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05
May
2011
Understanding Soybean Seed Quality
Author: Jeremy Ross, Extension Agronomist - Soybeans

What is Seed Quality?

Seed quality is complex. Several factors influence seed quality including variety, purity, weather, insects, diseases, harvest moisture, handling, and storage.

Germination and vigor are quick and inexpensive lab tests that provide information about seed quality.

Germination stated on the seed tag is what you can expect under favorable moisture and temperature conditions. Seed vigor is more complex. It indicates the seed’s ability to germinate and establish “healthy” seedlings under stressful conditions.

Why is Seed Quality Important?

Seed is alive; and it can change over time under varying conditions. It can also vary from year to year as do planting conditions. When planting, seed vigor can be used to assist with management decisions, especially under adverse planting conditions.

Seed quality is critical in the establishment of a uniform plant stand, the first step in producing a successful crop, but good planting conditions are also critical since even high quality seed can fail under too much stress.

How is Seed Quality Measured?

Standard Germination Test
This test determines the percentage of seeds capable of producing normal seedlings under optimal conditions. Seed are placed in moistened germination towels, then held in a germination chamber for 6 to 8 days at either a constant 77°F or under alternating temperature conditions of 16 hours at 86°F followed by 8 hours at 68°F for 6 days. The percentage of normal seedlings are determined based on standardized seedling characteristics.

Results from a standard germination test are required by federal law to be provided for all seed sold. Variety, lot number and germ must be printed on bagged seed, bulk bag seed or on invoices for bulk seed. In Arkansas, germ results are considered good for 9 months, excluding the testing month.

Germination testing shows seed with poor germ, left, versus good germ, right.

Accelerated Aging(AA) Test
This is a more recent standardized test used to estimate the vigor of seed and help predict seed performance under varying conditions at planting. A precise amount of seed is measured and placed in a 100% humidity environment at 106°F for 72 hours, after which the seed are subjected to the standard germination test. The high humidity and temperature of the AA test stress the seed, and provides additional information about the overall quality of individual seed lots and where they could be used most reliably. Seed with germ above 80% and AA values above 65% indicates good seed quality, although no hard and fast AA thresholds have been established to date.

AA vigor testing shows seed with low AA results, left, and seed with high value, right.

Taking it to the Field

Arkansas varies in climate and geology making seed quality more important than in uniform production regions. Good quality seed, with high germination and vigor, is key to establishing a strong, uniform stand. Naturally, planting conditions are also important in stand establishment. Understanding and investing in high quality seed will help assure maximum yield and profit potential, while reducing risk of stand loss and management problems bassociated with weak and uneven stands.

Ask Questions about Seed Quality

For more information, contact your local county extension office.

Seed is a major investment. Keep good records. Save the tag or invoice stating the variety, lot number and germ – these are vital if something goes wrong.

Ask your seed dealer for all available information on the seed you purchase. And you can have your seed tested independently by private labs or by the Arkansas State Plant Board for a small fee.


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