Differential concentration of ten minerals among four ancestral alfalfa germplasms

Rapid expansion of dairy herds in the southwestern USA has increased the need for high-quality alfalfa (Medicago sativa L.) forage in the region. Enhancing mineral balance in alfalfa forage could benefit both plant and animal production. The objective of this study was to survey four ancestral alfalfa germplasms (representing the range in fall dormancy) for variability in shoot mineral concentration and for phenotypic associations among mineral concentrations. African, Chilean, Flemish, and Ladak germplasms, and the check cultivar Moapa 69, were evaluated in a 2-yr irrigated field study near Las Cruces, NM. Plots consisted of 12.2-m-long raised beds spaced 1.2 m apart. Plant spacing within plots was 0.26 m. Ten plants per plot were randomly sampled in the early-bud stage in 1993 and the late-bnd stage in 1994 and evaluated for P, Ca, S, Mg, K, Na, B, Cu, Fe, and Mn concentration using an inductively-coupled plasma spectrometer. Years were a significant source of variation for all minerals except Mn, while the population × year interaction was significant for P, Ca, Mg, S, and Mn. The more dormant germplasms, Flemish and Ladak, generally had the highest P and K concentration and the lowest Ca concentration in both years. Flemish germplasm also possessed relatively high concentrations of S, Na, Fe, and Mn. A greater proportion of significant phenotypic correlations between minerals were observed in this study than in previous reports. These results suggest that Flemish-based parental populations should provide useful genetic materials for enhandng mineral concentration in alfalfa forage.