Vigour tests don’t give a complete picture of the viability of the seed, are not accredited in Canada and can vary by lab.
So it’s important growers understand the type of vigour test used by their lab, says Sarah Foster, senior seed analyst at 20/20 seed labs.
At least seven different vigour methods are commonly used, and each can yield different results. Cereals are usually heat tested at 5 C. Another method, which can be used on canola, stresses the seed by exposing it to high humidity and high heat for 48 hours. If the seed passes through without incident, then its vigour is ensured.
Foster grows plants from seed, and checks to see the seedlings are healthy and uniform, as uniformity in seedlings is key to a well-established plant stand.
“The beauty with this particular method is that it mimics and simulates what happens in the Canadian Prairies in the spring,” she said. “The most recognized test is this particular test that stresses it by temperature.”
By contrast, vigour testing done using temperatures above 5 C puts the seed back into optimum conditions. Producers getting vigour tests should ask if their labs are doing a “cold” or a “cool” test for vigour. If vigour isn’t present in the seed, producers need to realize their seed may present a risk.
“You wouldn’t go in at 5 C. You would wait until the temperature went up a bit. But you wouldn’t use a test that had been done at 8 C or 9 C, because it doesn’t tell you the full picture,” Foster said.
Producers must also check the health of their seed by having them tested for diseases that might be present. Producers should ask for a fungal screen when they are having their seed tested to ensure seeds are free from disease, Foster said.