Frost damage occurs in cereal seed when the cell membrane structures have been ruptured. The stage of the plants maturity is crucial because if the seed is still at the “filling stage” or the “milky stage” where the seed is high in moisture the damage will be more severe.
Frost damaged grain is white or grey in colour, smaller, often shriveled with a wrinkled texture. Oats may be black and lack the usual glossy coating. Often no symptoms are apparent and the damage is only identified through a germination or vigour test.
What Does Frost Damage Look Like?
This type of damage is identified by seedling abnormalities displayed during a germination test.
The small plants will appear to be grainy, with little or no leaf development. Often the coleoptiles will be empty; they may also appear shriveled, or twisted, unlike a normal seedling, which is strong and straight. Severe damage will completely kill the seed; the dead seed in a germination test is black and very soft.
Frost damaged seed that is dead is very distinct from any other form of dead seed, such as heated seed. Frost damage will be reported because it has a detrimental effect on the long-term storage of the seed and affects the essential structures of the seed, especially the embryo. As well, frost damage is not static and will continue to deteriorate seed quality as time goes by. It is difficult to determine how long germination may remain stable because frost damaged seed is especially sensitive to temperature fluctuations during storage. For more information, please refer to Barley Production in Alberta: Crop Damage at: http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/crop1224
What Can I do?
I think it is safe to say that a seed with frost damage that is making grade at this time of the year should, with good storage, maintain a reasonable germination. If the report indicates a result lower than an 85% germination, with all of the remaining seed being dead or abnormal due to frost, then one should consider finding new seed.
Frost damaged seed cannot be enhanced or remedied with seed treatments, the damage has already manifested itself and it would be futile to invest in a seed protectant in this case.
We are experiencing severe frost damage on oats, as one would expect, because oats are a later maturing crop and are more susceptible to frost. The symptoms are very clear and we have had samples that have 0% viability. Wheat is a close second for frost damage and barley is third. On the bright side, not all cereals are affected and there are many samples that are stellar, depending on the region where they were produced.
Please pay close attention to your reports of analysis and please be sure to phone one of our seed analysts if you have questions about your seed quality.