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Pop Goes the Cotton!
By Don Comis
June 11, 2001
How is a cotton field like a bowl of crispy rice cereal? Answer: When cotton pollen grains get wet, they react much like crispy cereal in milk--the grains swell up and pop open. They dump their contents, resulting in the death of the pollen grain. That means there’s no pollen available to pollinate the cotton flower, and that’s why sprinkler water or rain can quietly slash a farmer’s annual cotton yield.
This lost potential all happens in a single day, because that is all the time a cotton flower has to pollinate. When enough pollen gets wet and explodes, it leaves behind a sterile flower that soon falls off, with no chance of forming a boll loaded with precious cotton fibers.
Agricultural Research Service plant physiologist John J. Burke has peered through a microscope and seen pollen grains literally explode within 30 to 60 seconds of being wet by a drop of water. He also has seen yields of greenhouse cotton plants reduced by 55 percent from just one squirt of water per flower. Burke is with the ARS Plant Stress and Germplasm Development Research Unit in Lubbock, Texas.
With funding from Cotton Incorporated, Cary, N.C., Burke compared conventional overhead sprinkler-irrigated fields with fields watered by "drop socks” attached to sprinklers close to the ground. Drop socks minimize water sprayed onto plants. Burke found that plants watered by overhead sprinklers lost cotton flowers, resulting in yield reductions of 25 to 36 percent. The solution Burke offers is to water plants from below, through drip, furrow or drop-sock irrigation.
Burke made the discovery of the exploding pollen grains when he tried to cultivate cotton pollen in a liquid solution, to aid his search for genes for more heat-tolerant pollen. The discovery of water’s effects led Burke to develop and patent a way to grow pollen on a solid medium.
ARS is the chief scientific research agency in the U.S. Department of Agriculture.
Scientific contact: John Burke, ARS Plant Stress and Germplasm Development Research Unit, Lubbock, Texas; phone (806) 749-5560, fax (806) 723-5272, jburke@lbk.ars.usda.gov.
