Longmont, Colorado, USA
September 2009
Source: Eurofins STA newsletter
by Linda Barbosa
A representative sample is the fundamental building block of an accurate test. No seed lot is perfectly homogeneous and thus a sample from that lot which is to be tested for germination or seed health must be representative of the lot. In order to obtain such a representative sample, the entire lot must be sampled in a reasonable manner. Rules have been developed by the Association of Official Seed Analysts (AOSA) to accomplish this purpose. These Rules state that to secure a representative sample equal portions shall be taken from evenly distributed parts of a lot. Most seed should be sampled using a trier (a specialized seed sampling device) that is approved by AOSA and AASCO, Association of American Seed Control Officials.
The Rules also state that when a lot is composed of one to six bags sample each bag and take a total of at least five core samples. Larger lots will require more sampling. When seed is packaged in small containers several entire containers shall be combined to create a representative sample. The AASCO Seed Sampling handbook contains detailed instructions on the number of samples to be taken based on the lot size and how to arrive at a representative composite sample
The disclaimer at the bottom of certificates of analysis issued by Eurofins STA Labs states; “This analysis is based only on the sample received and does not represent guarantee of the lot or sample from which it is taken. The representative nature of the sample is the responsibility of the sender.”
For vegetable germination testing a minimum of 400 seeds is required. For purity and noxious weed examinations a minimum of 25,000 seeds is required. Various other crops require a larger submitted sample. If the sample drawn is larger than required it shall be thoroughly mixed before it is divided to the desired size.
Sample sizes for seed pathology tests vary significantly so please contact Eurofins STA staff for the recommended size of samples to be submitted.
This article is not intended as complete instruction in seed sampling. See the AOSA rules or AASCO Seed Sampling Handbook for complete methods.
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