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High hopes for seeding guayule.

High Hopes for Seeding Guayule

Home-grown guayule, a native shrub that produces natural rubber, would reduce our dependence on imports of this critical material while boosting farm income in the southwestern United States. This 3-foot tall, drought-tolerant shrub, pronounced why-YOU-lee, grows wild in southwestern Texas and northern Mexico.

The surest way to get a field of guayule established is to transplant seedlings that were started in greenhouses. But while this expensive, labor-intensive planting technique is practical for high-value crops like tobacco, it's not economical for domestic rubber production.

Agricultural Research Service scientists in Arizona developed a seeding technique that produces stands that are more uniform, with seedling growth more vigorous, than ever before. The technique promises to make guayule more competitive as a new crop for U.S. growers.

"Compared to scattering seed on the soil surface, we can get 10 times more seedling survival with our method, and it's now practical on a large scale," says Francis S. Nakayama, a chemist at the U.S. Water Conservation Laboratory, Phoenix, Arizona.

First, the seeds are pre-treated with a combination of polyglycol, growth regulator, and fungicide. Then a commercially available planter seeds them to a depth of one-quarter to one-half inch. The seed treatment procedure was developed by Ganapathy R. Chandra at the Plant Hormone Laboratory in Beltsville, Maryland.

"Seeds planted one-quarter-inch deep can be covered with soil, while a thin covering of vermiculite works better for the deeper planted seeds. This is presumably because vermiculite presents less resistance to emerging seedlings than the soil covering," says Nakayama.

ARS scientists worked with collaborators from state agricultural experiment stations of the University of California, Texas A&M University, New Mexico State University, and the University of Arizona to breed improved guayule plants. They have succeeded in doubling natural rubber production from about 500 pounds per acre per year for native plants to 1,000 pounds for the new breeds.

These advances will help make guayule a commercial crop that can compete with natural rubber harvested from trees in southeastern Asia. It would also be an alternative crop for farmers in southwestern states under both irrigated and dryland farming operations.

Producing natural rubber in the United States would lessen our reliance on imported rubber and ensure steady supplies of this vital industrial raw material. Climatic or political changes overseas might affect imported rubber's availability and price.

Some economic studies indicate that there will be a natural rubber shortage worldwide by the mid-1990's and certainly by the turn of the century. Today's popular radial tires require more natural rubber than older bias-belted types. Aircraft tires, which operate under high temperatures and impacts, require almost 100 percent natural rubber.

Natural rubber is a renewable resource while synthetic rubber is manufactured from petroleum--a resource that is steadily being used up.

Francis S. Nakayama is at the USDA-ARS U.S. Water Conservation Laboratory, 4331 E. Broadway, Phoenix, AZ 85040. Phone (602) 379-4356.

PHOTO : Harvesting guayule. (K-1557-7) Below: Rubber extracted from dried guayule plants. (K-1633-1)
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Title Annotation:research on farming guayule, natural rubber producing shrub
Author:Senft, Dennis
Publication:Agricultural Research
Date:Aug 1, 1991
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