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.”
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 test. 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 of 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.”