Weathering & Seed Quality

Securing seed supply requires farmers to be informed to make good decisions and to manage potential risks. As an old saying goes “Quality in equals quality out”, so farmers must place emphasis on planting high quality seed.  Regardless of seed source, it is recommended that growers obtain as much information as possible on the seed lot in order to make informed decisions. It only makes sense as there is only one opportunity to set the crop up for success.

In 2014, poor harvest conditions led to downgrading of cereal grains due to weathering factors such as sprouting and mildew. Questions in regards to the potential of downgraded wheat for seed supplies has been raised.  First, what is sprout damage and mildew?

Sprout Damage.  Sprout damage is pre-harvest germination. Germination begins when mature kernels absorb water and generate enzymes that break down stored starch and protein in the endosperm. The enzymes release sugars from starch and amino acids from proteins which nourish the growing embryo.  One of these enzymes is called alpha-amylase which is the enzyme measured when conducting the Falling Number test.   Keep in mind though you don’t need to see a visibly sprouted seed for those germination processes to have started within the seed.

Mildew.  Mildew is indicated by grey discolouration on the brush or distal end of the kernel.  Mildew is associated with weathering and sprout damage. It is saprophytic or non-pathogenic.

So if you have weathered seed and are wondering if you should use this seed for replanting next year, some tips are:

  • Although visual assessments can be a good starting place in selecting quality seed, testing is critical since it is the most accurate way to determine the ability of seed to germinate, and additionally the presence of disease and vigour.  A grade and protein assessment at the elevator or by the Canadian Grain Commission is not a verification of seed quality for planting.
  • Have tests conducted at an accredited lab. Home germination tests do not count!  Take a representative sample, after cleaning the seed lot.  It would be a good idea to phone the accredited lab you are submitting samples to so you can follow their procedures for sampling and submitting.
  • Have samples tested as early as possible so you know what you are working with.
  • However, if you do test early and results come back positive that the seed lot would be suitable for seed, I would encourage re-testing in early March. Germination can decrease in the bin over the winter, especially if the seed was immature, sprouted or otherwise damaged at harvest.  Therefore, it would be a good investment to test again in early March – that would allow you to have results back by late March, still giving you time to react and source new seed if the tests come back not as positive.

Finally, remember that best seeding practices — adequate seed bed preparation, proper seeding depth, using a seeding rate based on germination and thousand kernel weight to achieve your target plant stand, and use of seed treatments if necessary — will not rescue a poor seed lot!

Submitted by: Pam de Rocquigny, Provincial Cereal Crops Specialist, MAFRD

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