Seed Health of commercially produced seed depends on many factors. The most important ones are the starting material - seeds or plants used to produce the new seed generation, the environment (open field or greenhouse production, climate conditions), water quality, skills and (regular) training of personnel, crop monitoring and testing, and at the end, for the harvested seed, testing.
A well-functioning quality management system supports all aspects of healthy seed production, like inspection of the starting material (seed or plants), tools for crop management and harvest. All these aspects should be regarded parts of the seed production process. This process, described in the Quality Management System (QMS), provide structure and guidance. It allows for documenting and implementing improvements and it provides the framework for measuring performance of the seed production.
For seed health, a well-functioning QMS is vital, because testing seed is by definition restricted: seed health tests are based on samples taken from the seed batch. With the samples chances and statistics come into the equation. Even if large samples are tested, for instance 30.000 seeds, always a minute risk remains that a low-level of infections will not be detected. To minimize this risk, the seed industry determines minimum sample sizes per plant/pathogen combination, that provide sufficient proof that, even if a low level of infection is present, such a low-level infection would not have a negative impact on the production of the crop grown from such seed. Impartial certifications by certifying bodies strengthen seed production, the internal test laboratories of the seed companies and the seed companies as a whole. Inspections, sampling and testing by National Inspection Services and National Plant Protection Organizations complete the picture.
So, why is that QMS so important? Because it provides a solid knowledge base that assures that the production was 'clean', without threatening infections, from start to harvest. If the production was clean, the resulting seed should be clean... Testing provides additional proof that the seed indeed meets the defined criteria for seed health (and also for germination, purity and trueness-to-type).