Seed germination of selected crop and graminoid species in response to treatment with sodium chloride and oil-field brine solutions

Abstract

Oil and gas development is often associated with the production of produced water or “brine”, which is a solution of dissolved salts (NaCl ≈ 90%) exhibiting electrical conductivity (EC) upwards of 200 dS m−1. Accidental releases of brine to soils inhibit seed germination through osmotic and ionic stressors. The final germination (FG; %) of four crop species, Hordeum vulgare L. (barley), Helianthus annuus L. (sunflower), Carthamus tinctorius L. (safflower), Beta vulgaris L. (sugar beet); and four graminoid species, Pascopyrum smithii (Rydb.) Barkworth & D.R. Dewey (western wheatgrass), Elymus hoffmannii K.B. Jensen & Asay (AC Saltlander), Leymus triticoides (Buckley) Pilg. (beardless wildrye), and Elymus trachycaulus (Link) Gould ex Shinners (slender wheatgrass), were determined using sodium chloride (NaCl) and brine solutions prepared at EC levels of 0, 4, 8, 16, 24, and 32 dS m−1. No differences (p > 0.05) in FG were found between NaCl and brine solutions across graminoid species or the crop species barley, sunflower, and sugar beet. AC Saltlander had the highest FG (81.9%) at the maximum EC level (32 dS m−1), compared with 47.2% and 0.8% for western wheatgrass and beardless wildrye, respectively. Within crop species, safflower exhibited the highest germination (10%–30%) across both solutions at 32 dS m−1. Barley (0%–2.9%), sugar beet (4.9%–7.7%), and sunflower (0%–1.4%) exhibited low germination at 32 dS m−1. The implications of this experiment are that previously established NaCl tolerance indices may be used to accurately determine the FG of plant species in brine-contaminated soils and that AC Saltlander, as well as western wheatgrass, have the highest FG at 32 dS m−1, indicating these species may have the greatest potential for successfully revegetating brine-contaminated soils.