor, so there could have been nutrient deficiencies beginning as we increased the plant populations,” he said.
“Dockage declined as seeding rates increased, so seeding rates don’t just relate to advantages in terms of yield. In the spring, at the minimum I’d like to see 200 plant per sq. metre or 20 plants per sq. foot. We were just getting there with the 300 seed rate, so we gain a lot of insurance by moving to the middle seed rate of 450.”
As Beres increased the winter wheat seeding rates, he significantly reduced the biomass and competitiveness of the weeds, and significantly increased the competitiveness of the winter wheat crop, which is already competitive.
“But we can still gain an advantage if we increase seed rates to an ideal competitive rate.”
Beres said the lowest seed rate provided significant light penetration through the early plant canopy, which provides an opportunity for weeds. The canopy was virtually closed by the time he reached the 600 seed rate.
Beres said this study concluded that planting winter wheat and winter triticale at 450 seeds per sq. metre would result in optimum plant densities and grain yields.
