Solid Matrix Priming Hastens Canterbury Bells Seed Germination

Canterbury bells ( Campanula medium `Champion Blue') seeds were primed using calcined clay at 68 °F (20 °C) for 1, 3, or 5 days at water potentials (Ψ) of -25, -20, -18, or -16 bars (-2.5, -2.0, -1.8, or -1.6 MPa). Germination was fastest (3.0 to 3.1 days) after priming with a Ψ of -18 or -16 bars for 5 days. Seeds primed for 3 or 5 days with moisture present germinated faster than nonprimed seeds, but time to 50% germination (T 50 ) was longer when seeds were primed for 1 day regardless of Ψ compared to nonprimed seed. Germination uniformity decreased (time from 10% to 90% germination, T 10-90 , increased) as Ψ increased. Although a curvilinear relationship existed between T 10-90 and priming duration, T 10-90 did not differ between nonprimed seeds and seeds in any priming treatment except those primed for 3 days with 20% moisture (-16 bars). Priming did not affect total germination percentage (97%).