1996 Alfalfa Crop Germplasm Committee Report


Alfalfa (Medicago sativa L. sensu lato) is the most important forage legume species in North America. The area of alfalfa cut for hay in the U.S increased from a few ha in the mid-1800s to a peak of 12.1 million ha in 1958. Since 1980, the area has varied between 10.5 and 10.9 million ha. The crop has an estimated market value of about $7.5 billion. Compared with all other crops, alfalfa is recognized as the most:

In addition, alfalfa is an excellent source of vitamins and minerals for all classes of livestock and is important for improving soil tilth. It also serves as a model system in many types of forage crop research and for the study of autotetraploid inheritance (Barnes et al., 1988). Many annual species in the genus Medicago serve as important components in pastures in regions with Mediterranean climates. Potential use of annual Medicagos in the U.S. remains to be determined. However, they may be particularly well suited for use as pasture, green manure, and cover crops in sustainable agricultural systems.


Origins of alfalfa and its early introductions in North America

Alfalfa originated in Vavilov's "Near Eastern Center"--Asia Minor, Transcaucasia, Iran and Turkistan. In the wild, M. sativa and related perennial species are found throughout Eurasia and as far north as Siberia. Alfalfa spread from its center of origin into Europe, North Africa, Arabia and eventually South America with invading armies, explorers, and missionaries as feed for horses and other livestock. In 1736, European colonists brought alfalfa to the eastern U.S. where the crop was referred to by its European name, lucerne. These introductions generally were not successful, except for a few planted on well-drained limestone soils. Alfalfa was well suited to the dry climates and irrigated soils of the western U.S., where it was introduced from Mexico by Spanish missionaries as early as the 1830s. Alfalfa eventually spread eastward to the Intermountain region and the southern Great Plains. Movement into areas with severe winters was limited by the lack of hardiness in the primarily Spanish-derived germplasm. The introduction of winter-hardy types from northern Europe to the North Central States in the 1850s allowed successful alfalfa culture in the colder and more humid areas of the midwestern and northeastern U.S.

Plant introduction and alfalfa improvement

From alfalfa's initial introduction until 1955, about 33 recognized alfalfa cultivars or regional strains were grown in the U.S. and Canada. About half of these were directly introduced from Europe, Asia or the Near East. Between 1958 and 1991, organized alfalfa breeding expanded tremendously and the number of recognized cultivars increased to about 400. Before 1925, most alfalfa breeding efforts in North America were directed toward selecting strains that were more winterhardy. During the next 30 years, emphasis was placed on developing cultivars that combined winterhardiness and resistance to bacterial wilt. During the late 1950s, the emphasis was placed on developing cultivars resistant to other diseases and several insect pests (Barnes et al., 1988).

A trend toward increased genetic diversity in alfalfa cultivars, spurred largely by breeding efforts begun in the 1950s, and the inherent genetic heterogeneity of the species has made alfalfa less vulnerable to catastrophic loss than it was 50 years earlier. Nevertheless, relatively few individual sources of germplasm have been exploited in alfalfa breeding and genes from a single accession have frequently been used repeatedly. For example, a single introduction (PI 20725) is represented in at least 30 distinct, and widely grown cultivars (Rumbaugh, 1991). All basic germplasm used in the development of present North American alfalfa cultivars can be traced to one or more of nine primary regional germplasm sources (Barnes et al., 1977). However, several of the nine regional sources have been represented by very few introductions. Most notable in this regard is the predominance of a small number of closely related 'African' and 'Indian' introductions within elite nonhardy cultivars (Smith et al., 1991). Furthermore, in some regions sources of exotic alfalfa germplasm, which may be useful in plant breeding, are subject to loss due to the importation of elite cultivars, principally from the U.S. (Marble, 1989).

Annual species of Medicago--the "medics"

The genus Medicago also includes many lesser known, but potentially useful annual species. Members of the 29 annual Medicago species, commonly known as "medics", are receiving more attention with the emphasis on more sustainable agricultural systems. Medics are native to semiarid areas around the Mediterranean Sea and have long been used in unimproved pastures in the region. Many medics are now widely distributed throughout the world, largely in areas with mild, rainy winters and alkaline soils. In these regions, medic seeds germinate in late fall with the onset of winter rains, grow vegetatively until early spring, and then flower and produce seed in late spring before the plant dies. Hardseededness is common in medics reducing premature germination during summer months. Many medics are tolerant of grazing and can produce multiple forage crops in a single season. Medics have been extensively utilized in Australia and are grown on about 50 million ha there (Crawford et al., 1989). Medics have been most successful in cereal-legume crop rotation systems in southern Australia where winter rainfall averages between 250 and 500 mm. Certain medics have also been used in revegetation, intercropping, hay production or as green manures. The U.S. PI collection now contains over 2000 accessions of annual medics. These introductions originate from a wide variety of environments and represent a tremendous source of potentially useful plant materials for use in sustainable agriculture.


The roles of public and private alfalfa researchers

The rate of release of new alfalfa cultivars in the U.S. has increased steadily over the last 90 years. About one cultivar was released every three years between 1901 and 1940; one each year between 1941 and 1960; about 17 per year between 1981 and 1985; about 30 each year between 1985 and 1990; and about 60 per year between 1990 and 1995. Since their inception in the mid-1950s, private alfalfa breeding programs in the U.S. have been responsible for the rapid increase in numbers of recognized alfalfa cultivars. During the period between 1955 and 1960, approximately 20% of cultivars were released from private breeding programs. This proportion increased to more than 95% between 1985 and 1990. Private breeding programs increased in number, size and sophistication from about 1965 to 1985. During the late 1980s, competition for market share caused several mergers within the private sector. At present, there are about 8 commercial alfalfa breeding programs with annual research expenditures ranging from about $100,000 with 1.0 scientist-year (SY) to more than $2 million with five or more SYs.

Increased breeding by industry was accompanied by a reduction in the number of public breeding programs, and by a change in the direction of public research from breeding new cultivars to developing new breeding procedures and improved germplasm (Barnes et al., 1988). The transition from applied alfalfa breeding to more fundamental research within public agencies contributed to the development of several comprehensive research efforts. Examples of research areas include: study of the morphology and anatomy of alfalfa as it relates to productivity and persistence, improvement of nitrogen fixation, improvement in grazing tolerance, transfer of genes between ploidy levels and Medicago species, development of methods to maximize heterosis for yield, improvement of forage quality by improving nitrogen concentration in the forage, elevating insect resistance by using novel methods of insect inhibition, development of genetic maps using molecular genetic markers, description of phenotypic and genetic relationships between different alfalfa germplasm sources, transformation of alfalfa with foreign genes, and use of tissue culture in selection programs. More generally, public researchers working with alfalfa also continue to provide valuable knowledge in plant genetics, physiology, and growth, including resistance to biotic and abiotic stresses.

The increase in private commitment to alfalfa improvement has been associated with a concomitant the decline in the number of public alfalfa researchers. The wide acceptance of the best proprietary cultivars by the 1980s confirms the efficacy of private breeding programs, and suggests that an appropriate balance has been reached between fundamental public research and more applied private research. However, the balance between public and private programs may now be in danger because of recent reductions in support for public alfalfa research programs. The termination of a number of public alfalfa breeding and genetics programs also means that many breeder's germplasm collections may be subject to loss.

Increasing the use of medic germplasm

Annual Medicagos have not been used as intensively in agriculture in the U.S. as in Australia or the Middle-East. Naturalized medics are most common in California where ecotypes of M. polymorpha, known locally as bur clovers are most frequent. They fix nitrogen and produce high protein forage on many winter rangelands in some of the drier areas of the state. Bur clovers are also found in the pastures of east and central Texas and southern Oklahoma. The medic species M. orbicularis (button clover) and M. arabica (spotted bur clover) have been introduced into the southeastern U.S. where they were overseeded into grass pastures. Research in Montana and Utah indicates that certain medics such as M. lupulina may also hold promise as summer annuals on pastures and rangelands in the Great Basin (Rumbaugh and Johnson, 1986). A cultivar of M. lupulina has been released by the Montana State Agricultural Experiment Station (Sims et al., 1985). The use of annual medics as summer green manure crops has been investigated extensively in the north central and northeastern US since the early 1990s.

Over 20 medic cultivars from seven different species have been released by Australian plant breeders. Their improvement has focused on earlier flowering, reduced pod spininess, increased forage and seed production, and tolerance to insects. Intensive efforts have also been directed toward the development of medics and their associated Rhizobium bacteria. While medics cannot be directly hybridized with their perennial relative alfalfa, research on transferring certain traits, such as resistance to some insects from medics to alfalfa is also now underway. Until the early 1980s, relatively little research has been conducted with annual Medicagos in the U.S. The ACGC is actively working to promote the recognition and use of medics, especially as part of sustainable agricultural systems. A short article describing the range of variation in the medics and their possible uses was distributed by the ACGC in early 1991 and has appeared in various publications oriented toward farmers and ranchers.


The present ACGC committee contains 20 members fairly equally divided between the public and private sectors (Appendix A). From 1991 to 1995, Steve Smith served as chair. Joe Bouton is the current chair.

In 1976, the U. S. PI collection had about 900 accessions of Medicago sativa and M. falcata plus several hundred accessions of annual and related perennial Medicago species. At that time there was no systematic plan for seed increase under isolation and most evaluations were made with open-pollinated seed. There was no national program for germplasm evaluation or germplasm enhancement and few plant breeding programs were concerned with using P.I.'s. Since then, alfalfa scientists individually and collectively with the NPGS have developed a functional system for germplasm collection, maintenance, and evaluation. Most parts of the system are now in place. ACGC's present concerns involve refinement of the collection as well as preservation and evaluation of parts of the system, and development of a germplasm enhancement program to make basic germplasm more useful to the alfalfa research community.

Collection Management

Plant exploration and collection trips made by D. Johnson and D. Sheely to Mongolia and by Stephanie Greene et al. to the North Caucasus Mountains, Russia resulted in the addition of several new accessions of both perennial and annual Medicagos.

These recent acquisitions have increased the collection to about 2936 accessions of perennial Medicagos and 2613 accessions of annual Medicagos (Appendix B). Since one of the committee's main objectives has been to regenerate seed of each of these accessions in cage isolation (e.g. to move away from open-pollinated seed), a current inventory shows that only 417 accessions of perennials and 406 accessions of annuals still require this type of seed increase (Appendix B).

Medicago accessions were distributed as follows:

		 FY1991	FY1992	FY1993	FY1994	FY1995	

Perennials		2139	1520	1409	1016	2518
Annuals 2858 1780 1079 991 1319

With the recent evaluations for ruminal protein degradation, unifoliolate internode length, and tolerance to lygus, Sclerotinia, and acid soils, data are now available in the Germplasm Resources Information Network (GRIN) for over 35 agronomically important traits for the core collection, and for many traits, a large portion of M. sativa accessions in the collection. Basic agronomic data on annual medics are also available from seed increase plots as well as the addition of anthracnose evaluation on the annual core collection.

Evaluation Proposals

The committee decided to solicit and fund proposals on evaluation of the collection from the alfalfa community. In the initial year (1995), 14 proposals were received. Nine reviewers were selected from the committee with a majority of these from the alfalfa seed industry. The top 4 proposals were funded and included enhancement of Medicago germplasm for resistance to multiple virulence phenotypes of Aphanomyces root rot, enhancement of M. falcata germplasm for use in cultivar development, measuring genetic distances among accessions in the core collection, and evaluation of the collection for glandular trichome density and alfalfa weevil resistance. The committee plans to continue this "granting" program for the immediate future.


Dr. Stephanie Greene began as Alfalfa Curator at Pullman in January 1995. Dr. Greene will concentrate on regeneration and curatorial activities along with organization of evaluation data, user support and research on regeneration techniques. An immediate goal was to update and clarify the accession histories so duplicate accessions may be eventually eliminated. To date, 12,000 accession histories have been completed, and of these, 500 have been entered into GRIN. Once completed, the GRIN data base will be carefully reviewed for duplication based on accurate passport information. Dr. Greene expects to complete this project by the end of 1996.


One of the ongoing objectives of the ACGC is to improve the user community's understanding of the resources held within the collections. In 1993, ACGC developed and distributed the first Medicago Germplasm Newsletter to members of the NAAIC in the U.S (Appendix C). The costs of the bulk mailing were covered by the NAAIC. A second volume of the newsletter was produced and distributed in 1994 and the committee plans to continue this activity in the future.


The current PI collection of perennial Medicago species is large and few accessions have many of the basic traits necessary in current varieties. The disparity in pest resistance between current alfalfa cultivars and essentially all PI's makes the use of the collection difficult in applied alfalfa breeding. Recognizing this, the ACGC has in the past considered funding development of regional and national germplasm pools for perennial Medicagos utilizing both plant introductions and elite germplasm (see 1991 report). Budget constraints and the lack of this objective being a high priority for the committee resulted in the enhancement plan never being implemented. However, this will be changing with the funding of two proposals concerning enhancement (see Evaluation Proposals section above) and indicates the alfalfa community considers specific enhancement proposals more desirable and workable than development of regional germplasm pools.

The ACGC has not developed an enhancement plan for the annual Medicagos.


1. Continued funding for the alfalfa germplasm CRIS project at Pullman, WA for the preservation of the current Medicago collection with annual assignment of activities by the ACGC and for continuation of the current evaluation "granting" program with an increased emphasis on the development and refinement of core collections .

2. Implement a germplasm enhancement plan that includes participation by public and private breeding programs.

3. Develop a thorough exploration and collection plan based on recognized deficiencies in the U.S. PI collection and other collections including standards to reduce redundancy.

4. Generate a plan to catalog and facilitate the distribution and preservation of germplasm held in breeder's programs that are being discontinued.

Considering the funding currently available from the USDA for alfalfa germplasm preservation and evaluation research, it seems unrealistic to request new funds. However, the committee is greatly concerned with the transfer of the Trifolium collection to Pullman without the funds normally associated with the Trifolium collection. This move effectively reduces the budgets available to manage and evaluate both collections. Therefore, ACGC considers restoration of these moneys to be critical in order to properly manage, evaluate, and enhance both the Medicago and Trifolium collections.


Barnes, D.K., B.P. Goplen, and J.E. Baylor. 1988. Chapter 1: Highlights in the USA and Canada p. 1-24. In A. A. Hansen, D. K. Barnes, R. R. Hill, Jr. (ed.) Alfalfa and Alfalfa Improvement. ASA/CSSA, Madison, WI.

Barnes, D.K., E.T. Bingham, R.P. Murphy, O.J. Hunt, D.F. Beard, H.H. Skrdla, and L.R. Teuber. 1977 Alfalfa germplasm in the United States: genetic vulnerability, use, improvement, and maintenance. USDA Tech. Bull. 1571. U. S. Government Printing Office, Washington, D. C.

Crawford, E.J., A.W.H. Lake, and K.G. Boyce. 1989. Breeding annual Medicago species for semiarid conditions in southern Australia. Adv. Agron. 42:399-437.

Guarino, L. 1990. Alfalfa collecting in southern Arabia. Plant Genetic Res. Newsl. 80:33-35.

IBPGR. 1985. Forages for Mediterranean and adjacent arid/semi-arid areas. Report of a working group, April, 1985. IBPGR Secretariat, Rome.

Marble, V.L. 1989. Fodders for the Near East: Alfalfa. FAO Plant Prod. and Protect. Paper 97/1. FAO, Rome.

Rumbaugh, M.D. 1991. Plant introductions: The foundation of North American forage legume cultivar development. p. 103-114. Use of Plant Introductions in Cultivar Development, Part 1, CSSA Spec. Pub. no. 17.

Rumbaugh, M.D. and D.A. Johnson. 1986. Annual medics and related species as reseeding legumes for northern Utah pastures. J. Range Manage. 39:52-58.

Sims, J. R., S. Koala, R. L. Ditterline, and L. E. Wiesner. 1985. Registration of 'George' black medic. Crop Sci. 25:709-710.

Smith, S.E., A. Al-Doss, and M. Warburton. 1991. Morphological and agronomic variation in North African and Arabian alfalfas. Crop Sci. 31:1159-1163.

Updated June 24, 1996.