By: Ernie Flint, Ph.D., CCA, Area Agronomist, Central
Mississippi
Mississippi State University Extension Service
(February 8, 2010) -
Archaeologists tell us that the earliest humans did not plant seed and
harvest crops. Instead, they gathered the increase from native plants.
Agriculture started when they discovered that seed emerged to produce new
plants. They began planting “crops” instead of wandering about. Some
plants were found to be more productive than others, and some were preferred
as food crops. Over time, these were domesticated and selected for yield,
adaptability, quality, and other characteristics. If we could travel back a
few centuries in H.G. Wells’ Time Machine, we would scarcely recognize
earlier forms of crops like soybeans, cotton, corn, rice, and others.
Selection and hybridization have produced the important food crop plants
that sustain our modern world. This entire system is dependent upon the
production, care, and distribution of seed that is planted by farmers every
year.
Many things have changed through the centuries; but man
has not been successful in avoiding the effects of weather on the production
of crops, and consequently the quality of seeds varies greatly with
weather. Some years favor the development and maturation of excellent
quality seed that are capable of producing uniform stands of healthy plant.
In other years, weather conditions may lead to the production of poor
quality seed. We have developed methods for avoiding some environmental
effects; but in general seed quality varies almost directly with conditions
during the period of seed maturation.
Plants vary in their ability to produce good seed under
poor weather conditions. Monocots (plants that have only one leaf
compressed within the seed) like corn, sorghum, wheat, and other grass crops
usually produce good seed since their seeds contain very small amounts of
oil. Many dicots (plants with two leaves compressed within the seed) store
large amounts of oil in their seed. This oil is subject to deterioration
into organic acids as the result of unfavorable conditions. These acids
then produce rapid seed deterioration. Consequently, seed with high oil
content (like soybeans, cotton, peanuts) are generally most susceptible to
the production of poor quality seed during unfavorable weather.
Finally, we arrive at the point, which is that crops
like soybean and peanut are the most difficult when it comes to producing
good seed. Quality must be good at maturity; and great care must be
exercised during harvest, handling, processing, and storage of these seeds.
Both germination and vigor tests should be considered before planting; and
only those with good vigor should be planted when field conditions are less
than ideal. Last years’ field conditions were difficult in many seed
production areas; so growers should take special precautions to ensure that
planting seed are good before planting.
Common
sense things like physical appearance of the seed, including variable color,
split seedcoats, and other abnormal characteristics can suggest problems.
Laboratory tests for germination and vigor on samples taken after arrival at
the dealer or the farm can help avoid problems. When time is limited, the
tetrazoleum or “TZ” test can be done in less than two days. This test,
which was thoroughly studied at Mississippi State for many years, is very
good when done by a trained analyst. Most laboratories can perform the TZ
test. Call us if you need this or other tests done on your samples.
The first thing seed lose is their vigor. Seed can have
90 percent germination and 40 percent or less on a vigor test like TZ. They
can also have 90 percent germination and 70 percent TZ. When you plant them
there will be no doubt which is the best because you may have to replant
fields where you used the low vigor seed. I am well aware that this is not
a perfect world; and that many things happen that are beyond our control.
Ensuring that the seed we plant are good is one of the variables we can do
something about. Maybe the Lord will help us with some of the others; but
let’s take care of this one ourselves. Thanks for your time.
