Seed Quality
in 1999 Bin-Run Soybeans
Compliments
of Agronomy Services Department
Current Situation
Last fall, many soybean producers decided to save
some grain from their 1999 production for planting in 2000. This spring,
many producers are finding they do not have the level of seed quality
they expected to have in their bin-run beans.
Seed Quality vs. Grain Quality
Seed Quality and Grain Quality are often confused. A
seed is a reproductive unit with the primary purpose of reproducing. In
order for reproduction to occur, the seed must be living and capable of
germinating in a hostile field environment. Seed quality is the seed�s
potential to germinate. Grain quality is a measure of the seed�s
nutritional characteristics. High nutritional quality does not
necessarily equate to high seed quality or high germination rates.
Planting poor quality seed means fewer seeds
germinating, which means reduced stands. Poor quality seed often leads
to reduced seedling vigor. Less vigorous seedlings often do not survive
wet, cold, poorly drained soils, soil compaction, soil crusting, and
seedling blight (damping off).
Weakened seedlings are also more vulnerable to
diseases such as Fusarium root rot, Rhizoctonia root rot, and
Phytophthora root and stem rot. Plant shortened by these diseases,
contribute to harvest losses due to low pod height. Additionally, low
plant population results in reduced competition against weeds.
What Factors Affect Seed Quality?
Soybean seed quality can be negatively impacted by
problems during maturation, harvesting, conditioning, storage or
planting.
In terms of seed quality, the most critical period of
growth for soybean plants is the bean filling stage. During this stage,
which can be as long as 40 days in some varieties, environmental
conditions can greatly affect the growth and quality of the seed. Last
year, many soybean fields experienced hot, dry conditions during this
critical period, resulting in smaller, lower quality seeds.
Secondly, a timely harvest of soybeans is essential
to seed quality. High temperatures following physiological maturity can
reduce seed vigor. Soybeans with a moisture content between 10 and 14
percent are the most resistant to mechanical damage. Last fall many
producers experienced a rapid dry down of grain, and soybeans were often
below 10 percent moisture at harvest.
Mechanical damage to individual seeds may result in
reduced viability and serve as sites for disease and insect damage.
Optimizing harvest moisture and handling the seed carefully, such as
using belt conveyors rather than augers to move seed can reduce
mechanical damage. This is particularly important for soybeans because
soybeans have a very thin seed coat.
In addition to proper harvesting and handling, seed
quality can be improved in the conditioning process by removing split
beans and other foreign material (air-screen cleaner), irregularly
shaped seed (spiral separator), and lightweight, lower quality seed
(gravity separator).
Mycogen Soybeans � Quality from Planting to Bagging
Planting high quality Mycogen soybean seed has an
advantage over going to the grain bin for seed. Mycogen customers
purchase genetically pure seed with high viability, high germination
scores, and rapid and uniform germination (high vigor).
Every producer knows that seed appearance does not
determine the vigor or yield of soybeans. To ensure that Mycogen
customers receive the highest quality seed possible, the seed is tested
for genetic purity, germination, and seed vigor. The seed may also
undergo seed health tests for diseases such as soybean mosaic or bean
pod mottle virus to make certain the seed is free of seedborne
pathogens. Germination is measured by using the standard warm
germination test in which the seed is grown under optimum conditions (77
degrees F for 7 days). Vigor is measured by using the accelerated aging
test in which the seed is exposed to nearly 100% relative humidity and
106 degree F temperature for 72 hours and then planted in the
germination test.
Mycogen still has high yielding conventional and
Roundup Ready� soybeans available. Contact
your local sales representative for details.
