Breeding strategies in Melilotus albus Desr., a salt-tolerant forage legume

Melilotus albus Desr. is recognized as one of the species with greatest potential as a forage source for ruminants in saline rangelands. The objectives of the current research were threefold: (1) to estimate heritability and genetic correlation of traits associated with winter forage production and regrowth capacity in M. albus prebreeding material, as measured in spaced plants grown in a nonsaline environment; (2) to evaluate winter forage production of a selected population grown in plots at sites with contrasting soil salinities; and (3) to evaluate the agronomic performance of blended (mixed) populations and monocultures of M. albus grown in plots. Results indicated presence of genetic variability associated with winter production and regrowth capacity in a prebreeding population selected for one trait, viz. late flowering. Results also showed that selection in a nonsaline environment did not modify the relative salinity tolerance of M. albus populations. Finally, varietal mixtures (blends) of two selected populations showed a slight increase in and more seasonally balanced dry matter (DM) yield than monocultures. Mixtures combined favorable characteristics from the two selected populations (i.e., highest winter forage production, as expressed in the SP1 population, and highest regrowth capacity, as expressed in the SP2 population). Furthermore, results indicated that M. albus genotypes naturalized in Argentina could be used as genetic resources for sweet clover breeding for saline environments and that alternative breeding approaches could improve forage productivity in saline environments.