Do Abrasion- or Temperature-Based Techniques More Effectively Relieve Physical Dormancy in Seeds of Cold Desert Perennials?

Seed dormancy can present a significant barrier to restoration outcomes in dryland systems Physical and combinational (physical + physiological) dormancy are prevalent among seeds of many heibaceous perennials used in restoiation of drylands throughout the western United States Although many techniques designed to alleviate these dormancy traits exist, then efficacy is species specific, may result in embryo damage, and may have limited large-scale application To identify the most effective means of dormancy alleviation with the potential to be used on an opeiational scale, we examined the effects of 16 tempeiatuie-based techniques (altering temperature and duration of wet heat, freezing and wet heal, and freeze-thaw cycles) and 6 abrasion-based techniques (altering pneumatic scarification length or using a single duration of manual scarification) on the enhancement of seed permeability among two physically dormant (western prairie clover [Dalea ornata {Douglas} Eaton & Wright] and Munro's globemallow [Sphaeralcea mum munroana {Douglas} Spach]) and two combinationally dormant species (basalt milkvetch [Astragalus filipes Torr. ex A Gray] and longspur lupine [Lupinus at arbustus {Douglas} ex Lindl.]). We first assessed seed imbibition following exposure to all temperature- and abrasion-based techniques to identify those most successful at promoting seed permeability and then evaluated the effectiveness of those techniques through a series of germination experiments For combinationally dormant species, we also tested whether exposure to GA(3) enhanced germination Abrasionbased techniques were more effective than temperatur e-based techniques at improving water uptake across all species. Pneumatic scarification significantly improved germination, but optimal treatment durations were species specific GA(3) did not enhance germination under the tested conditions. We conclude that pneumatic scrification is a fast, safe, and effective method for alleviating physical seed dormancy with a potential to be scaled up for operational use in restoration. (C) 2018 The Society for Range Management. Published by Elsevier Inc. All rights reserved.