Germination testing validates quality and vigor
Some seed corn can germinate and thrive in cold, wet spring soils. Some can’t. The challenge is to know, before you plant, which seed has a high enough germination rate to handle harsh weather conditions. That can help you determine when to plant or, in extreme cases, whether you need to return the seed to your supplier.
Doug Rupp learned these lessons this past spring as a result of investing in saturated cold germination tests. One seed lot he tested indicated that only 20% of the seed would likely germinate if planted in cold, wet soils.
"I sent 70 bags of seed back that had a problem I wasn’t aware of until the tests were done," says Rupp, who farms 2,000 acres of corn and soybeans near Stryker, Ohio
The experience has given Rupp a new perspective on the value of germination tests. "I used to be reluctant about sending seed off to be tested, but not anymore," he says.
A choice of tests. Hundreds of farmers who practice precision farming are investing in annual seed testing, says Tim Gutormson, seed services director for SGS North America in Brookings, S.D. "Vigor tests provide another piece of information that can help rank the planting order of seed lots to achieve a targeted plant population," he adds.
SGS receives requests from corn growers for four types of seed tests: standard germination, cold germination, saturated cold germination and the pericarp damage test. The tests range between $16 and $35, and farmers typically invest $75 to $100 per lot in testing, Gutormson says.
The standard germination test, or warm test, is conducted under optimum conditions to see what the maximum germination level is for seed. This seed germ percentage is what usually is represented on the bags or containers of seed you purchase.
The cold test involves planting the seed under 1" of sand that has a 70% water-holding capacity. The idea is to simulate being planted in wet, 50°F soils. The seed is stressed in this manner for seven days and then moved into a chamber with a temperature of 75°F to determine its germination rate.
The saturated cold test is the most stressful cold vigor test SGS conducts, Gutormson says. The seed is placed in 1⁄8" of soil at 50°F and is then saturated with water to represent 100% of a field’s water-holding capacity. This restricts the seed’s ability to take up oxygen/exchange gases and creates respiratory stress in addition to stress from the cold water uptake.
"The saturated cold test simulates severe conditions that farmers may face only one out of every 10 years," Gutormson says.
The pericarp damage test involves the seed being soaked in a solution of water and a dye. The dye colors the places where there are breaks and damage to the seed coat.
This test is particularly useful to farmers who want to use starter fertilizer in the seed furrow, says Missy Bauer, Farm Journal Associate Field Agronomist.
Bauer adds that farmers will sometimes need to accept a corn hybrid with lower saturated cold and cold germination scores if the hybrid offers high yield potential for their area. "You may just need to plant those hybrids when the weather is more favorable, so they go into warmer soils and have the opportunity to perform up to their potential."
Farm Journal Field Agronomist Ken Ferrie says that overall, the seed industry does a good job of quality control with its products and that it’s ultimately a farmer’s responsibility to understand seed quality and manage seed effectively for optimum results in the field.
For testing purposes, Ferrie recommends that farmers prioritize the seed they want to evaluate for germination quality. Potential candidates you may want to consider:
- discounted seed;
- seed from suppliers you question;
- seed you plan to plant first, probably in your coldest soils; and
- seed that will be planted in tough soils where the fields have a history of emergence and disease issues.