Submitted to: Crop Science Congress
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/20/1994
Publication Date: N/A
Citation: Interpretive Summary: Alfalfa is the most important forage crop in the U.S. Annual Medicago are closely related to alfalfa and may be useful as new forage crops, cover crop and green manures. The U.S. collection of annual Medicago species is composed of 36 species and a total over 3000 accessions. This germplasm source has been under utilized due to our lack of agricultural knowledge, thus a core subset of this collection was assembled. Based on agronomic characters, we assembled a core subset in 1993. The core subset is a small subset of the total collection which contains most of the variability which exists in the total collection. The core collection is intended for use across the ies with various environments. The core collection was evaluate U.S., thus it was important to study the interaction of the species with various environments. The core collection was evaluated for four agronomic characteristics at six locations: Arizona, Georgia, Maryland, Minnesota, New York, and Utah. The differences wer observed were determined to be du mainly to the environments which the plants were grown in. Some species showed promising agronomic potential. However, some of the annual Medicago species varied in their stability in different locations, suggesting or regional basis. This core collection and this research will be useful to agronomists who are interested in new plants which can be used as a cover crop, green manure, and/or companion crop will be interested in use of these annual Medicago species.
Technical Abstract: The annual Medicago core collection that was assembled based on phenotypic diversity of 14 traits evaluated in Maryland is intended to be used across the U.S. Therefore, it is important to study the genotype X environment interaction patterns and agronomic potential of the core collection across diverse environments in the U.S. In this study, the core collection was evaluated for four agronomic traits; spread, height, days to flower, and pod production at six locations: Arizona, Georgia, Maryland, Minnesota, New York, and Utah. An Additive Main Effects and Multiplicative Interaction model was used to study the cause of the genotype X environment interaction. The genotype X environment interaction was due mainly to differences among environments, and not species. Some species showed promising agronomic potential. However, the annual Medicago species varied in their stability across environments, suggesting that species suited for cultivation should be selected on a location or regional basis. The results of this study indicate that the core collection would have had a different composition if assembled on phenotypic evaluations in another location. In the future, genetic evaluations of the core collection to supplement the existing phenotypic evaluation should improve the core collection.