Germination tests are conducted for a prescribed time period under laboratory conditions that assure optimum moisture, temperature and light. Unfortunately, these conditions are seldom encountered in the field, and field emergence may be overestimated by standard germination tests. Seed lots that have low germination also are less vigorous due to seed deterioration. As seeds deteriorate, loss of vigor precedes loss of viability, so seeds with low germination usually will be less vigorous. Hence, in seed lots with poor germination, those seeds that do germinate often produce weaker seedlings with reduced yield potential.
Varietal purity indicates genetic purity of the seed.
This factor is extremely important in obtaining pure stands of a specific variety. Varietal mixtures can cause uneven maturity, lower yield potential, increased susceptibility to disease and insect pests, and be less adapted to specific environmental conditions. Varietal mixtures are difficult to detect through examination of the physical characteristics of the seed. Seed certification programs and many seed companies rely heavily on inspection of the seed production field to assure varietal purity. When choosing seed stocks, select those that are labeled by variety name, preferably certified seed.