How to condition grain for seed
If you would like to save part of this year’s wheat crop back to use as seed on your own acreage first make sure it is allowable, as mentioned in an article in the June 9, 2022 issue of the Agronomy eUpdate. While most wheat varieties are protected by Plant Variety Protection which allows for keeping seed to plant on your own acreage, additional licensing and/or marketing restrictions may apply to some varieties referred to as Certified Seed Only (CSO), which removes this allowance. This includes all varieties carrying the Clearfield and/or the CoAxium technology for herbicide resistance, as well as many conventional wheat varieties. Consult your seed dealer for varieties that are not allowed to be planted back.
If saving the seed for your own use is allowable, you then have to decide whether to just use the wheat as bin-run seed or have it cleaned and conditioned.
Using bin-run grain as seed
With the drought-stress and heat-stress that the wheat suffered during much of the critical spring growing period in Kansas, the kernels of this year’s crop may well be small and shriveled, with light test weights – although some of the cooler and moister conditions experienced late May could have alleviated some of this issue. This was discussed in the June 9 article mentioned above.
Likewise, in-season crop management decisions can impact the next crop’s seed quality and viability. For example, spraying in-season foliar fungicide after the flag leaf is fully emerged can improve the harvested seed test weight, even in conditions of low disease pressure. Likewise, if weeds such as feral rye or jointed goatgrass were visible at harvest, these could be harvested together with the wheat seed and become a much greater issue next season. Thus, when selecting a field from which grain will be kept as seed, it is important to consider how the field was managed. Preference should be given to fields with appropriate agronomic management where foliar fungicides were sprayed, weeds were properly controlled, and there were no obvious signs of nutrient deficiencies.
Using this wheat as bin-run seed without cleaning or conditioning would be the least expensive approach in terms of up-front costs, of course. Bin-run seed always has the potential to be contaminated with weed seed, and to have higher amounts of small and light-test-weight seed than conditioned seed. This year, those disadvantages may be even more of a problem than usual, resulting in a crop with below-average vigor and yield potential.
Cleaning and conditioning the grain for seed
There are several steps you can take to condition the wheat from this year’s crop for use as seed. One of the first things to do is make sure the grain is aerated in the bin. High-moisture weed seeds and foreign material can quickly heat up wheat in the bin, and reduce the potential seed quality of the grain. Wet grain can also harbor insects.
Cleaning the grain is important if it will be used for seed, and should be done as soon as possible after harvest. That way, you can determine if you have enough seed to meet your needs. Cleanout may be especially high this year to get acceptable seed quality.
At a minimum, wheat should be cleaned with a 5/64 screen. It would be best to use a 5.5/64 or 6/64 screen. This may clean out more wheat than you’d like if the kernels are small and shriveled, but using small kernels as seed can cause vigor problems and reduce yield potential of the subsequent crop.
An air/screen cleaner is the most common piece of seed cleaning equipment. If operated properly, an air/screen cleaner will remove all the weedy annual brome species, such as cheat and downy brome, from wheat. Recent K-State research conducted for 3 years in 27 locations demonstrated an average yield gain of about 2 bushels per acre resulting from air screening the seed as compared to using bin-run seed straight. Gravity tables are excellent at sorting out the test weight difference in a lot of seed, but really depend on the air/screen cleaner to do the bulk of the cleaning job by first removing the trash, small seed, and weed seed. The gravity then separates seeds that have similar width, but slightly different densities. The same multi-year and multi-location research mentioned above demonstrated an additional yield gain of 2 bushels per acre when seed was cleaned in a gravity table as compared to air-screen only. In between the air/screen and gravity table, some facilities will use a length grader to separate jointgrass and or buckwheat, because they are similar in width to wheat.
Having the wheat cleaned with an air/screen cleaner (and possibly a length grader if there is jointgrass or buckwheat contamination) is the most important step to take. A gravity table is a good piece of secondary equipment to help raise the test weight, if that is a concern.
If there was rye or Italian ryegrass in the field, the wheat should not be planted back. In that case, it’s best to sell the wheat and take advantage of the current cash market for grain, then buy new seed.
Germination tests and seed treatments
Producers should have the seed tested for germination by a reputable laboratory. Home germination tests are not as accurate and reliable. The standard germination test will test for maximum seed germination potential under normal conditions. An Accelerated Aging germination test will test for seed vigor under stressful conditions and will reveal weaker seeds. More information on germination testing is available in a companion article in this eUpdate issue.
If there was loose smut present in the field, producers should have the seed treated with a fungicide seed treatment if they choose to keep that wheat for seed. This should either be applied by a professional seedsman or with an auger-based system on-farm. Drill box treatments do not do an adequate job of coverage.
Producers should plant the best quality seed possible this fall to get good emergence, early season vigor, and yield potential. It makes no sense to plant poor quality seed that will just create more problems next season. Certified seed is the best option, but keeping their own seeds can also result in good performance next season provided that the seed is coming from a well-managed field and is well cleaned and conditioned. If purchasing certified seed, producers should order their seed as soon as possible.
Romulo Lollato. Extension Wheat and Forages Specialist
Eric Fabrizius, Associate Director, Kansas Crop Improvement Association