Effects of Moisture and Temperature on Germination of Idaho Fescue

Abstract

Germination response to varying temperatures and water stress levels during a 30-day incubation period was observed in 4 eastern Oregon collections of Festuca idahoensis Elmer. Seeds were selected from the following habitat types: Artemisia tridentata ssp. wyomingensis/Festuca idahoensis (ARTRV/FEID), Pinus ponderosa Dougl./Festuca idahoensis (PIPO/FEID). One stand of each habitat type was sampled, except for the ARTRV/FEID habitat type where seed was selected from both a high and low elevation plant community. The low elevation stand will be designated ARTRV"L"/FEID. Incubation temperature treatments were held constant (+/- 2 degrees C) and ranged in 5 degrees C increments from 5 degrees C to 35 degrees C. At 15, 20, and 25 degrees C, water stresses of 0.0 MPa, -0.6 MPa, and -0.9 MPa were depressed using polyethylene glycol 6000. Collectively, maximum total germination for all collections occurred at and above 10 degrees C and below 30 degrees C. Germination percentages for seeds from ARTRW/FEID, ARTRV/FEID and PIPO/FEID habitat types at 10 degrees C were 93.0, 97.0, 91.9, and 88.8%, respectively. Maximum germination rates for all collections occurred between 20-25 degrees C. As water stress decreased and temperature increased, both germination amount and rate for the 4 collections declined. Seeds of Idaho fescue collected from sagebrush habitat types maintained higher germination amounts and faster germination rates over wider temperature and moisture stress regime than did seeds selected from the PIPO/FEID site.