• Topics: Agronomy | Peanut Production | Peanuts | Whitty, Ben | Tillman, Barry L | Wright, David L

Producing Quality Peanut Seed¹

The cost of peanut seed for planting is a significant portion of production expenses. Compared to crops like soybean or rice, peanut seed are difficult to grow, store, and process. The seed are especially fragile after shelling because the thin seed coat offers limited protection from physical and other damage. Anyone planning to produce peanut seed should be prepared to provide the best care possible to the seed. Also, before producing peanut seed, the grower should be aware that the Peanut Variety Protection Act (PVP) and the awarding of utility patents to the high oleic characteristic may limit the production or sale of seed of certain varieties. See Agronomy Fact Sheet SS-AGR-186 : Farmer Saved Peanut Seed: Factors to Consider (http://edis.ifas.ufl.edu/AG189) for more information.

The three major components of peanut seed quality are purity, germination, and vigor. Seed certifying agencies provide information and inspection services that are intended to ensure that only high-quality seed are made available to growers. Producing peanut seed that meet these three quality components is a challenge from planting through harvest and processing. This document outlines and discusses factors that are important for producing high quality peanut seed.

Maintaining Seed Purity

Seed purity can be compromised by physical mixture with seed from other varieties, or genetically by outcrossing. To ensure purity, seed certifying agencies require growers to follow and document certain procedures when producing peanut for seed.

Certification Process

Practically all peanut seed are sold as a class of certified seed, and certification is usually required if plant variety protection is obtained. When a peanut variety is released, limited quantities of seed are available, so a systematic procedure begins that will increase the seed supply for commercial use while protecting the purity of the seed. This process begins with “breeder's seed”, the purest class of certified seed. Breeder's seed is planted to produce “foundation seed”. In Florida, the agency that produces foundation peanut seed is the Florida Foundation Seed Producers Inc. The next generation of seed is "registered seed," which is produced from foundation seed. Registered seed is then made available for sale to farmers or to seed producers who produce "certified seed," the next class in the certification program. The final step in seed certification is a class called "second-year certified seed". Naturally the supply of seed increases with each generation. In Florida and Alabama, the Southern Seed Certification Association certifies peanut seed (http://www.ag.auburn.edu/auxiliary/ssca/index.html), and in Georgia, the Georgia Crop Improvement Association certifies peanut seed (http://www.certifiedseed.org/).

During each step of seed increase, procedures to ensure purity must be followed if the seed is to receive the certification label. Documentation is required to show that the seed being planted were from an appropriate class of certification. During the growing season peanuts are inspected by the certifying agency to remove any plants that do not have the visual characteristics of the variety being grown. At harvest, the combine must be inspected to be sure that there are no peanuts left in the machine from previous harvests. Drying wagons and storage facilities must also be free of any other peanuts before the new crop can be put in them. These requirements and procedures help prevent contamination from volunteer or nearby peanuts, and also reduce the chance of cross-pollination by another variety.

Purity also means the absence of other seed and foreign matter. Unlike most other seed crops, peanut is not shelled as part the harvesting process. Due to the separate shelling process and the peanut seed being larger than most other weed seed, the presence of foreign matter and other weed seed rarely presents a problem in properly handled peanut seed.

Field Rotation and Isolation

Field selection is very important for producing peanut seed. In order to qualify for certification, peanut seed must be grown in a field that has not grown peanuts, or that has not grown the same variety of peanut from a lower classification of certification the previous two years. The two year restriction minimizes potential contamination from volunteer peanut plants that could sprout from previous peanut crops. In addition to a two year rotation, an isolation buffer must be placed between each different peanut variety that is planted in the same field. The minimum size of the buffer for peanut in Florida, Georgia and Alabama is ten feet.

Producing Seed with Good Germination and Vigor

State laws require that peanut seed meet germination standards before they can be sold as certified seed. While there are no standard vigor tests, it is important that peanut seed germinate uniformly and establish a healthy stand of plants very quickly. Quite often pre-harvest and post-harvest practices that contribute to good germination also promote good vigor.

Crop Management

Seed should be planted when soil and weather conditions favor rapid germination and emergence. Seed should be treated with an appropriate fungicide before planting to protect them from soil and seedling diseases. It is also important to calibrate the planter correctly and to make sure that the planter does not damage the seed during planting. Uniform stands and growth will contribute to uniform seed being produced over the entire field, which in turn should result in uniform germination and vigor. Preventing excessive pest problems also improves the probability that good germinating seed will be produced.

Calcium nutrition is very important in peanut seed production. A deficiency of calcium in the soil will result in seed with reduced germination, even when pod yield and grade are not affected. The calcium must be available in the pegging zone (top 3 inches of soil) of the peanut plant because the nutrient must be absorbed directly by the peg or pod. None of the calcium absorbed by the plant roots is translocated through the plant to the developing peg or pod. Often a calcium deficiency is visible as shown by "black heart," in which the embryo is black even though the cotyledons are healthy. Even if the calcium content of the seed is not low enough for black heart to be exhibited, germination may still be below standards if calcium levels are restricted. For this reason, gypsum is recommended for all peanuts being grown for seed without regard to the soil calcium level. Soil calcium levels may be adequate for seed production without the application of gypsum, but this level has not yet been determined. Gypsum may be banded over the potential pegging zone, or a width of about 18 inches over the row, at a rate of 400 pounds per acre of dry material. For a broadcast application of gypsum, use at least 800 pounds per acre. Increase the rate as needed if the gypsum contains moisture, which is usually the case with bulk loads. Apply the gypsum no later than the start of blooming because calcium uptake is most important as the peg enters the soil and the pod begins to enlarge. In the event of heavy rains soon after application, and before major pod development, a second gypsum application may be needed to compensate for possible leaching losses of calcium and thus ensure the quality of kernels that develop later. Calcium uptake is through the water absorbed by the pods, so irrigation is useful during dry periods to ensure consistent uptake through the season. Since uptake of calcium by the pods may be slowed by low soil moisture, so high soil calcium levels provide some protection during dry conditions. Some producers utilize calcitic limestone (Hi-Cal Lime) as a calcium source. Research has shown that lime, when applied to the soil surface in the late winter or spring can supply calcium sufficient for optimum pod yield and grade, however, calcium from lime is less available than from gypsum and may not supply the needs of a seed crop of peanuts. For this reason, gypsum is the preferred calcium fertilizer for peanuts grown for seed. Another factor to consider is the pod and seed size of the cultivar being grown. There are several large seeded runner type cultivars in the market today and their requirement for calcium appears to be greater than that of Georgia Green and Florunner, the historical runner-type cultivars.

To insure optimum germination, peanuts should be harvested when they are fully mature, as determined by the hull-scrape maturity test. Digging and harvesting equipment should be operated and adjusted to keep damage to the pods and seed to a minimum. Excessive levels of loose-shelled kernels indicate that adjustments should be made.

Post-Harvest Management

Do not dry peanut seed too rapidly or too dry, either in the field or on the wagons, because skin slippage and splitting of the kernels will be increased when they are shelled. Dryer temperatures should not exceed 100 degrees Fahrenheit and drying should cease when the moisture content reaches 9-10%. Use extra care in handling peanut seed to keep damage to a minimum. In addition to possible damage to the embryo, physical damage of the hull may promote insect infestations during storage and provide a means of disease entry after planting.

Normally the peanuts would be delivered to the contractor after they are dried, but if they are stored on the farm, keep the moisture content of the peanuts below 8 to 10 percent during storage. Under most conditions, the moisture content of peanut seeds will drop to about 6%. Running air through peanuts stored in wagons during times of low humidity such as in the afternoon on cool dry days or using fans blowing over the peanuts in bins should be adequate to keep moisture at a safe level. Check seed moisture levels periodically to be sure that they are at safe levels.

Since the seed quality is easier to maintain in unshelled peanuts, wait as late as practical to shell the peanuts. During shelling and all other subsequent handling be gentle with the peanut seed, because they are very fragile. Apply approved seed treatment fungicides before bagging. After bagging, do not allow the bags of seed peanuts to be thrown or dropped onto floors or truck beds, or to be exposed to excessive heat or high moisture. Generally, seed should be stored in a cool, dry location.

The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other extension publications, contact your county Cooperative Extension service.

U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A. & M. University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, Dean.

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