What is high quality seed? What is low quality seed? Why should farmers be concerned about the quality of seed they plant? Each of the above questions should be addressed by farm managers regardless of whether they use conventional-till, minimum-till or no-till operations.

Seed quality is judged be several attributes including: germination percentage, purity, freedom from disease, color, seed size or weight and vigor. In addition, certified seed is commonly associated with high quality seed.

Germination percentage is most universally used to judge seed quality because it is indicative of the potential stand expected from planting a specific seed lot. Further, several research trials have demonstrated seed germination percentage may be indicative of seed vigor and ultimate yield potential, particularly in spring planted crops. A durum drillbox survey, consisting of 274 samples, conducted by Spilde and Hafdahl (3) in eight North Dakota counties showed a positive relationship between grain yield and germination percentage, particularly under drought-stress conditions. In addition, these data demonstrations that grain yield increased from 39 bu/acre to 53 bu/acre, when stand establishment as a result of improved germination.

Freedom from seed-borne diseases is another reliable predictor of high quality seed. Manifestation of seed-borne diseases are reduced germination percentage and vigor. All seed lots contain some disease. However, the infection level can be reduced with the use of proper seed conditioning equipment and seed treatment. Spilde and Pingree (unpublished data) evaluated moderately infected HRSW seed samples, which indicated seed emergence in warm soil (68°C) increased 4% with the use of a length grader and gravity separator, as compared to the sole use of an air-screen separator. Application of seed treatment, improved seedling emergence an additional 10%.

Seed size and weight are two additional characteristics frequently associated with seedling emergence and field performance, particularly in spring-seeded crops. Numerous studies conducted in North Dakota and Canada have demonstrated improved crop performance of cereal grains when large-sized or heavy seed are planted. Spilde (2) reported medium and large barley seed sizes produced 4 and 6% greater grain yield than small seed. Similarly, grain yield of HRSW increased 5 and 7% when large seed was planted compared with medium and small seed, respectively. Increased seed test weight produced results as seed size. The influence of seed size also may be manifested on seedling vigor. Barley moisture levels have been significantly lower in grain produced from large or heavy seed than for light or small seed(1,2).

Seed vigor may be defined as, "The total of all properties of seed which determine the performance of the seed during germination and subsequent plant growth". The effect of vigor is typically manifested during germination resulting in faster emergence and early seedling growth stages. High seed vigor also may be manifested by reduced plant disease levels. The effect of seed vigor levels on final grain yield will be influenced substantially by the environment throughout the growth period. Grain yield and quality are generally improved with high vigor seed. However, the differences may not be large enough to be considered statistically significant.

Certified seed has germination and purity standards that are considered to be minimum for good quality seed. The economic advantages derived from planting certified seed are well documented. Spilde and Hafdahl (3) demonstrated that durum samples planted from certified seed sources produced 1.8 bushels/acre higher yield than uncertified samples when averaged over 1988 and 1989 production years. Assuming these data represent the seed planted throughout North Dakota, farmers in the state sacrificed $16 million in lost income when compared to what it would have been with 100% of the durum acreage planted with seed.