Germination rate and emergence success in bluebunch wheatgrass.

Abstract

Development of plant materials adapted to the demands of a harsh environment and conditions created by standard planting practices has resulted in improved seedling establishment for some species. Bluebunch wheatgrass (Pseudoroegneria spicata [Pursh] Love) is an important native bunchgrass often planted in the Intermountain and Pacific Northwest regions. Though cultivars have been developed, this species continues to have a reputation for weak seedlings. Forty-seven accessions of bluebunch wheatgrass collected from naturally occurring populations in 9 geographic regions and the cultivar 'Goldar' were evaluated for germination rate, seedling emergence and growth, and seed weight. Significant differences in seed weight and germination rate at optimum (15/25 degrees C) and cold (1 degree C) temperatures were observed. Seedling emergence from a 4-cm depth ranged from 5 to 66%. Mean dry shoot weight 28 days after planting varied among accessions by a factor of 6. Simple correlations between seed weight and percentage emergence (r = 0.62) and seed weight and mean shoot weight (r = 0.63) indicate seed weight could be used as a preliminary screening test for these traits. Seed weight was not useful in predicting germination rate. Results suggest establishment success may be improved through careful selection for traits associated with seedling vigor.