Field Evaluation of the NPGS Birdsfoot Trefoil Collection.

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Birdsfoot trefoil (BFT), a non-bloating forage legume, has potential to improve sustainability of pasture systems in the Eastern Transition Zone (ETZ) of the USA. Tannins in BFT can improve protein utilization efficiency and reduce methane emissions and nitrogen excretion by grazing animals. In a NIFA-funded project (Award No. 2013-67013-21408), we evaluated 132 accessions (25%) of the USDA-NPGS collection at three locations (Logan UT, Lansing MI, and Crossville AL) for growth habit, individual plant dry matter yield, and tannin concentration at a target growth stage of at least 50% flowering. Plant growth habit ranged from prostrate to erect, with a median score corresponding to an intermediate growth habit. Mean and median score were close at all three locations, indicating a symmetrical distribution of growth habit scores. Average plant dry mass (DM) is based on a maximum of 10 plants in each of two blocks per location. The experimental average DM reflected the inherent suitability of a location to support BFT viz. Michigan > Utah > Alabama. Again, mean and median score were close at all three locations, indicating a symmetrical distribution of DM. Tannin concentration determination has been completed for the Utah location. The average and median concentration for 115 accessions was 2.0% (DM basis), with a range of 0.6-4.0; the commercial control “Oberhaunstädter”, which is considered a high tannin cultivar, had an average concentration of 1.7.  Results thus far indicate that the germplasm collection contains material of interest for a BFT improvement program.