The 2018 soybean seed production year presents some significant challenges for 2019 seed quality. Late fall rains throughout the Midwest coupled with warm fall temperatures setup conditions for the colonization of Diaporthe fungus. Some soybean seed quality data confirms the concerns of many seed producers about the lower quality seeds impact on emergence, particularly if growers plant into difficult soil conditions this spring.
There are various quality tests that can be performed on soybean seed lots to help producers determine the marketability of the lot. The warm germination test is required by seed laws for all seed sold. It measures the potential of the seed to germinate under ideal conditions. The warm germination percent is a vital measure of seed quality but it will not estimate how well seeds will emerge in cool or stressful soil conditions. Seed vigor tests place the seed in less than optimal (stressful) growing condition to determine if the seed will produce normal healthy development in a sub-optimal growth environment.
The two primary soybean vigor tests are the cold test and the accelerated aging (AA) test. The cold test stresses the seed with cool, wet conditions often incorporating soil to introduce pathogens. This simulates early spring planting conditions. The AA test first places seeds in a high temperature, high relative humidity environment to stress the seed before planting in a roll towel or on a tray. Both of these vigor tests correlate well with field emergence in less than ideal early spring planting conditions. Both seed vigor tests can be used to compare and rank seed lots. Growers can use this information along with seed maturity to determine planting order.
What can be done if the germination and vigor results indicate that seed quality is low and a grower will most likely have emergence issues? Using a fungicide seed treatment can protect the seed during the crucial moisture imbibition and seedling development stages when the crop is most vulnerable. Some treatment data show that germination scores can be improved by 10 to 15 percent when pathogens are present within the seed lot. Effective communication with growers is critical, recommending that vulnerable seed lots be planted later, under more favorable growing conditions. Companies can also recommend that growers increase the planting populations to compensate for potential emergence issues. Accurate seed quality data leads to good decisions. Be sure you have all the information that you need to protect your growers and your reputation as a quality soybean seed supplier.