Investigating seed dormancy and germination of important Wyoming forbs

Abstract

Native forbs are an essential component of healthy sagebrush steppe plant communities; however, restoration of native forbs throughout Wyoming is limited. Many forbs native to Wyoming have unknown seed dormancy and germination requirements contributing to the low availability of native seed for use in restoration. This study aims to develop a better understanding of seed dormancy traits and germination requirements of 8 native forb species as a critical step toward getting more native species into seed production to improve restoration success. We first evaluated the water permeability of seeds to test for the presence of physical dormancy. We then conducted baseline germination testing across a range of ecologically relevant temperatures to determine if physiological dormancy was present. For species exhibiting evidence of dormancy, we tested the effects of manual scarification, 4 different cold stratification durations, and exposure to the germination stimulant gibberellic acid on seed germination. Physical dormancy was relieved in 2 species with manual scarification alone, and physiological dormancy was relieved in 3 species with 2 to 4 mo of cold stratification. Among the tested species, exposure to gibberellic acid alone was not sufficient to break dormancy and promote germination ≥75% but did significantly increase germination for 2 species over the control. While further testing is needed to fully characterize seed dormancy, optimize germination, and inform operational seed treatments for these species, our findings highlight the importance of seed research as a key step toward improving seed availability and effective use of important forbs native to Wyoming in restoration efforts.