ALBANY, Mo. -- A small decrease in soybean germination rate listed on the seed tag can bring a big drop in actual germination in the field. That's what Steve Norberg discovered this year in a field test at the University of Missouri Hundley-Whaley Farm.
Norberg, regional extension agronomist at Bethany, Mo., compared seed with 90 percent germination to seed with 80 percent germination. When planted at 150,000 seeds per acre, the higher germination seed had a 93.5 percent emergence. The 80 percent germination seed dropped to 50.5 percent emergence in side-by-side comparisons.
"Germination listed on the seed tag doesn't tell the whole story," Norberg said. "It's [based on] a warm-germination test, which doesn't match actual field conditions. An accelerated aging or cold-germination test would tell a lot more about the vigor of the seed."
That difference was especially important this year when soybean seed was planted into cold, wet soil. "A good disease-resistant, vigorous seed is important when planting into an environmentally stressful situation," Norberg said.
In the test, Norberg also planted an extra 50,000 seed per acre in an attempt to offset the lower germination rate listed on the seed tag. "That helped increase the stand by about 31,000 plants per acre, but it would have been wiser to pay for 90-percent-germination seed than to use that money to buy an extra 50,000 seeds per acre," Norberg said.
The plots in the comparison will be on view at the Hundley-Whaley Field Day Sept. 6 at the farm located in southwest Albany. The field day opens at 8 a.m. and the last wagon tour leaves at 1 p.m. Plot yields will be available later.
Producers across northern Missouri noted reduced and erratic stands of soybeans this year because of poor planting conditions.
Adding to the problem was large quantities of poor quality seed produced last fall when soybean seed was harvested after a drought at abnormally low seed moisture. Dry soybeans are prone to have cracked seed hulls, which reduces germination.
Norberg noted that he was using commercially available seed. "Bin-run seed that had not been managed up to seed-industry standards may have had even bigger problems this year."
The field trial was started when seed industry representatives on the Hundley-Whaley planning committee pointed out that high quality seed was in short supply this year. Normally, seed is sold at 90 to 95 percent germination.
"Bottom line from this study is that excellent quality seed is needed," Norberg said. "If the warm-germination test is below 90 percent, than other tests will be more helpful for estimating field emergence."
The Hundley-Whaley Farm, part of the MU Agricultural Experiment Station, provides local test results for area farmers. Field day visitors will see hundreds of plots comparing corn, soybean and alternative crop varieties. The farm has one of the largest weed control tests in the Midwest.