Seed isolates of Alternaria and Aspergillus fungi increase germination of Astragalus utahensis

Abstract

Astragalus utahensis (Torr.) Torr. & A. Gray (Fabaceae) (Utah milkvetch) is native to the arid Great Basin and has desirable attributes that make it a good candidate for restoration in arid, noncompetitive situations. Seed dormancy is a significant barrier to consistent establishment for this species. Species of Alternaria and Aspergillus fungi have potential to enhance germination of A. utahensis seed; therefore, we conducted trials to investigate Alternaria and Aspergillus effects on germination and emergence under controlled in vitro conditions or in soil in a growth chamber, in a greenhouse, and in the field. Seed was either acid scarified or left untreated and then inoculated with spores from Alternaria and Aspergillus. Under in vitro and greenhouse conditions, rates of germination or emergence increased significantly for seed inoculated with the 2 fungi. Inoculated seed in field experiments planted at Fountain Green and Nephi, Utah, had significantly higher emergence rates than the non-scarified/non-inoculated control, and Aspergillus-inoculated seed outperformed seed treated with Alternaria. Inoculation of seed planted at Spanish Fork did not provide an advantage over acid scarification, but all treatments showed greater emergence than the non-scarified/non-inoculated control. This study demonstrates that inoculating A. utahensis seed with Alternaria or Aspergillus prior to planting has a positive impact on rates of emergence in a field setting.