Seeds represent an important part of the total input costs in soybean production. Soybean seed cost is variable since it is associated with the crop expected yield and the requirements for other inputs. Whether your seed cost is 7% or 25% of the total operations costs, be sure to consider factors other than initial seed cost savings, for example, phytosanitary issues associated with the use of bin–run seed.
Grain or seed? Although the botanical definition of seed applies to the harvested grain, there are fundamental differences between seeds that will be used as planting material (seed), and seed that will be used for animal and human consumption (grain).
Seeds are living organisms, therefore, if their intended final use will be as propagating material, all management operations (in the field, during harvest, cleaning, storage and commercialization) should be focused on maintaining those seeds as viable, undamaged, pure, healthy, and vigorous for optimum germination. Certified seed has the highest quality available for crop production; therefore, seed certification requires quality controls in every step of the seed chain. Seeds purchased from reputable dealers come with a level of quality assurance that farm-saved seed may lack.
Soybeans can self-pollinate, and most of the progeny will have the same traits as the mother plant. Farmers know this very well, and with the next growing season approaching, the question that comes up is if farmed-saved seed or bin-run seed could be used as planting material.
The use of bin-run seed brings hidden costs and risks that have to be taken into account:
- When seeds are bought, there are license agreements that must be signed. Not complying with what is stated in the agreement can have legal consequences, like lawsuits.
- Appropriate tests should be conducted to know the seed germination percentage. This can be conducted in seed testing laboratories and is it required to calculate seeding rates and plant stand. The Pennsylvania Department of Agriculture offers germination testing for a small fee.
- Seed lots must be cleaned before storage. Appropriate seed cleaning equipment must be used to separate small/unhealthy seeds, rocks, plant debris, and weed seeds.
- Appropriate drying (i.e. drying temperature and drying rate) and storage are required to maintain a safe moisture content for storage, to ensure the embryo is alive and undamaged, and to suppress fungal and bacterial growth. It is important to also note that the seed lot may also contain “healthy looking” seed that is contaminated with pathogens.
- Planting seeds that carry diseases, or can serve as a source of more weed seeds, will have a direct negative impact on the input costs. A list of selected plant diseases commonly associated with seeds can be found in Table 1.
Table 1. Soybean diseases and their effects on soybean seed quality and yield.
|Causal Agent||Common Name||Impact|
|Phomopsis longicolla(syn. Diaporthe longicolla) –various fungi||Phomopsis seed decay||Affects yield, reduces seed viability and vigor. Seed is lightweight and shriveled.|
|Comovirus||Soybean bean pod mottle virus (BPMV)||Bean leaf beetle and aphids infect plants. Infected seeds are small and have brown or black seed coat mottling. Seed transmission occurs at low rates.|
|Potyvirus||Soybean mosaic virus (SMV)||Seed is primary source of inoculum. Affects amount and quality of seeds. Affects food grade soybean. Percentage of seed transmission is variable.|
|Sclerotinia sclerotiorum||Sclerotinia stem rot (White mold)||Affects yield and seed quality. Seed lots may contain sclerotia, the overwintering structures that serve as the pathogen source for the next growing season.|
|Cercospora kikuchii||Cercospora purple stain||Affects grain quality, may delay germination, and reduces seedling growth.|
|Peronospora manshurica||Downy mildew||Reduces seed quality. If infected seeds are planted, seedling growth may be reduced.|
|Colletotrichum truncatum||Anthracnose||Seeds look shriveled, with dark lesions. Infected seeds are prone to damping off, with a direct impact on germination.|
|Pseudomonas syringaepv. glycinea||Bacterial blight||Seeds may look healthy, discolored, or shriveled. The disease is seed transmitted. Reduces seedling growth.|
|Tospovirus||Soybean vein necrosis virus (SVNV)||Spread by thrips. Reduces seed quality. Seed transmitted, can be asymptomatic.|
Seed quality is set at harvest. Commercially available seed treatments will not improve seed quality; they will contribute to and maintain it by protecting the seed from certain pathogens and insects. Applying these products to the seed requires special equipment that will represent additional costs