Small Grains Focus

Steps to Improve Saved Seed Quality

By Jochum Wiersma
U of M Small Grains Specialist
wiers002@umn.edu

Good quality seed is a prerequisite to start the growing season. Buying certified seed is the best way to guarantee seed quality, and research has shown that certified seed has a yield advantage over equivalent saved or bin-run seed. However, when using bin-run wheat seed you can also take steps to improve and help ensure seed quality by considering the following steps.

Follow the Law -– The Plant Variety Protection Act allows farmers to save seed of protected wheat varieties for planting on their own land, but no protected seed may be sold, conditioned, or purchased without permission of the seed developer.

Plan Ahead -– The decision to use bin-run seed should have been made last year. Exercising good weed and disease control are two important first steps to ensure quality seed.  Evaluate the field for loose smut infections. If infections exceed 1%, automatically consider a seed treatment when using the lot for seed as loose smut is a seed-borne disease. Do not use seed from fields that were treated with a pre-harvest application of glyphosate.

Keep it Clean -– Take care to avoid co-mingling of healthy wheat seed with other varieties and other crops, weed seed, trash and debris and mechanically damaged wheat seed. Clean combines, trucks, augers, and storage bins.

Use Proper Handling and Storage -– to avoid damage to the seed and germ, harvest the seed close to 14% grain moisture.  Try to avoid cracked and damaged kernels by fine-tuning your combine’s settings.  When using aeration to dry the grain, avoid using high temperatures (> 110°F) when using forced air.

Guidelines for minimum seed quality parameters

Crop	Test Weight -lbs/bu-	Germination - % -	Cold Stress - % -
Spring Wheat	56	85	80
Winter Wheat	56	85	80
Durum Wheat	56	85	80
Barley	44	85	80
Oats	26	85	80

Do a Quality Check on the Seed Lot -– before deciding to clean and condition a bin of grain to be used as seed, do an initial quality check.  This check should consist of a visual inspection of the seed lot and a germination test of a small sample of whole, healthy-looking kernels.  Visually inspect what percentage of the kernels is broken, shrunken, shriveled and discolored. Use seed that is free of scab and black point, both of which can cause seed-borne root rot. If a large percentage of the seed lot is poor quality seed, do not use it, since the cost of cleaning and conditioning the seed may outweigh the savings of using bin-run seed, and cost you in poor yields. Do a germination test on a single sample of 50 seeds using the protocol for the germination test, described later in this article.

Clean and Condition the Seed Lot -- cleaning and conditioning the seed will allow you to remove the physical impurities (broken kernels, weed seeds, debris, etc.) and, up to a certain point, improve vigor.  Although high test weight in itself does not improve seed vigor, removing shrunken and shriveled kernels and consequently improving test weight will generally improve the seed lot’s viability and vigor.

Determine the Seed Count -– Why? Because kernels per pound can differ by variety, affecting seeding rate and plant population.  The simplest method to determine the number of kernels per pound of seed is to count and weigh one hundred kernels and calculate the weight in grams per 1,000 kernels. Divide 454 by the average weight.  Multiply this answer times 1,000 and this gives you the number of kernels per pound of clean seed.

Example: 100 seeds weigh 2.89 grams

(453.6 gm per lb) ÷ (2.89) x 1,000 seeds = seeds/lb
(156.95) x (1,000) = 156,950 seeds/lb

How to Conduct a Germination Test

A germination test is designed to determine seed viability under ideal conditions.  The test is conducted on a representative sample of pure seed.  Pure seed is defined as seed that is free of debris, inert matter or seed of other crops and weeds. When purchasing certified seed, an official germination test is conducted using a standard protocol. The following is an adaptation of this protocol that can be used at home.

1) Purchase thick paper towels that are highly absorbent and stand up well to wetting. Not necessarily use those that absorb the most water. Wheat needs oxygen to germinate.

2) Count 2 times 100 seeds from the seed lot that you want to test. These will be your 2 replications.

3) Fold the paper towel double along the width of the towel and wet it to the point of saturation.

4) Open the paper towel and lay the seed approximately 1 inch above the crease of the fold, making sure that seeds do not touch one another. A ¼” spacing is generally adequate. Depending on the size of the paper towel, you can probably place 20 to 25 seeds per towel. Thus you will have 4 or 5 sub-replicates per 100-seed sample.

5) After you have placed the seed along the crease, fold the towel and very carefully roll up the towel. Try to make sure the seeds do not move up or down.

6) Place the rolled up paper towel upright in a container.  Because you placed the seed 1-inch above the fold, you now have the opportunity to add water and ensure that the towels do not dry out.

7) Place the container in a location in which the ambient temperature is approximately 70°F.  If the seed is tested in the late summer or early fall when it was harvested, the seed will likely still have a high degree of post-harvest dormancy. To break this dormancy, pre-chill the seed by placing the containers with the wet paper towels at 50°F for 5 days before transferring it to an ambient temperature of 70°F (Pre-chill all durum wheat).

8) Count the number of normal seedlings after 4 days and make a final count at 7 days. A normal seedling is defined as a seedling that shows both healthy roots as well as a healthy shoot.  If the seedling is infected with fungi and shows mold growth, it can still be counted as a healthy normal seedling if all essential features are developing normally. To prevent contamination of other seedlings, you may opt to remove seedlings that are badly damaged by fungi or bacteria on the first count. If after 7 days some of the seeds swell with water, are firm, and show no evidence of disease but don’t germinate, they may have a membrane that is impermeable to oxygen. Poke these seeds with a needle and wait a couple of day to see if they will germinate. If they sprout you can add them to your normal seedling count. This new seed dormancy is found in new seed tested in the fall or seed lots that have been stored under high moisture conditions.

9) After the final count on day 7, you can calculate the percent germination by dividing the total number of normal healthy seedlings in each replicate by 100. The two numbers that you have will likely not be the same. The cause of this difference is random sampling error. A difference of up to 10% between the two replicates is no cause for alarm.  Calculate the average of the two replicates and use this number to calculate your seeding rate. Retest if the difference between the two replicates exceeds 10%.

The cold stress test is routinely done in both corn and soybeans to determine the vigor of a seed lot. Seed companies base their decision to sell a particular lot not only on the germination test but on the results of the cold stress test. The test can readily be adopted for use in wheat and other small grains.  The objective of the cold stress test is to evaluate the potential field emergence of wheat seed under unfavorable field conditions.  It is a measure of seed vigor and is especially important for seed lots that were held over for one or more years. The cold stress test is conducted as follows:

1) Purchase two plastic storage containers with snap-on lids that are approximately 7½” x 10” x 4” in size.  Plastic shoe box sized storage containers are an excellent choice.

2) Make a mixture of 2 parts of sand and 1 part soil. You can use dry sand and soil from your farm.  Remove large debris from the soil and screen it through ¼ inch mesh screen. Let the soil stabilize for a couple weeks before blending and using it. 

3) Put a pint of the sand/soil mixture in the bottom of the plastic container and place the 100 seeds on the surface of the soil.  Cover the seed with about 3/8” of the sand/soil mixture. Repeat this for the second container.

4) Add enough water to the containers so that you reach about 70% saturation.  This is a bit tricky, but as a rule of thumb, carefully add the water to the sand/soil mixture until it readily absorbs the water and no free water is visible at the bottom of the container.

5) Close the lids and put both containers at 50°F for seven days. After seven days, move containers to room temperature (70-72°F) and continuous light and count the number of healthy seedlings after 5 days.