A re-assessment of the comparison of tetrazolium viability testing and germination testing

A re-assessment is made of the definition of viability and the definition o f germination. Both quality traits clearly describe specific and different seed properties. The differences are shown up by considering test results. The term viability relates to the potential for a resting seed to produce a normal seedling, by definition it does not need actual realisation in a ge rmination test but can be approached by predictive methods. Recommendations are made for the revision of the wording of the viability testing prescrip tions in the ISTA Rules in order to meet the viability definition.