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United States Department of Agriculture

Agricultural Research Service

Alfalfa

Alfalfa

Alfalfa is the fourth most widely grown crop in the United States, with an estimated annual value of 11.7 billion dollars. There are 26 million acres cut for hay with an average yield of 2.3 tons per acre. One of the most important characteristics of alfalfa is its high nutritional quality. Alfalfa contains between 15 to 22% crude protein as well as high amounts of 10 different vitamins. Alfalfa can be a very productive crop with high levels of biomass accumulation. The record yield of one acre of alfalfa is 10 tons. Alfalfa hay is used as a feed primarily for dairy cows but also for horses, beef cattle, sheep, and other farm animals.

Molecular Genetics:
1. Development of SSR DNA markers appropriate for mapping of alfalfa, through development of genomic DNA libraries and screening alfalfa genomic clones, mining data bases of Expressed Sequence Tag (EST) and Bacterial Artificial Chromosomes (BAC) library databases for SSRs from Medicago truncatula. (List of genomic SSRs).
2. Evaluation of diversity and phylogenic relationships among and between Medicago sativa subspecies and related Medicago species including the model legume M. truncatulausing SSR markers to develop SSR marker subsets for differentiating selected alfalfa cultivars and populations. (See Results of Nine Historic Alfalfa Germplasm Sources).
3. Development of SSR-based maps of alfalfa and mapping of markers to appropriate linkage groups, and integrating them with previously mapped Amplified Fragment Length Polymorphism (AFLP) and Restriction Fragment Length Polymorphism (RFLP) markers. (See map)

Alfalfa Cytogenetics:
Cytogenetics involves the study of chromosomes. Chromosomes contain the hereditary information of the cell. Genes are located on chromosomes, thus, it is important to study the structure and behavior of chromosomes to understand the inheritance of a trait. Alfalfa (Medicago sativassp. sativa (L.) L. & L.), a tetraploid (2n=4x=32), is the most important forage crop grown in the North America. Despite its importance to U. S. agriculture, cytogenetic research on alfalfa and its closely related species has lagged far behind other crops mainly due to four difficulties. We have been able to overcome some of these difficulties.

Annual Medicago species
What are annual Medicagospecies? They are legumes, related to alfalfa. They are sometimes referred to as medics. They are true annuals, they flower, set seed and die within one growing season. They are all self-pollinating, therefore bees are not required to produce seed. They are native to the Mediterranean region of the world. The U. S. National Plant Germplasm System contains 3159 accessions of annual Medicagospecies, this collection includes 35 different species. We have been working on the concept of developing core germplasm collections for their increased use. Recent interest in cropping systems with a sustainable agriculture approach has placed renewed interest on legumes. There are several examples how the annual medic maybe used in sustainable agriculture systems. throughout the U. S.

 


Last Modified: 6/21/2010
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