Prairie Giants Crop Report - Calculating Cereal Seeding Rates & Interpreting Seed Tests

The Prairie Giants Crop Report

Field observations at your fingertips

January 13, 2024

Taylor Kurtenbach

Calculating Cereal Seeding Rates & Interpreting Seed Tests

There are many reasons why we promote using certified seed – guaranteed quality, free of weed seeds, and access to the newest genetics/traits. With that being said, we understand that using certified seed on all your acres every year is not always possible. When using common seed, we always recommend doing a seed test prior to seeding to ensure quality and determine seeding rates. Doing this ensures your crop gets the best possible start!

Interpreting Seed Tests

Germination – the percentage of seeds that grow in optimal conditions. This is typically what we will use when calculating seeding rates.

Vigour – the percentage of seeds that grow in stressful conditions, like cool temperatures. Also known as a cold stress test.

1000 Kernel Weight (TKW) – weight in grams of 1000 seeds.

Disease Testing – can screen for multiple seed borne diseases such as fusarium, smut, etc.

Germination and vigour may be different percentages. This can be due to the pathogens (disease causing organisms) present on the seed and the conditions they thrive in. For example, Rhizoctonia is more common in cool conditions and would therefore have an impact on vigour. On the flip side, Fusarium is more common in warm conditions and would have more of an influence on germination. So, if a seed was infected with fusarium, it would be more likely that germination percentage would be lower than vigour. An application of a registered seed treatment can help alleviate this by controlling, or suppressing, these diseases. Read more here.

Another factor that may impact germination is an application of glyphosate at pre-harvest timing. Germination can possibly be reduced. This is why we don’t recommend using seed sprayed with glyphosate. If you plan on using it anyways, we recommend testing for germination twice – once early in the winter to determine if the seed is good quality and right before seeding as glyphosate can affect germination the longer the seed is dormant.

When testing your seed, we recommend testing for germination and TKW as these are two key values used to determine seeding rates.

Calculating Seeding Rates

There are calculators available online to determine seeding rates. Check out FP Genetics seeding rate calculator here:

https://www.fpgenetics.ca/why-choose-certified-seed/

By inputting a few values (desired plant density, TKW, germination rate and emergence mortality), the optimal seeding rate will be calculated. Calculating your seeding rate using a calculator should be done whether using certified or farm saved seed.

Ideal plant densities for each crop are:

Wheat: 28 – 35 plants per square foot

Barley: 25 – 30 plants per square foot

Oats: 20 – 28 plants per square foot

Peas: 7 – 9 plants per square foot

We prefer the higher end of the scale, as it can help the crop withstand stressors better and helps to cover the ground quicker.

Typically for emergence mortality we will use a standard value of 10%.

By adjusting your seeding rate based on the seed lot’s specs instead of the standard 2 bushel / acre rate, you can get the most value out of your seed investment. Reach out to a Prairie Giants agronomist to chat about certified seed, getting your seed sent away or determining seeding rates!