Genetic Variability of Mg, Ca, and K in Crested Wheatgrass

Increasing available Mg in crested wheatgrass (Agropyron spp.) reduce the incidence of grass tetany (hypomagnesemia) in glazing this forage. Raising the Mg levels might be done genetic processes if enough variation in ion concentration in the Agropyrons. The purpose of this study was to determine genetic variation in Mg, Ca, and K concentrations in 2 wheatgrass populations. Parent plants were vegetatively to provide 6 replicates each of 12 clones of crested (A. desertorum) and 16 F3 clones of colchicine-induced A. cristatum X natural tetraploid A. desertorum. Each was selected on a basis of seedling and mature plant vigor,, and seed yield, leafiness, resistance to pests, and response to stress. The 2 populations were grown in separate,-planted nurseries at Logan, Utah. Herbage was harvested at pre-boot and early flowering stage in each of 2 years. Magnesium Ca were determined by atomic absorption and K by emission. A reduced tetany potential (RTP) index for each was calculated as the sum of normalized Mg and (Ca+Mg)/K. Significant (P<0.01) differences for all traits were detected clones in each population. All traits, except K and RTP, closely correlated. Broad-sense heritability values for most ranged from 0.61 to 0.84. Enough genotypic variation existed both populations to warrant breeding lines with higher concentrations Mg and larger RTP values. Such changes could reduce incidence of grass tetany in livestock grazing crested wheatgrass.