Technology 22 www.seed.ab.ca | Advancing Seed in Alberta 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 support 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 vigour. 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 product 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 determined by the prevailing weather and field conditions from the previous year, and subsequent processing and handling practices,” 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 vigour test. However, these tests are not created equal. While each seed company has its own proprietary method for conducting vigour tests, Powell points out that standardized vigour tests are published in the ISTA Rules for Seed Testing and are used worldwide. Vigour 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 differences in vigour, namely seed aging. “High germination seed lots from the same variety and year can yield good germination test results but score very different on vigour tests,” Grass says. “Generally, seed susceptibility to stresses that lead to poor and uneven field emergence are typical features of seed with lower vigour, not of lower germination capacity. “On the other hand, higher and uniform emergence and vigorous seedling growth are properties of seed with higher vigour and germination.” Seed vigour is unlike germination in that it’s not an absolute number. The expression of vigour depends on field conditions and is affected by oxygen uptake, water uptake and soil temperature. Thus all seeds will emerge well in favourable conditions, and differences in emergence due to vigour 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 vigour tests. They invest their own resources because they don’t want to sell low vigour seed to customers.” Sarah Foster, president of 20/20 Seed Labs, agrees. “We have our sights set on seed quality and how the environment could influence vigour,” she says. “With hybrid wheat on the horizon, quality, performance and vigour are key competing factors. As scientists we have to work on new tests to determine what’s needed in the near future.” Grass says this information can then be used to rank seed lots based on germination. For example, if the germination rate is low, there’s no need to test it for vigour. With a focus on vigour, Powell and the ISTA Vigour Committee constantly think about the development of new tests and the potential for automation, which can dramatically speed the test results. For example, Powell says the radicle emergence test depends on the physical counting of emerged radicles, but the use of image analysis can drastically speed the process. Just as scientific advancements are made in plant breeding, so too are they in the seed testing sector. But are the rules and standards set forth keeping up with these new breakthroughs? Are Seed Testing Methods Keeping Up with the Times? Seed quality is important not only to farmers, but a company’s reputation hinges on it. We ask some of the industry’s foremost experts if testing methods are keeping up with technological advancements. Sarah Foster is president of 20/20 Seed Labs. Alison Powell is an international seed testing expert.