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National Seed Laboratory
5675 Riggins Mill Rd
Dry Branch, GA 31020

(478) 751-3551

 United States Department of Agriculture Forest Service. USDA logo which links to the department's national site. Forest Service logo which links to the agency's national site.

The National Seed Laboratory

The Mission
Worldwide and national interest in planting trees is at an all-time high. Campaigns carried out by such groups as American Forests (Global ReLeaf) and the National Arbor Day Foundation are signs of this high interest. The success of these and other planting programs depends on high-quality seedlings - and good seedlings start with high quality seed. The mission of the National Seed Laboratory is to assist in providing a quality start for global reforestation.

Photo of nursery         Photo of reforestation

Seed Certification
Planting seeds or seedlings that are not adapted to the planting site or suited to the landowners management objectives can lead to planting failure, financial loss because of poor growth or disease, or damage to the environment by disrupting naturally occurring plant populations. Seed certification is the process of certifying the genetic identity of seeds for agricultural, horticultural, or forest and conservation plantings. It can be extended to include the seedlings produced from certified seed when seedlings and not seeds are planted by the end user. This process either certifies that the variety or source of plant material (seed, seedling, or cutting) is adapted for the planting area or that the genetic identity is completely and unambiguously stated so that the landowner can make an informed and responsible decision about the materials planted. Seed certification is done by the individual states. Some states have active certification programs in trees and native plants while others have yet to develop their program. For information on the certification agency in your state, contact the Association of Official Seed Certifying Agencies at

photo of colored tags

Certification is generally offered at four levels. The first is simply to identify the source of seed, where are the parent plants growing and what is known about their origin. This category is referred to as source identified and is marked with yellow tags. The next category is stands of plants that are above average in some particular trait. This is the selected category and is marked with green tags. When plants are assembled in one planting site from various locations because of their above average appearance (superior phenotypes), it is called a seed orchard. Initially this seed orchard is called phenotypically superior and marked with pink tags. When progeny, seedlings or seeds, from a seed orchard are proven to be genetically superior in a test, they are classified as tested and marked with a blue tag.

The National Seed Laboratory assists with certification programs by participating in the Northwest Forest Tree Seed Certifiers Association, the Tree, Shrub, and Native Plants Committee of the Association of Official Seed Certifying Agencies, and by serving as the designated authority from the United States to the Scheme for the Certification of Forest Reproductive Materials Moving in International Trade operated by the Organization for Economic Cooperation and Development. Assistance has also been provided to individual states as they develop or administer their tree and native plant seed certification programs.

International Seed Bank

In 1972, the U.S. Department of Agriculture appointed the National Seed Laboratory to serve as the National Seed Coordinating Center for the Exchange of Forest Tree Germplasm among countries participating in the Food and Agricultural Organization (FAO) of the United Nations. Laboratory personnel assist embassies and other agencies in locating tree seed and in avoiding duplication of effort in filling international requests.
The seed bank provides small lots of native tree and shrub seeds to forest researchers outside the United States. The seed is available in quantities of either 200 or 2,500 seeds, according to customer preference. More than 150 species have been shipped to 95 countries since 1972.

Photo of packaged seed Seeds are packaged and shipped to forestry researchers and other clients around the world.


Technical Assistance

Technology Adaptation
The National Seed Laboratory is at the forefront in developing new forest seed technology. The latest equipment for seed conditioning and seed testing is evaluated and adapted for use with tree seed. New ideas to improve the seed-to-seedling ratio in forest nurseries are evaluated cooperatively with nursery and reforestation personnel.
Photo - Technology Adaptation Laboratory personnel discuss the latest technologies relating to hardwood seed.
Tree seed users are assisted in solving their collection, conditioning, handling, testing, and other seed related reforestation problems. Short-term studies are conducted to determine what corrective action is needed. Seeds of any forest plant can be submitted. Contact the laboratory (Contact Us page)for arrangements to submit a seed lot for examination or conditioning.
The National Seed Laboratory is a model for other organizations testing tree seed. Individual and group training is provided on testing procedures and the interpretation of the seed test results. Such training also extends to agencies in other countries. Foreign scientists and practitioners frequently spend short training periods at the lab to study the latest techniques in analyzing tree seed.

Workshops are also presented on conditioning seeds. These are done both at the laboratory and at cooperators' locations. Workshops are organized to meet the clients particular needs. Past workshops have emphasized hardwoods, conifers, prairie plants and combinations of them. Contact the laboratory (Contact Us page) for workshop dates or to arrange for a workshop in your area.
Photo - Training Outside groups visit the lab for training in proper seed sampling techniques.


Testing for Seed Quality

The National Seed Laboratory provides seed testing services to both small and large private firms, state governments, national forests and other federal agencies. The results of these test are used in forest nurseries to determine sowing rates, in seed conditioning plants to evaluate product quality, and by seed dealers to determine price.

The National Seed Laboratory measures seed quality with the following tests: germination, purity, moisture content, and seed per pound. Rapid estimates of viability are made by using chemical stains, embryo excision and x-rays. All tests for domestic use are performed according to the rules of the Association of Official Seed Analysts (AOSA).

Photo of seeds being examined.
Seeds are examined carefully to avoid mixing species and to detect contaminants.
Photo of germinated seeds
Pure seeds are germinated under ideal conditions in a controlled environment.
The National Seed Laboratory is accredited by the International Seed Testing Association (ISTA) and can issue ISTA seed analysis certificates. These certificates report seed test results required for international sales.
As members of AOSA and ISTA, the laboratory's specialists develop the official seed testing criteria and procedures for U.S. native tree and shrub species.

Seed Test Definitions

Germination of seed in a laboratory test is used to predict the probability that the seed will produce a normal plant under favorable conditions. The test measures the percentage of seeds that germinate and the speed of germination.

Moisture content is the percentage of water held by the seed. It is calculated by measuring the loss of weight by the seed when it is dried at a constant temperature for a specific period of time. Moisture content is a critical factor in storing seed because seed that is too moist cannot be stored and will deteriorate rapidly.

Purity distinguishes the amount and type of impurities in a seed sample. The impurities are physically removed from the seed sample in the laboratory leaving only the pure seed. A minimum weight that contains 2500 seeds is needed to conduct the test.

Seeds per pound determines the number of individual seeds in a pound. This value is used with the germination percentage and purity percentage to predict the number of seedlings expected to be produced by a given weight of seeds.

Estimated viability tests are for quickly determining the number of live seeds in a sample. The tetrazolium, excised embryo, and x-ray tests are the viability tests used most frequently at the laboratory. They are the preferred tests for very dormant seeds (seeds that are difficult to germinate).

In the tetrazolium test, a colorless solution of tetrazolium chloride is imbibed by the seed. Living tissues then stain red while dead tissues retain their natural color. Properly stained seeds are considered viable while improperly stained or unstained are generally considered non-viable seeds.

In the excised embryo test, the embryos are excised and incubated under prescribed conditions for 5 to 14 days. Viable embryos remain firm or exhibit evidence of growth while non-viable embryos show signs of decay.

X-radiography is used to examine the internal structures of the seed. It provides a quick, nondestructive method of differentiating between filled, empty, insect damaged, and physically damaged seed.



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