Morphological and physiological variation among ecotypes of sweetvetch (Hedysarum boreale Nutt.)

Abstract

This study considered seedling establishment characteristics, nitrogen fixation capability, nutritive value, and clustering relationships among 11 putative ecotypes of sweetvetch (Hedysarum boreale Nutt.). A total of 44 morphological and physiological variables were evaluated in greenhouse and field experiments. Sweetvetch root systems had large nodules that were capable of fixing nitrogen, a potentially useful attribute in the reclamation of nitrogen-limited environments such as mine spoils in the western United States. Sweetvetch provided forage during the spring and summer, but little forage was available during the fall and winter. An ecotype collected near Orem, Utah, exhibited superior seedling establishment characteristics under mesic conditions while an ecotype from near Duchesne, Utah, established well under xeric conditions. An ecotype from Hobble Creek, Utah, showed superior rhizome development, a potentially useful characteristic for stabilizing highly erodible areas. Although cluster analysis procedures indicated differences among the ecotypes, this clustering was not always clearly related to characteristics of the collection site. Sufficient genetic diversity was present among ecotypes to assure adaptation to a wide array of sites and to facilitate improvement through breeding and selection.