Plant breeders can obtain six new germplasm lines of guayule, a rubber-producing crop that could provide additional income for farmers in the arid and semiarid Southwest. The lines were selected by Agricultural Research Service scientists for high yield and uniformity, two important traits that current varieties lack.

Like current lines, the new ones can be harvested twice. But the first harvest of some of the new releases can be at age 2 years, a year sooner than today’s available plants. Only the branches are picked at the first harvest; the whole plant is processed at the second harvest.

The new germplasm lines, named AZ-1, AZ-2, AZ-3, AZ-4, AZ-5 and AZ-6, were developed from earlier selections by researchers at the University of Arizona in the early 1980's. Each new breeding line conveys important traits for guayule. For example, AZ-2 when 2 years old is twice the size of some current varieties when they’re 3 years old. Others of the new lines yield two times more rubber than older varieties.

Guayule has the potential to become a domestic source of natural rubber, for which there is ever-increasing demand. Continued exposure to surgical gloves made from natural rubber from the tropical Hevea tree causes allergic reactions among many doctors, nurses and other health practitioners. Products from guayule rubber do not cause these allergic reactions.

Limited quantities of seed are available to researchers and plant breeders developing commercial guayule varieties.

Scientific contact: David A. Dierig, ARS U.S. Water Conservation Laboratory, Phoenix, Ariz., phone (602) 379-4356, fax (602) 379-4355, ddierig@uswcl.ars.ag.gov.