Soybean Seed Quality
It's Not in the Bag!

Germination and vigour tests of soybean seed tested to date is very mixed. Seed quality from last year's crop is one of the poorest in history. Quality problems developed from last year's hot, dry conditions during flowering and seed development in late July and early August. Thrown into the mix was the soybean aphid explosion, followed by tarnished plant bugs that resulted in 'sting' marks on the seed. The end result is poor quality!

Seed companies are reporting high levels of cleanout on this seed. These conditions resulted in rapid seed maturation that was sometimes incomplete, and the seed went from green to brown without ripening properly. This results in fragile seed coats with higher levels of oval and misshapen seed that are much more susceptible to mechanical injury during handling. If seed became overdry (less than 13% moisture) during harvest, mechanical damage is increased. In a few cases, harvest was delayed last fall, due to wet October weather, resulting in further deterioration in seed quality.

Suggestions

• Select high-yielding varieties with good disease resistance/tolerance.

• Handle seed with care.. Minimize the drop distance when handling seed. Bulk transfer systems that use belts for moving seed are least damaging, followed by brush augers, plastic cup augers, steel auger and vacuum systems. Reduce seed damage by running systems full and slow.

• Vigour test ! In talking to several seed labs, most samples coming in are requesting only a germination test. UNBELIEVABLE ! The vigour (or stress or cold germ) test is a much better measure of "weak seed" that may fail to emerge under stress conditions. As seed deterioration increases, germination drops slowly, while vigour drops very rapidly. Diagram 1 shows the relationship between germination and vigour on two seedlots. With lot A, deterioration is minimal and germination and vigour are similar. Lot B has acceptable germination (near 85%) but extremely low vigour (only 40%)!

• Avoid planting soybeans at soil temperatures below 7 degrees C ( 45 F). There is a 2 hour delay between air temperature and tilled soil temperature at a depth of 2.5 cm( 1 inch). Imbibition of cold water can cause death or reduced vigour of soybeans. This is particularly important when seedlots have reduced vigour.

• Seed treatments help to protect germination and vigour of seed, and can improve emergence of seed with good germination but reduced vigour. Fungicide seed treatment helps to protect seedlings from early season diseases. (Vitaflo 280, Maxim/Apron, B-3 or DLC).