Priming with Salt Solutions Improves Germination of Pansy Seed at High Temperatures
Priming regimes were evaluated on pansy seeds (Viola ×wittrockiana Gam. `Crystal Bowl Sky Blue') in high-temperature germination tests. Priming regimes evaluated included CaCl2, MgCl2, K2HPO4, Na2HPO4, NaCl, KCl, KNO3, Na2SO4, and polyethylene glycol 15,000 (PEG15,000) at –1.0 and –2.0 MPa, for 3, 6, or 9 d at 23 °C. Primed and nonprimed control seeds were then germinated at 25, 30, or 35 °C. Total percent germination of nonprimed control seeds was significantly less at 35 °C than at 25 °C. Seeds primed with CaCl2 at –1.0 MPa for 3 d at 23 °C had significantly higher germination at 35 °C than all other priming regimes tested, including aerated PEG8000 at –1.0 MPa for 7 d at 15 °C. Seed respiration, measured by O2 uptake, during germination of seeds primed with CaCl2 was higher than for control seeds or those primed with PEG8000. Priming pansy seed with CaCl2 at –1.0 MPa for 3 d at 23 °C was effective in increasing seedling emergence and for reducing the time of emergence in summer greenhouse studies.