Pop Goes the
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 theres
no pollen available to pollinate the cotton flower, and thats why
sprinkler water or rain can quietly slash a farmers 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
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 waters 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)