April 5, 2001 | By: Laura Skillman
PRINCETON, Ky.

Weather conditions during last fall's harvest have resulted in considerably lower quality soybean seed than in past years.

With lower quality, farmers need to consider making changes in production practices, said James Herbek, University of Kentucky Extension agronomist.

Seed quality is probably the worst in recent memory, he said. Germination tests are commonly averaging 80 to 85 percent or 10 to 15 percent below normal, and some have tested as low as 60 to 70 percent.

The problem occurred because of rapid maturity last fall with hot, dry temperatures resulting in low seed moisture at harvest. Dry seeds are highly susceptible to mechanical damage at harvest and handling which can result in more split seeds, cracked seed coats and damaged embryos. That damage can result in low germination and vigor.

Other problems that also may have contributed to lower seed quality in some regions include an early frost that resulted in immature seed and diseases.

With the lower germination, growers need to be aware that seed vigor is also low. The germination test records the number of live, viable seeds, while the vigor test is an indicator of the seed's ability to establish seedling emergence under stressful planting conditions. Planting low quality seed under stressful conditions further reduces germination and emergence, Herbek said.

Lower quality is a fairly widespread problem even within the commercial seed industry, he said. Seed germination targets of 90 percent are proving difficult to meet and many companies have lowered their germination standards to 80 percent to meet the heavy demand for seed, Herbek said.

Some high demand, low supply varieties may be tagged at 75 percent germination, with appropriate price discounts, to meet seed demands, he said. It is important to check the seed tag this year to determine the quality of the seed purchased.

For farmers who save their own seed, it is particularly important to get a germination test and preferably a vigor test as well to determine if seed is suitable for planting. Even if a germination test was done in the fall, Herbek said, another is needed. Seed quality has deteriorated even further during storage.

Herbek said farmers may want to consider buying their seed now because good quality seed in certain varieties will be in low supply.

Also, increase seeding rates to compensate for lower quality seed. To determine your adjusted seeding rate, divide your seeding rate goal by the germination percentage.

Do not plant seed with germination below 70 percent. It would be better to find higher quality seed or you may end up with poor stands and incur additional costs for replanting, he said.

Do not plant lower quality seed in stressful planting conditions because of lower seed vigor. Plant only when soil temperatures are 65 degrees or above.

Handle seed carefully to avoid further damage to the low quality, fragile seed.

There are pros and cons to treating seeds this year, Herbek said. Seed treatments will help protect poor quality seed from soil-borne pathogens if planted under stressful conditions. They can also increase seed germination by 10 to 20 percent if infected with seed-borne diseases. But seed treatments do little to increase germination due to mechanical damage. Treatment cannot turn low quality seed into high quality seed, he said. It can only protect the quality that is already there.

Contact: 

James Herbek, (270) 365-7541