Optimization of seed priming treatments to increase low-temperature germination rate.

Abstract

Seeds of 4 range grass species were evaluated to determine the effects of priming-temperature, priming-water potential, and treatment-duration on subsequent germination response at 10 degrees C. Seeds of bluebunch wheatgrass [Pseudoroegneria spicata (Pursh) Love], thickspike wheatgrass [Elymus lanceolatus (Scribn. and J.G. Smith) Gould; syn. Agropyron dasystachyum (Hook.) Scribn.], sandberg bluegrass (Poa sandbergii Vasey.), and bottlebrush squirreltail [Sitanion hystrix (Nutt.) J.G. Smith] 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 determine optimal priming conditions among all treatment combinations that did not result in premature radicle emergence from the seed coat. Most rapid germination of treated seeds was obtained at priming temperatures considered optimal for germination of untreated seeds. Optimal priming conditions were found to be at water potentials equal to, or less negative than, the threshold water potential at which radicle emergence was prevented for untreated seeds. Germination response data for untreated seeds can be used to simplify the estimation of optimal temperature and water potential conditions for seed priming.