Information related to lower germination rates of soybean varieties has perked up the ears of many producers who will be dedicating ground to soybeans this year. Due to poor environmental conditions during last year’s harvest, many soybean seed lots targeted for use in the 2019 planting season have lower germination and accelerated aging (AA) scores than those lots sold and planted last year.
Germination tests are used to give a reasonable idea of potential field emergence under favorable growing conditions. The AA test is a vigor test that can be used to estimate field emergence under unfavorable conditions. “High quality seed will have germination numbers above 80 percent and AA numbers above 65 percent,” says Jeremy Ross, Extension agronomist, University of Arkansas.
Results of the 2018 non-certified soybean seed samples tested by the Arkansas State Plant Board (ASPB) through March 31, 2018, indicated average germination and AA scores of 86 percent and 77 percent, respectively. Forty-one percent of the samples tested this year scored below 80 percent on the germination test and 46 percent of them tested below 65 percent on the AA test.
“This decrease in germination and AA gives me cause for great concern for establishing adequate plant stands for this year’s soybean crop,” says Ross. “Every seed lot will not have low germination or AA scores, but many will have lower than ideal numbers.”
Ross understands most seed companies have already removed many of the seed lots from the market that scored low on this year’s germination tests. This has resulted in short supplies of the more popular varieties for this year.
Options?
All seed companies test for germination, but not all test for AA. Producers must do everything they can to succeed in getting adequate plant stands with their first planting. “The problem is, some of these testing results could be as much as two to three months old — depending on the storage and handling of the seed,” says Ross.
“To obtain the current quality of the seed they intend to plant, I encourage growers to send seed samples to the Arkansas State Plant Board’s (ASPB) Seed Division and pay the $12 for a current germination test and $8 for a current AA test.”
Test results can be used to better gauge a more optimum planting window, and seeding rates will need to be adjusted to compensate for the lower than ideal quality of seed. Testing and subsequent results from the Arkansas State Plant Board usually take 10 to 14 days. “I suspect many producers will have to adjust their planting schedules, but I firmly believe this will be time and money well spent,” says Ross.
Germination test results can be used to adjust seeding rates to compensate for the lower seed quality. Some of the seeding rate research Ross conducted the last couple of years shows a final plant stand between 80,000 and 100,000 plants per-acre will be needed to maximize potential yield.
“This may require seeding rate increases between 10 to 20 percent over regular seeding rates,” says Ross. “Because a variety’s accelerated aging score indicates how that seed will perform under unfavorable planting conditions like elevated soil temperatures and dry soil conditions — which typically occur during the latter part of the planting window, seed lots with higher AA scores should be planted during this timeframe.”
Ross has heard a lot of discussions lately about whether or not to use insecticide/fungicide seed treatments on poor quality seed. Because of the prolonged wet weather during last year’s harvest season, higher than normal seed-borne pathogens have been observed.
“Fungicide seed treatments may help control these pests, but if seed-borne pathogens are not prevalent, seed treatments will not dramatically increase seed quality or emergence,” says Ross.
A good insecticide/fungicide seed treatment is recommended on each seed lot to preserve existing seed quality. Combining results from a current germination test, seed treatments, adequate soil moisture and proper planting depth will help toward getting a good stand of soybeans from that first planting.
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