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Pulse dormancy a big issue after last year’s wet conditions

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The last thing you want is sleepy seeds.

Seeds are supposed to sprout when soil temperatures and moisture conditions are right, but some batches of seeds lay dormant even when Mother Nature is telling them to get growing.

But there are ways to discourage dormancy, Sarah Foster, senior seed analyst with 20/20 seed labs, told attendees at FarmTech.

“Take advantage when the weather gets below -15 C,” said Foster. “Start aerating your bins and that will make a huge difference on the quality of your lot. Seed needs to get into a resting stage where its respiration lot is dropped down very, very low and it can mature naturally in the bin.”

Hard seed is a form of dormancy seen in peas, beans, lentils and clovers, and all of the samples that Foster has seen from southern Alberta this year are showing hard seed in their germination profile.

“I’ve never seen it in Canada to the extent that we’ve seen it this season,” she said.

Hard seed is impermeable to water, which means its seed coat hasn’t developed properly due to a lack of nitrogen. The heavy rains in southern Alberta may have caused nitrogen leaching which resulted in hard seed.

“The levels aren’t so high that they’re affecting the grade, but it’s something that we can tell you based on your germination results,” she said.

There are only three seed tests accredited by the Canadian Food Inspection Agency (CFIA) — germination, purity and smut. Vigour is not an accredited test. Germination tests show what seed is capable of doing under favourable field conditions and all accredited labs use the same CFIA-approved method, said Foster.

“Unfortunately, the germination test doesn’t give us the overall picture,” she said. “It is one of the blocks in the quality building profile that I’m going to talk about. It isn’t the most significant, but it is the most recognized.”

By law, seed labs are required to test 200 seeds per batch for a test to be considered legitimate. If signs of dormancy are seen, the seeds are placed in a three-day pre-chill to bring their respiration rate down. The seed is then shocked to grow in a 20 C temperature. If the dormancy is too strong, the analysts use potassium nitrate or giberellic acid, both of which are commonly used in the industry.

“The problem with that is that we are giving the seed an enhanced germination,” said Foster. “But we do know that this is the potential of the germination.”

The process breaks the dormancy by giving the seed the chemical or enzyme that it’s lacking. The ideal germination rate for good-quality seed is 95 per cent. The minimum standard in Canada is 85 per cent.

Another issue is frost damage, which occurs when seed hasn’t fully matured. The cell membranes and tissues become ruptured and permanently damaged.

“When you test seed in the fall right after it’s harvested, we can only pick up a small percentage of frost damage,” said Foster. “The only way we can give you the overall picture is to put it into a vigour test.

“Germination in the presence of frost is not enough. You need to be testing at least two or three times more to make sure the germination is still viable.”

Once the frost has damaged the seed, it continues to deteriorate the seed lot and germination ability is lost over time.

Foster reminded her audience that glyphosate-based products cannot be used on seeds intended for seed purposes.

“If the seed or the plant is sprayed when the moisture is at 20 per cent or more, severe damage occurs after spraying,” she said.

The roots and shoots develop, but the seed also develops significant abnormalities that cannot be picked out by an untrained eye. Good roots have hairs that anchor them in the soil. When there is chemical damage, these hairs do not develop properly and will compromise the plant later on.

About the author

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Alexis Kienlen

Alexis Kienlen lives in Edmonton and has been writing for Alberta Farmer since 2008. Originally from Saskatoon, Alexis is also the author of two collections of poetry, a biography, and a novel called "Mad Cow."

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