66 / SEEDWORLD.COM SEPTEMBER 2017 WHEN IT COMES to seed quality, customers want to know exactly what they are buying and what they can expect. High quality seed is determined by its parent’s genetic makeup, physical integrity and purity of the seed, seed health and physiological seed quality, explains Lahcen Grass, the global manager for seed biology testing and product marketing sup- port at the Syngenta Seedcare Institute. Alison Powell, a long-time member of the International Seed Testing Association (ISTA) and an honorary senior lecturer at the University of Aberdeen, says it’s important to define what we mean by “seed quality.” The term is wide ranging, she says, and encompasses purity, variety, problems of seed health, germination and vigor. She says it also includes whether or not the seed is genetically modified and factors such as moisture content and seed weight. “We hear a great deal about plant breeding, but the prod- uct of plant breeding is only as good as the quality of seed produced,” Powell says, noting much of that depends on seed production conditions. Grass agrees. “The quality of a given year’s seed is deter- mined by the prevailing weather and field conditions from the previous year, and subsequent processing and handling prac- tices,” he says, adding that you also have to consider if it was harvested at its highest point of physiological maturity. The latter property can be determined by two separate tests: a germination test and a vigor test. However, these tests are not created equal. For seed to be sold in the United States, the percent ger- mination must be printed on the each bag of seed. This value is derived from a standard germination test conducted under optimum temperature, moisture and light conditions. But, Grass says it’s important to recognize that some of these seed lots might not be capable of germinating or emerging under less than optimal field conditions. This places more importance on the vigor test. While each seed company has its own proprietary method for conduct- ing vigor tests, Powell points out that standardized vigor tests are published in the ISTA Rules for Seed Testing and are used worldwide. Vigor tests often impose stressful conditions on the seed during germination and emergence. The ISTA tests include several different tests but are all based on the main cause of dif- ferences in vigor, namely seed aging. “High germination seed lots from the same variety and year can yield good germination test results but score very different on vigor tests,” Grass says. “Generally, seed susceptibility to stresses that lead to poor and uneven field emergence are typical features of seed with lower vigor, not of lower germination capacity. “On the other hand, higher and uniform emergence and vigor- ous seedling growth are properties of seed with higher vigor and germination.” Seed vigor is unlike germination in that it’s not an absolute number. The expression of vigor depends on field conditions and is affected by oxygen uptake, water uptake and soil temperature. Thus all seeds will emerge well in favorable conditions and differ- ences in emergence due to vigor only arise in poor conditions. “Industry shouldn’t rely solely on germination tests, because it doesn’t give the complete story,” Grass says. “The good thing is all seed companies go the extra mile to conduct their own vigor tests. They invest their own resources because they don’t want to sell low vigor seed to customers.” Sarah Foster, president of 20/20 Seed Labs in Canada, agrees. “We have our sights set on seed quality and how the environ- ment could influence vigor,” she says. “With hybrid wheat on the horizon, quality, performance and vigor are key competing Seed quality is important not only to farmers, but a company’s reputation hangs on it. Seed World asks some of the industry’s foremost experts if testing methods are keeping up with technological advancements. Julie Deering Are Testing Methods Keeping Up with the Times?