Media selection and seed coating influence germination of turfgrasses under salinity.
Germination of five turfgrass species ['Barrister' kentucky bluegrass (Poa pratensis L.), 'Barvado' tall fescue (Festuca arundinacea Schreb.), 'Premier II' perennial ryegrass (Lolium perenne L.), 'Bargusto' bermudagrass (Cynodon dactylon L. Pers.), and 'Sea Spray' seashore paspalum (Paspalum vaginatum O. Swartz)] from coated (ZEBA® cornstarch coating; Absorbent Technologies Inc., Beaverton, OR) and uncoated seeds was evaluated on both filter paper and agar. Final germination percentage (FGP) and germination rate (GR) were determined at salinity levels of 0.6 (tap water, control), 2.2 (saline groundwater from a local shallow aquifer), and 7.0, 12.5, and 22.5 dS.m-1 [sodium chloride and calcium chloride (1:1, w:w) dissolved in tap water]. Final germination percentage for kentucky bluegrass, perennial ryegrass, and tall fescue was greater in agar at all salinity levels but was unaffected by the medium at any of the salinities except for 7 dS.m-1 for bermudagrass and seashore paspalum. Coated seashore paspalum and coated perennial ryegrass seed exhibited greater germination than uncoated seed at four of the five salinity levels. Seed coating had no effect on FGP of bermudagrass at any salinity level and coated kentucky bluegrass seed showed reduced germination at 0.6 and 7.0 dS.m-1. Final germination percentage for seashore paspalum improved from 22% to 54% at 12.5 dS.m-1 and from 8% to 20% at 22.5 dS.m-1 when coated seed was used instead of uncoated seed. Germination rates were unaffected by salinity levels ranging from 0.6 to 12.5 dS.m-1 and were higher on agar (10%/day) than on paper (8%/day). Our study suggests that the choice of medium can influence the outcome of germination tests and that results can also vary depending on the salinity level tested and whether the seed are coated.