Submitted to: Journal of Range Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/1/1998
Publication Date: N/A
Interpretive Summary: Field performance of seeds is relatively difficult to predict given the natural variability in soil temperature and moisture at seeding depth. Previous attempts to predict potential field performance of rangeland grass seeds have involved large scale studies designed to simulate a wide variety of alternating day-night temperature regimes. This study was designed to determine whether germination response to variable temperatures could be predicted using a model constructed with only constant-temperature germination data. We found that for non-dormant seeds, in cold to moderately warm temperature conditions, it was possible to accurately predict cumulative germination response using data from relatively few constant-temperature germination data. This information can be used by the seed production and testing industry to predict potential germination success under a wide variety of potential field conditions. This could lead to new seed assessment strategies given the relatively low cost of constant vs variable-temperature germination testing.
Technical Abstract: The objective of many laboratory-germination experiments is to develop insight into the process of field establishment. It is relatively difficult, however, to infer potential field response from laboratory data given the enormous spatial and temporal variability in seedbed microclimate. Previous studies have attempted to survey large numbers of alternating day/night temperature regimes in order to estimate germination response to potential conditions of field microclimate. The objectives of this study were to estimate the errors associated with prediction of variable-temperature germination response from fewer, constant-temperature germination data. Non-dormant seeds of thickspike wheatgrass [Elymus lanceolatus (Scribn. and J.G. Smith) Gould], bluebunch wheatgrass [Pseudoroegneria spicata (Pursh) L¿ve], sandberg bluegrass (Poa sandbergii Vasey.) and bottlebrush squirreltail [Elymus elymoides (Raf.) Swezey] were germinated under constant, alternating-constant and sine-wave temperature patterns. Predicted and measured germination response generally coincided to within half a day for most temperature regimes and species subpopulations. Thermal response models can be parameterized from relatively few experimental data but provide predictive inferences relevant to a wide number of variable-temperature conditions.