Submitted to: Journal of Range Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 1, 1996
Publication Date: N/A
Interpretive Summary: Rangeland grass seeds are exposed to wetting and drying from precipitation. Once the seed is wet the germination process starts. There is a point in the germination process where it can stop from being dried and resume again when wet. Once this point is passed in the germination process and the seed is dried it will die. Knowledge on the ability of germinating seeds to withstand wetting and drying can be used to determine their potential for successful regeneration under the present and future climatic regimes. Sideoats grama, buffelgrass, lehmann lovegrass, and kleingrass seeds were evaluated for effects of short term wetting and drying sequences on subsequent 14 day germination response. One day of wet followed by drying was enough to advance the germination process to a point where the amount of germination was significantly reduced when compared to no drying. More than 48% of the viable seeds were still able to survive the one day wet and ddrying. Longer wet periods followed by drying severally reduced germination. This information will be useful to scientist in understanding why grasses establish in certain areas and to land managers in selecting the best grass species for revegetation based on the amount and frequency of precipitation.
Technical Abstract: Precipitation patterns in the arid southwest can be highly variable for seedling establishment during the summer monsoon season. The ability of germinating seeds to withstand temporary periods of dehydration may determine their potential for successful regeneration under present and future climatic regimes. Effects of short term hydration and dehydration sequences on seed germination were studied for Sideoats grama [Bouteloua curtipendula (Michaux) Torrey], buffelgrass [Cenchrus ciliaris L.], lehmann lovegrass [Eragrostis lehmanniana Nees], and kleingrass [Panicum coloratum L.]. Seeds were initially imbibed at -0.2 MPa for 1 to 4 days, then either air dried or partially dehydrated at -3.0 MPa for 1 to 4 days before being returned to the initial imbibition solution for a total 14-day incubation period. One day of imbibition was enough to advance the germination to a stage that resulted in significant reductions from subsequent dehydration. The length of the dehydration periods produced significant differences in 14-day germination for lehmann lovegrass and kleingrass. Dehydration both significantly increased and decreased germination rates. More than 48% of the viable seeds survived dehydration, after only 1 day of imbibition. Most seeds were damaged by dehydration after longer periods of imbibition.