GERMINATION AND SEEDLING EMERGENCE OF PRIMED TOMATO AND ASPARAGUS SEEDS UNDER ADVERSE CONDITIONS

Seeds of 'Ace 55' tomato (Lycopersicon esculentum Mill.) and 'Mary Washington' asparagus (Asparagus officinalis L.) were primed in -0.8 MPa (20C, 1 week, dark) polyethylene glycol 8000 (PEG), synthetic seawater (INO), or NaNO3. Primed seeds of both species had a higher percentage of germination than untreated seeds only at 10C in nonsaline (-0.05 MPa) medium, while in saline medium (-0.6 MPa) priming increased the percentage of germination of tomato seeds at 10 and 30C, and of primed asparagus seeds at 10 and 20C. Sodium nitrate was superior to PEG or INO for priming tomato seeds since it resulted in fewer days to 50% germination and higher final germination percentage in saline media at all temperatures. INO was a satisfactory alternative to PEG or NaNO3 for priming asparagus seeds since priming agent had little or no effect on germination. Seedling emergence from NaNO3-primed seeds of both species sown in a seedbed provided saline (-0.39 MPa) irrigation was faster than from untreated dry-sown seeds. In the saline seedbed, priming increased final emergence percentage (FEP) from asparagus seeds, provided they were not subsequently dried, but had no effect on the percentage emergence of tomato seeds. Fluid-drilling primed or germinated seeds of either species enhanced seedling establishment in the saline seedbed by reducing time to 50% emergence and/or increasing FEP relative to primed, dried-back or untreated seeds.