POLYETHYLENE-GLYCOL SOLUTION CONTACT EFFECTS ON SEED-GERMINATION

While polyethylene glycol (PEG) solutions have been used to control water potential in numerous seed germination investigations, there is concern that PEG solution-seed contact may reduce seed germination. The PEG solution-seed contact effect on seed germination was evaluated on four grass species: sideoats grama [Bouteluoa curtipendula (Michaux) Torreyl, buffelgrass [Cenchrus ciliaris L.], Lehmann lovegrass [Eragrostis lehmanniana Nees], and kleingrass [Panicum coloratum L.]. A water potential control system for seed germination was developed that controlled PEG (8000 mol. wt.) solution-seed contact. Seeds were germinated on filter paper and cellulose membrane over the water potential range of 0.0 to -1.62 MPa. Buffelgrass and Lehmann lovegrass 21-d germination and germination rate index (GRI) were not affected by PEG solution-seed contact. Sideoats grama and kleingrass showed reduced germination and GRI without PEG solution contact on the cellulose membrane. The reduction was attributed to the hydraulic conductivity at the seed-water-membrane contact point which was influenced by PEG solution water potential and seed size and shape. Therefore, it was concluded PEG solution-seed contact does not reduce seed germination.