Checking seed quality
Visual checking, cut-testing or x-ray tests at the seed cleaning stage will not determine for certain whether seeds are viable and therefore likely to be able to germinate. However, such tests can provide important clues to the overall quality of the seeds.
X-raying a sample of seeds can show how many are empty or damaged (Image: RBG Kew)
For example, we can determine the proportion of empty or incompletely-formed seeds and those that have been damaged by insects. Seeds that are empty or where insects have damaged key parts of the seed embryo are ‘incompetent’ and will not germinate.
Tests are carried out on a small sub-sample of the main collection either by X-ray analysis or by means of a cut-test. If either method reveals a high proportion of ‘incompetent’ seeds then it may be possible to reduce the proportion by re-cleaning.
If ‘incompetent’ seeds cannot be removed from the collection, the proportion of healthy-looking seeds is recorded to help interpret the results of subsequent germination tests. For instance, if there are 50% incompetent seeds in a seed collection yet 50% germinate, then 100% of the competent seeds germinated. The MSBP approach to recording germination results ignores the incompetent seeds when calculating germination and viability. In the commercial testing of crop seeds the proportions of incompetent seeds are usually included in calculations so that growers can more easily work out how many seeds need to be sown.
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