Submitted to: Journal of Range Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 20, 1995
Publication Date: N/A
Interpretive Summary: Native perennial bunchgrasses in the Great Basin region of the western United States are being replaced over large areas by cheatgrass, a non-native annual grass. Cheatgrass establishes quickly after wildfire, outcompetes native vegetation, and increases fire frequency which can lead to widespread dominance of this undesirable weed. Affected areas include grazing land for livestock and wildlife, habitat of endangered and threatened species, riparian zones and wilderness. One mechanism that contributes to the competitive success of cheatgrass is its ability to germinate rapidly at low temperatures in the spring and fall. In this experiment, native grass seeds were treated so that they would germinate more rapidly at low temperature. A wide range of seed treatment conditions were evaluated to develop technology to optimize seed treatments for maximum enhancement of germination rate. The optimization procedures developed in this study resulted in a significant improvement in seed germinability for four native grass species. Three of the species were induced to germinate as quickly as cheatgrass in a low temperature test environment. This study is a significant step in developing larger scale seed treatment applications for rangeland seeding by public and private land management organizations.
Technical Abstract: Cheatgrass (Bromus tectorum L) has become the dominant species over large areas of rangeland in the Great Basin region of the western United States. Rapid germination at low temperature contributes to the competitive ability of cheatgrass. The objective of this experiment was to develop technology to optimize seed-priming treatments for enhancing low-temperature germination rate of native grasses. Seeds of bluebunch wheatgrass [Pseudoroegneria spicata (Pursh) L¿ve], 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 øC 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 extension. Most rapid germination of treated seeds was obtained at priming temperatures considered optimal for seed germination of untreated seeds. Optimal priming water potentials for all species except sandberg bluegrass were found to be in the intermediate water potential range that would normally result in radicle extension if treatment duration was extended.