SEED-GERMINATION RESPONSE OF 4 SOUTHWESTERN RANGE GRASSES TO EQUILIBRATION AT SUBGERMINATION MATRIC-POTENTIALS

Seed priming at subgermination water potential has been shown to enhance the germination response of a wide number of plant species. Optimal priming conditions for germination enhancement are usually found to be at the least negative water potential that prevents radicle emergence. Equilibration of seeds at more negative water potentials may have detrimental effects on germination relative to control treatments. Seeds of Bouteloua curtipendula (Michx.) Torr., Cenchrus ciliaris L., Eragrostis lehmanniana Nees, and Panicum coloratum L. were equilibrated over the matric potential range of -1.6 to -17.5 MPa and germinated over the matric potential range of 0 to -1.6 MPa. Matric-priming at -1.6 MPa frequently increased germination percentage and rate at reduced water potential. Matric-priming at water potentials more negative than -1.6 MPa had a less positive and sometimes detrimental effect on germination relative to control treatments. Germination response of primed seeds showed a tendency toward, but not necessarily achievement of, control levels at the most negative priming-water potentials.