Submitted to: Society for Range Management Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: November 26, 2001
Publication Date: March 20, 2002
Citation: HARDEGREE, STUART P., JONES, THOMAS A., and VAN VACTOR, STEVEN S., Variability in Thermal Response of Primed and Non-primed Seeds of Squirreltail (Elymus elymoides (Raf.) Swezey and Elymus multisetus (J.G. Smith) M.E. Jones). Annals of Botany Company 2002, p. 311-319. Technical Abstract: Bottlebrush squirreltail [Elymus elymoides (Raf.) Swezey = Sitanion hystrix (Nutt.) J.G. Smith] has a broad geographic distribution and has been identified as a high priority species for restoration of degraded rangelands in the western United States. The objective of this study was to examine intraspecific variability in thermal response of both primed and nonprimed seeds of bottlebrush squirreltail in the context of field- variable temperature regimes. Seed priming treatments were selected to optimize germination rate in a low-temperature test environment. Primed and nonprimed seeds were evaluated in the laboratory for germination response under 12 constant-temperature treatments between 3 and 36øC. Thermal-time and base temperature were estimated by regression analysis of germination rate as a function of temperature in the sub-optimal temperature range. The thermal-germination model and 6-years of field- temperature data were used to simulate potential germination response under alternative field planting scenarios. Seed priming reduced total germination percentage of some seedlots, especially at higher germination temperatures. Seed priming increased germination rate (as measured by days to 50% germination) by 0.5 to 8.5 days at 6øC with a mean germination advancement of 6.3 ñ 0.8 days. Maximum germination advancement in the model simulations was 2-10 days for planting dates between March 1 and May 15.Model simulations can be used to expand germination analysis beyond simple treatment comparisons, to include a probabilistic description of potential germination response under historical or potential future conditions of seedbed microclimate.