Agronomic and morphological diversity of alfalfa germplasm in Mexico.

J.J. Marquez-Ortiz1, G. Nunez-Hernandez1, and S. Salinas-Carmona2

1C.E. La Laguna/INIFAP, Apdo. Postal 247, CP 27000 Torreón, Coah., Mexico.

2Semillas Berentsen, Carr. Panamericana Km. 285, CP 38000 Celaya, Gto. Mexico.

Alfalfa was introduced from Spain to Mexico almost 500 years ago. Barnes et al. (1977), suggested that alfalfa germplasm adapted to Mexico could belong to the Chilean group. Mexican alfalfa landraces have shown good forage yields, persistence, and resistance to specific diseases in their areas of adaptation. The objective of this study was to characterize, compare, and classify alfalfa germplasm available in Mexico according to agronomic and morphological traits.

Forty-one alfalfa genotypes (25 landraces and 16 commercial cultivars) were seeded 1 December 1995 at Matamoros, Coahuila, Mexico under a randomized complete block design with four replications. Plots were 20-cm diameter microplots separated at 75 cm. Above-ground morphological variables measured in 1996 were: stem basal diameter; number of top and bottom internodes per stem; and bottom and top central leaflet width and length. Agronomic variables were: spring, summer, fall and annual average dry matter yield, plant height, and leaf:stem ratio. The variables were analyzed by variance, correlation, principal components, and average linkage cluster analyses to determine differences among genotypes, select classification variables, and determine groups based on similarities among genotypes.

Genotypes had significant effects (P<0.05) on spring, summer, fall, and annual average dry matter yield and plant height, top and bottom internode length, top central leaflet width, top and bottom average leaflet width and leaf:stem ratio. Classification variables used for principal component and cluster analyses were annual dry matter yield, fall plant height, top and bottom internode length, average leaflet width and leaf:stem ratio. Cluster analysis classified genotypes into five germplasm groups: DK-189, Oaxaca, Commercial, Tanhuato, and San Miguelito. In general, these groups coincided with their area of adaptation. Each group showed at least one trait which made them different from the other groups: DK-189=highest leaf:stem ratio, Oaxaca=lowest average annual yield, Commercial=highest yield and internode length, Tanhuato=highest fall plant height, and San Miguelito=intermediate for most traits. These results suggest the presence of significant variation among alfalfa genotypes available in Mexico and that such variation can be classified, at the moment, into five different germplasm groups.

References

Barnes, D.K., E.T. Bingham, R.P. Murphy, O.J. Hunt, D.F. Beard, W.H. Skrdla, and L.R. Teuber. 1977. Alfalfa Germplasm in the United States: Genetic Vulnerability, Use, Improvement, and Maintenance. U.S.D.A. Tech. Bull. 1571. 21 p.

Previous Page