Germination of Basin Wildrye and Tall Wheatgrass in Relation to Osmotic and Matric Potential 1

Tall wheatgrass [ Agropyron elongatum (Host) Beauv. ‘Jose’] and basin wildrye ( Elymus cinereus Scribn. and Merr. ‘Magnar’) may have great potential for increasing the forage production of saline and arid rangelands. To determine the potential of these species to germinate and emerge in saline, arid seedbeds germination responses were studied in the laboratory in relation to decreasing medium osmotic and matric potentials, seed water contents, and seed water potentials. Tall wheatgrass had higher total germination, a higher germination rate and greater radicle growth than basin wildrye in solutions of polyethylene glycol 6000 (PEG), NaCl, Na 2 SO 4 , and CaCl 2 . Ion toxicity was evidenced by lower germination rates and radicle growth of both species in the salts than in PEG. Tall wheatgrass seeds were more tolerant of Na and chloride than of Ca or sulfate ions. Tall wheatgrass required less incubation days to emerge and emerged at lower soil matric potentials than basin wildrye. Both species had lower emergence in soil at reduced matric potentials than in PEG and salt solutions of equivalent osmotic potentials where seed‐soil contact and hydraulic conductivity were not limiting factors. Tall wheatgrass germinated at lower seed water contents and seed water potentials than basin wildrye. Although Jose tall wheatgrass is more likely to germinate and emerge in saline, arid seedbeds than Magnar basin wildrye, Magnar has higher germination and germinates at lower osmotic potentials than other collections of basin wildrye previously tested.