The Influence of dormancy break requirements on germination and viability responses to winter submergence in acorns of three bottomland red oak (Sect Lobatae) species
The objective of this study was to examine the relationship of dormancy break requirements to winter submergence effects on germination and viability in cherrybark, willow, and Nuttall oak acorns. Acorns were submerged in a greentree reservoir and received 0, 21, 42, 63, or 84 days of winter submergence, followed by 8 weeks of incubation in four alternating temperature regimes (15/6°, 20/10°, 25/15°, and 30/20° C). Submergence substituted for cold stratification requirements of cherrybark oak acorns, and dormancy break was achieved with 63 days of submergence. Although submergence exerted a positive effect on germination in Nuttall and willow oak acorns, dormancy break was not achieved in acorns of either species. Germination percentages were highest in the 30/20 °C incubation temperature — cherrybark oak acorns (59% - 83%), followed Nuttall oak (33% - 62%) and willow oak (14% - 52%). Among treatment combinations, all willow oak nongerminants were viable. Viability loss in cherrybark and Nuttall oak acorns was greatest in the 63 and 84 day treatments. The dynamics of acorn germination in response to winter hydrologic regime is, in large part, directed by submergence duration that may, or may not, satisfy dormancy break requirements in acorns of these red oak species.