Indelicate handling systems can damage germination rates in soybeans
Modern seed handling systems can damage seed and reduce germination, especially in sensitive soybeans.
“Soybeans are the poster child for mechanical seed damage and its effects on germination and seedling vigor,” says Alan Gaul, seed conditioning specialist at Iowa State University. “They’re sensitive not only to splitting, but damage to the seed embryo that can influence early seedling growth.”
YIELD-LIMITING ISSUES
An Ohio State University (OSU) study compared germination after soybeans were transferred with various systems. Germination decreased in the following ways:
- Plastic cupped auger: 1.5%
- Belt conveyor: 6%
- Steel auger: 7%
- Brush auger: 7%
“That study showed the importance of the design and operation of an entire transfer system,” Gaul says. “Belt conveyors are relatively gentle on beans, but the inlet and discharge conditions can substantially affect mechanical seed damage.”
Other studies indicate:
- Steel augers traditionally create the most seed damage, but that damage varies with design. “Auger designs with the screw flighting fully supported by hanger bearings at both ends of the auger cause less damage than augers with one end ‘floating’ in the tube,” Gaul says.
- Damage levels for nylon bristle augers were similar to conventional steel augers, per the OSU study. But nylon bristle augers tend to capture soybeans in the bristles, creating the potential for cross-contamination when working with GMO and non-GMO products.
- Cupped plastic augers produced only 1.5% damage in the OSU study, better than the belt conveyor’s 5.1% damage, but, “I would expect that a well-designed belt conveyor would have less seed damage compared to a cupped plastic auger,” Gaul says.
“There are many factors that contribute to mechanical seed damage,” Gaul says, “but most involve a combination of seed impact velocity, shear points, contact with sharp edges, or seed coat abrasion. Proper selection, maintenance and operating procedures can help maintain seed quality during bulk handling.”
