Physiological and Morphological Characterization of Basalt Milkvetch (Astragalus filipes): Basis for Plant Improvement

Astragalus filipes Torr. ex A. Gray (basalt milkvetch or threadstalk milkvetch) is a legume that is widely distributed in western North Americaandholdspromise forrevegetationandrestorationprograms inthewesternUnitedStates.Seedof67accessionswascollected in2003 from Utah, Nevada, Idaho, Oregon, California, and Washington. Field-collected forage samples from these accessions had nondetectable or low levels of selenium, swainsonine, and nitrotoxins. Accessions were evaluated at Providence and Millville in northern Utah in 2005 and 2006. At Providence accessions from north-central Oregon exhibited comparatively high biomass yield in summer and fall during both years. Basalt milkvetchaccessionswith lowbiomassgenerallyhadhighcrudeprotein concentration.Acid-detergent fiber andneutral-detergent fiber were positively correlated with biomass yield (r50.42, P,0.0001; r50.57, P,0.0001, respectively). At Millville accessions from northcentral Oregon exhibited comparatively high biomass and seed yield. Seed weight per 100 seeds varied among basalt milkvetch accessions in bothyearsatMillville.PlantsatMillville treatedwith imadicloprid insecticidehadgreater seedyields thannontreatedplants in2006,butnot in 2005. When averaged across sites and years, a high correlation between number of stems and biomass (r50.82, P,0.0001) indicated that numberof stems isa reliablepredictorofhighbiomassandseedyield.Principalcomponentanalysisof sevenconsolidatedplant traits identified two principal components that accounted for 60% and 15% of the variation among accessions. The first principal component was negatively correlated with elevation (r520.71, P,0.01) and positively correlated with latitude (r50.46, P,0.01). The second principal component was positively correlated with elevation (r50.36, P,0.01) and negatively correlated with latitude (r520.47, P,0.01). These results are beneficial in identifying basalt milkvetch accessions that hold promise for plant improvement efforts.