A COMPARISON OF PRIMING AGENTS FOR TOMATO AND ASPARAGUS SEEDS

Tomato (Lycopersicon esculentum Mill.) and asparagus (Asparagus officinalis L.) seeds were primed for 1 week in -0.8 MPa (20C, dark) polyethylene glycol 8000 (PEG), synthetic seawater (INO), or combinations of Ca+2, K+, or Na+ with Cl-, NO3-, H2PO4-, or SO4(-2)) and then were placed in 0.5-fold Hoagland solution at 20C for germination. Priming did not affect percentage germination of tomato seeds; but asparagus germination increased from 85% in untreated seeds to 90% due to priming. All priming treatments reduced the time to 50% germination (G50) of both species but reduced the time between 10% and 90% germination (G10-90) of only tomato seeds. Salt solutions gave lower G50 values than PEG for tomato seeds but did not provide this advantage for asparagus seeds. The G50 and G10-90 of tomato seeds were lower after priming with nitrate salts than with other salts, but the reductions were greatest with sodium nitrate. The G50 of asparagus seeds was lowered with nitrate salts, but the G10-90 was unaffected.