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International Seed Testing Association
International Seed Testing Association
Richtiarkade 18
8304 Wallisellen, CH
+41 44 838 60 00
International Seed Testing Association

Standard Proficiency Test

Standard Programme Plan

The ISTA Proficiency Test Committee defines the ISTA Standard PT Programme Plan which is valid for a three year period between two ISTA Congresses. They select species which are listed in the ISTA Rules Table 2C. Chosen species belong as per their size and germination type to the ISTA defined crop groups: grasses, cereals, small legumes, pulses, other agricultural species, vegetables, forest, and flowers. (See: ISTA Crop Groups).

Plan and procedure

Round and Results

Schedule and Ratings

Samples are provided to the participants three times per year:

  • 1st of April
  • 1st of August
  • 1st of December

Each round includes three samples for each test, as defined by the Programme Plan.
e.g. purity, other seed determination, germination, moisture, viability or vigour tests.

The duration of each round is three months when the results are reported to the ISTA Secretariat. An A, B, C rating principle is applied and the evaluated results are reported back to the participants in several steps:

1. Heterogeneity results         

The heterogeneity test results are published at the ISTA website immediately after the results reporting deadline is reached. Heterogeneity results are not the expected results, but a good indication of the quality of seed lots at the time of sample preparation. They also include the images of the other seed spiked in the PT round.

2. Preliminary results

The preliminary results are individual results for each laboratory,they are ‘personal’ results calculated for each participant.

3. Final results

The final results are calculated approximately one month after the preliminary results. Generally, there are no differences between preliminary and final results. Next to the individual result of the particular round, the final results include also an overall result of all rounds the laboratory participated in. These results are also graphically presented to show the possible trends in the laboratory performance (whether the participant overestimate or underestimate when testing, or is it in the middle with the results).

4. Summary results

Summary results present and overview of the PT round, for example:

  • How did accredited participants perform in comparison with the non-accredited laboratories or
  • Which testing method was the most applied in that PT round

For understanding the Rating System, Evaluation, and Reporting results refer to the following document: 

ISTA Standard Proficiency Test

Please visit the Technical Committee page to access Proficiency Test Documents and further insights:

Proficiency Test Committee

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