Why accurate sampling is essential
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Why accurate sampling is essential
Careful sampling of a seed lot is essential if the seed analysis results are to accurately reflect the quality of the whole seed lot.
Seed is traded on Australian and most international markets on the basis of tests conducted according to the methods and requirements of the International Seed Testing Association (ISTA). Extensive research has shown that a major source of variation in seed testing results is attributable to incorrect sampling. Thus accuracy in sampling is of fundamental importance, starting from drawing the primary sample(s) from the seed lot through to obtaining the working sample in the seed testing laboratory.
Seed sampling is a fundamental part of the ISTA International Rules for Seed Testing (ISTA Rules), which must be used to sample and test seed lots produced under the OECD and Australian Seed Certification Schemes and other seed quality assurance schemes in Australia.
The ISTA Rules provide standardised definitions and procedures to be used for evaluating seed, and should always be used for international and official transactions, where a high degree of accuracy and reproducibility is necessary. However, this practice should not be limited to such circumstances, but rather should be applied to all seed trade transactions within Australia.
The object of seed sampling is to obtain from a seed lot a representative sample of a size suitable for the required tests. How reliable those tests will be in determining the quality of a seed lot depends primarily on the accuracy with which the sample represents the lot and the accuracy and precision of the laboratory tests.
The sample of seed that can be tested in a laboratory is minute in comparison with the size of the seed lot from which it is drawn and intended to represent. It is therefore essential that the seed analysed is truly representative of the ‘quality’ of the seed lot from which it is drawn. The responsibility for drawing a truly representative sample rests with the seed sampler.
Training in seed sampling is provided by the ASA-authorised Certification Agencies and may be available from other sources. Samples which are to be tested for the issuance of ISTA International Seed Lot Certificates may only be drawn by samplers who have been authorised by an ISTA-accredited seed testing laboratory.