Testing Seed Dormancy of Commercially Available Native Forb Species in the Northern Great Plains

Abstract

The demand for native seed is increasing nationally as more emphasis is being put on ecological restoration efforts. However, many seed-based restoration efforts are ultimately not successful. These failures are partially attributed to a lack of knowledge on species-specific germination and dormancy traits. A better understanding of these traits could alter restoration practices and result in a higher seeding effectiveness and greater plant establishment success. We tested nine forbs native to the Northern Great Plains, all of which have troubled restoration practitioners in the region. Our goal was to evaluate dormancy through overall germination and germination timing. Common dormancy-breaking treatments, including scarification, nitrate addition, smoke, and temperature manipulation, were performed to induce germination among the species. We chose to test commercially produced seeds (i.e., farmed), as the demand for native seed is driving practitioners and agencies to rely more on commercial production than wild harvest. Only three study species (Erysimum asperum, Gaillardia aristata and Ipomopsis aggregata) expressed dormancy. This was surprising because many public resources and studies on related species suggested dormancy is common with most of our study species. The lack of dormancy could be caused by many factors including more favorable growing conditions experienced during commercial production, and commercial handling and processing of harvested seed, among others. Continued research should focus on whether reduced dormancy is a pattern across restoration efforts using commercially produced seeds and, if so, how altered dormancy status may benefit or hinder our national efforts to reestablish sustainable grasslands.