Alfalfa Meets Its Asian Relatives

By Jan Suszkiw
January 3, 2001

Hardy new alfalfa cultivars that tolerate drought, frequent grazing, poor soils and other crop stresses may come from four germplasm lines that Agricultural Research Service scientists developed from the legume's wild Asian relatives.

Commercial cultivars bred from this germplasm could help broaden alfalfa's range and productivity as a cut-hay crop or grazing-type forage, particularly on dry rangeland typical of western states like Oklahoma, Montana and Nevada.

The wild alfalfa relatives also have potential as a new stand-alone legume crop in these areas, according to Austin Campbell, an agronomist at ARS' Soybean Genomics and Improvement Laboratory in Beltsville, Md.

In addition to hay, valued at an estimated $8.1 billion annually, alfalfa is a popular cover crop since it helps improve soil fertility by "fixing" nitrogen from the air. The legume's flowers also are a favorite nectar source for bees.

To improve the crop's stress tolerance and adaptability, Campbell turned to Medicago ruthenica L., a distant relative of today's cultivated alfalfa. M. ruthenica is an ancient but durable legume from the desert steppes, volcanic soils and grassland regions of Siberia, Tibet, Mongolia and China.

During the past decade, Campbell, Larry Teuber of the University of California at Davis, and the late Danny Mowrey of ARS traveled to Inner Mongolia to bring back 100 plant specimens, called "accessions," for preservation in the U.S. National Plant Germplasm System maintained by ARS, the U.S. Department of Agriculture's principal scientific research agency.

Campbell says germplasm lines MR2-SYN1, MR3-SYN1, MR4- SYN1 and MR5-SYN1 are their "top picks." Last fall marked their first-ever release in the form of seeds sent to more than 100 universities, commercial seed companies and other organizations around the world. This followed nine years of plant breeding and evaluation to improve the wild alfalfa for desirable traits including dense, upright growth, early flowering, seedling vigor and leaf hopper resistance.

In one field trial, for example, MR4-SYN1 scored higher on leaf hopper resistance than the other three lines, including WL316, a commercial variety with leaf hopper resistance.

Scientific contact: Austin Campbell, ARS Soybean Genomics and Improvement Laboratory (formerly Soybean and Alfalfa Research Lab), Beltsville, Md., phone (301) 504-5638, fax (301) 504- 5167, campbela@ba.ars.usda.gov.