Amarillo, Texas
February 18, 2005
Cotton producers who catch their
own seed for planting should pay particular attention to seed
quality this year, said a
Texas Cooperative
Extension cotton agronomist.
"High quality seed is crucial for establishing a good stand.
Some producers are reducing seeding rates due to seed costs and
new precision planters. This makes seed quality even more
important," said Randy Boman, Extension cotton agronomist based
at Lubbock. "Many growers still opt to plant conventional
varieties using delinted, treated and bagged seed from the
previous crop.
"We experienced cool, wet fall conditions on the South Plains in
2004, and we harvested some immature cotton. Both can reduce
seed quality. If you plan on reducing seeding rates in 2005 or
planting saved seed from conventional varieties, you should take
extra steps to ensure seed quality."
Information from Norman Hopper, Texas Agricultural Experiment
Station and Texas Tech seed physiologist, provides some
guidelines for checking seed quality, Boman said. Hopper
conducts research on seed quality and seedling vigor.
"One way to gauge the quality of fuzzy seed is to test its
free-fatty acid content," Boman said. "One lab here in Lubbock
offers this test for $15 per sample, with a one- to two-day
turn-around."
"Fuzzy" seed is separated from cotton lint during ginning, and
has short cotton fibers on its kernel.
To obtain a good random seed sample, producers should take a
quart of seed from eight to 10 locations in a seed lot. Mix
thoroughly in a large tub or container and pull a 2-pound,
half-gallon sample from the mixed seed.
"If the lab results indicate a free-fatty acid content of 1
percent to 1.5 percent, the quality of that seed is suspect. It
may already be deteriorating, and it isn't suitable for
planting," Boman said. "Even if the free-fatty acid content is
less than 1 percent, it's a good idea to run two germination
tests on fuzzy seed."
A warm germination test costs about $9 per sample, and a cool
germination test costs about $12 per sample. The Texas
Department of Agriculture's Seed Testing Lab in Lubbock offers
both tests, with a two-week turn-around time for each test,
Boman said.
"You can submit fuzzy seed or delinted, gravity-sorted seed for
either test, but remember that germination percentages will be
higher for delinted, gravity sorted seed," he added.
A second gauge of seed quality is the cool-warm vigor index,
which combines the results of a seven-day cool germination test
and a four-day warm germination tests. It costs about $21 to run
a cool-warm vigor index test on a one-pound acid delinted seed
sample, and the turn-around time is about two weeks, Boman said.
"Pull a representative sample from several bags in the same seed
lot, but do not combine lots or varieties," Boman said. "It's
best to submit a separate sample for each variety or each seed
lot."
The cool-warm vigor index rates seed quality by number, in four
categories. Excellent seed has an index of 160 or greater. Good
seed has an index between 140 and 159. Fair seed has an index
between 120 to 139, and Poor seed has an index below 120.
"Producers should use their highest vigor seed for early
planting, or when field conditions are less than optimum. They
should use lower vigor seed for later planting, when soil
temperatures and other field conditions are optimum," Boman
said.
"There is nothing wrong with seed in the Good vigor category,
but seed that rates as Fair should be earmarked for late
planting or replanting. Seed with a Poor vigor rating should not
be used at all." |