Hoary Cress (Cardaria draba) Root Extract Reduces Germination and Root Growth of Five Plant Species1

The allelopathic potential of hoary cress was evaluated by exposing the seeds and the germinated seeds of winter wheat, alfalfa, crested wheatgrass, bluebunch wheatgrass, and hoary cress to a water extract of dried, hoary cress roots under controlled conditions in an environmental chamber. Germination for all species was reduced in the hoary cress root extract when compared with distilled water, with winter wheat and hoary cress being more tolerant than the other species. Root length of all species was reduced by the extract when compared with distilled water. These data show the presence of phytotoxic chemical(s) that may inhibit germination and initial seedling growth in natural environments. Three glucosinolate compounds were identified in hoary cress root extracts.Nomenclature: Glucosinolate; alfalfa, Medicago sativa L. ‘Latac’; bluebunch wheatgrass, Pseudoroegneria spicata (Pursh) A. Love; crested wheatgrass, Agropyron cristatum (L.) Gaertn.; hoary cress, Cardaria draba (L.) Desv., #3 CARDR; wheat, Triticum aestivum L. ‘Hill 81’.Additional index words: Allelopathy, Brassicaceae, glucosinolates.