SWI 132.1.1 Seed Program
Specific Work Instruction
Official Seed Sampling

10.0 Lot Homogeneity

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When the seed lot is being sampled for any purpose (including export certification, marketplace surveillance, complaint/compliance sampling, investigations, etc.) the primary samples representative of the seed lot must be checked for uniformity. Paragraph 7(1)(a.1) of the Seeds Regulations requires that the seed be appropriately mixed, blended and processed so that it is as uniform as practicable. Indicators of seed lot heterogeneity may be:

  1. different types or sizes of containers;
  2. different labels or labelling information;
  3. different types of seals.

When blended seed lots are presented for sampling, there should be documentation regarding the origin and about the mixing and blending of the seed lots. Upon request from the sampler, the owner of the seed lot is required to provide full information regarding the bulking and mixing of each seed lot sampled. If the establishment cannot provide appropriate documentation to support the homogeneity of the seed lot, sampling should be refused.

The contents of each trier or handful etc. are known as a primary sample. During sampling, the sampler must keep each individual primary sample separate from the previously drawn primary sample. The sampler must assess the primary sample for uniformity before combining the primary sample with other primary samples drawn. Uniform primary samples are combined to produce the composite sample.

Uniformity can be assessed by:

  1. verifying that the species is the kind presented for sampling;
  2. verifying the colour, size and shape of the seed are uniform within and between each primary sample;
  3. the amount of chaffy material is uniform within and between each primary sample;
  4. the presence of visible impurities appears uniform throughout the seed lot.

If the primary samples are not uniform:

  1. the sampler should refuse to submit samples for export certification when there is definite evidence that the seed lot is not reasonably uniform. The sampler must refuse to sample the seed lot, until appropriate corrective action has been taken;
  2. when sampling for other official purposes (e.g., marketplace surveillance), the sampler must submit the sample and note the evidence of heterogeneity on the SSF (Appendix V). The seed sampler should take steps to determine the source of the heterogeneity and take appropriate compliance and/or enforcement actions.
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