WHAT REGULATES SEED AND BULB DORMANCY IN THREE WILD ALLIUM SPP.

Phillips, N.¹, Drost, D.T.¹, Varga, W.¹, Kjelgren, R.¹, Schultz, L.², Meyer, S.E.³, and Larson, S.⁴

¹ Plants, Soils, and Biometeorology Department, Utah State University. Logan, UT 84322-4820, ²Forest, Range, and Wildlife Science Department, Utah State University. Logan, UT 84322-5230, ³USDA Forest Service - RMRS - Shrub Sciences Laboratory. Provo, UT 84606, ⁴USDA-Agricultural Research Service. Logan, Utah. 84322

In the Intermountain West, seed and bulb dormancy mechanisms in geophytes must be understood before efficient propagation methods can be developed. These dormancy characteristics regulate germination, growth, and reproductive development. We are studying three geophytic species native to Utah; Allium acuminatum, A. brandegei, and A. passeyi. Three wild populations of each species were chosen along elevation gradients to represent within species habitat differences. By assessing life history and growth characteristics, demographics, climatic factors, and genetic variability in each of these populations, and comparing this field study data with laboratory germination and growth studies, we can assess the dependence of germination and growth requirements on population. These relationships will enable us to develop a predictive propagation model for native geophytes. Preliminary germination results show physiological dormancy in the seeds of each of the three species. Cold moist stratification provides the optimal environmental conditions to initiate embryo growth. Allium acuminatum and A. passeyi germination percentages were highest when stratified at 3C for 12-20 weeks. Stratification temperature did not affect A. brandegei germination, but germination percentages increased with increasing stratification duration. Populations of each species were monitored beginning in spring 2004. Within-species variation of population demographics was evident in all species, and appears to be correlated with elevation. Leaf senescence responded to elevation differences, with senescence occurring earlier in the season at lower elevations, suggesting that photoperiod has no effect on induction of bulb dormancy, while temperature might play a primary role in bulb dormancy timing. Further germination and growth experiments will assess population effects on seed and bulb dormancy characteristics during 2005 - 2006.

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