OPTIMIZATION OF SEED PRIMING TREATMENTS TO INCREASE LOW-TEMPERATURE GERMINATION RATE

Seeds of 4 range grass species were evaluated to determine the effects of priming-temperature, priming-water potential, and treatment-durati on on subsequent germination response at 10 degrees C. Seeds of bluebu nch wheatgrass [Pseudoroegneria spicata (Pursh) Love], thickspike whea tgrass [Elymus lanceolatus (Scribn, and J.G. Smith) Gould; syn. Agropy ron dasystachyum (Hook.) Scribn.], sandberg bluegrass (Pea sandbergii Vasey.), and bottlebrush squirreltail [Sitanion hystrix (Nutt.) J.G. S mith] were primed over the temperature range of 5 to 35 degrees C and the water potential range of 0 to -2.5 MPa for up to 10 days to determ ine optimal priming conditions among all treatment combinations that d id not result in premature radicle emergence from the seed coat. Most rapid germination of treated seeds was obtained at priming temperature s considered optimal for germination of untreated seeds. Optimal primi ng conditions were found to be at water potentials equal to, or less n egative than, the threshold water potential at which radicle emergence was prevented for untreated seeds. Germination response data for untr eated seeds can be used to simplify the estimation of optimal temperat ure and water potential conditions for seed priming.