Is there an optimum size for cotton seed?
Dr. Kater Hake, vice president, Agricultural and Environmental Research, Cotton Incorporated, kept an eye on the exit door while delivering his presentation on cotton seed size and quality at the recent Southern Cotton Ginners Association meeting in Branson, Mo. He was painfully aware of how contentious the issue of smaller cotton seed has become throughout the ginning community.
The size of cotton seed (planting seed) has progressively gotten smaller since 2002 when Deltapine 555 dominated with a 17 percent market share. “The size of planting seed has most definitely decreased,” says Dr. Fred Bourland, professor, Northeast Research and Extension Center, University of Arkansas, and veteran cotton breeder. “Several of the predominately planted varieties today have seeds that weigh under 9 grams per hundred seeds.”
Cotton producers need seed with a high “percent field emergence” rating. “If a bag of cotton seed has that good rating, it can be planted under cooler temperatures and the chances of getting a viable stand are greatly increased,” says Hake. “Last year was extremely tough for seed production, especially in West Texas. High winds and rain made for an overall bad planting season and poor seed production year.”
Referencing a slide showing how the polar vortex and jet streams cycle around the globe, one of Hake’s take-home messages to the group of ginners (many who are also cotton producers), was to gain a more in-depth understanding of weather patterns to improve their ability to manage each year’s cotton crop.
World carbon levels are increasing. Weather tools and the data they gather have improved significantly over the last decade. “Weather on our planet is changing each year,” says Hake. “This year, France was 16 degrees hotter than the 30-year baseline for that region. The weather event made national news.”
Hake encouraged everyone to sign up for the weekly weather forecast available via Cotton Incorporated’s “Cotton Cultivated” website: https://cottoncultivated.cottoninc.com/.
For every centigrade the ambient temperature increases, the air is able to hold 7 percent more moisture. “It’s the uncertainty of getting that hot temperature wave that comes and goes that makes it so difficult to manage a cotton crop each year,” says Hake.
Using the analogy of going to the doctor and asking questions about your own health, Hake urges all farmers to become better consumers when it comes to making their annual seed purchases. “After planting, ask your seed salesman questions if seed from the same seed lot perform differently in the field,” says Hake.
Germination, oil content, and seed size
A 2014 article published in the Journal of Science by John L. Snider and a few other collaborators substantiated the strong relationship between seed size, seed oil content, and the role each plays in seedling vigor.
“The announcement will be made during this year’s Cotton Breeders Tour (July 22-25) that Cotton Incorporated will begin measuring seed oil content for all cotton breeders in both public and private sectors who would like to take advantage of the service,” says Hake. “We hope to increase awareness within the breeder community about the importance of oil content in cotton seed.”
Cotton producers have learned that indeterminant varieties give them the upside potential of another half-bale from the top crop for no additional cost other than protecting the fiber from insects. “With bigger seeds we’ve given up some of that indeterminant stress tolerance,” says Hake. “Deltapine 555 took it to the extreme. There were some pipeline varieties never even commercialized because of their potential for excessive growth. Triple Nickel wouldn’t have been commercialized had it not been for PIX.”
Smaller seeds have been the easiest way for breeders to increase “per-seed” fiber production. “Smaller seeds are more indeterminant and mid-season stress tolerant,” says Hake. “Larger seeds also bring on higher harvesting, hauling, and module wrap costs. This has to be part of the discussion.”
Sugars from a cotton plant are used to make fiber, almost on a 1-to-1 basis. “For those sugars to be converted into oil, you will lose almost half the value of the sugar because, physiologically, that sugar has to be broken down into smaller pieces and then built back up,” says Hake. “It takes twice as much plant sugar to make a pound of oil.”
Surprisingly, the production of plant proteins takes the most of a plant’s energy. “It’s a much more complex process,” says Hake. “You have to start with nitrate from fertilizer in the soil. Then this is built into ammonia, amino acids, and proteins. If we have to choose, let’s make fiber and oil.”
Gene editing, broader discussion
Cotton Incorporated is funding projects to increase the fiber density per-seed and increase oil content through CRISPR technology. “Gene editing is a powerful tool and this technology allows scientists to selectively modify a plant’s gene, activating or eliminating a specific function,” says Hake. “If you don’t want the plant to do something, you make the edit and in the process of the plant repairing itself, that specific gene becomes non-functional.”
Most of the world, especially Europe, has a moratorium on CRISPR technology. The U.S. and Australia are the only two cotton-producing countries that are open to its use.
One of whole cottonseed’s end-use markets has been the dairy cow industry. They have been supplementing oil in their cattle rations for years. “A higher percentage of oil in whole cottonseed would increase its marketability and help drive the economics of the crushing industry and whole cottonseed’s use by dairymen,” concludes Hake.
Hake closed out his presentation by sharing a comment made by Campbell, Mo., ginner David Blakemore who said, “We need to think about the issue of cotton seed size from the viewpoint of what benefits the most segments in our industry, or the most people, or improves the value for all.”
