INFLUENCE OF STORAGE, TEMPERATURE, AND LIGHT ON GERMINATION OF JAPANESE BROME SEED

Japanese brome (Bromus japonicus Thunb.), an alien annual grass, is an important component of some northern mixed-prairie communities. Under standing the relationship between environment and population dynamics for this species is critical for efficient management of infested rang es. Our objective was to determine the germination pattern of seed har vested in the Great Plains with varying collection dates, storage cond itions, incubation temperatures, and light regimes. Seeds were collect ed from inflorescences (nondisseminated seed) during July in Oklahoma and Montans and during November and December in Montana. July collecti ons were stored in paper sacks in a laboratory, and November and Decem ber collections were divided into thirds and stored in an unheated war ehouse, oven-dried at 46-degrees-C, or frozen at - 18-degrees-C. Seeds were germinated in 2 regimes, where temperatures alternated every 12 hours and light was provided during the 12 hours of high temperature. One regime provided 10 days of prechilling (0 and 10-degrees-C) follow ed by 18 days of a warm temperature (8 and 23-degrees-C) (chilling). A nother regime consisted of 28 days of the warm temperature (warm). Sam ples of seeds were also imbibed in the warm regime with 12-hour or int ermittent periods of light. July collections germinated rapidly to > 9 0% regardless of temperature. November and December collections stored in the warehouse germinated > 70% in the warm regime, but germination was reduced to < 20% with chilling, suggesting secondary dormancy was induced by imbibition at 0-degrees-C. Oven drying was the only treatm ent that consistently reduced maximum germination. Darkness enhanced 7 -day germination, but light improved 28-day germination, and more rece ntly collected seeds were more sensitive to light than older ones. The se and earlier findings from Kentucky suggest Japanese brome seeds gro wn in different locations respond similarly to changing environmental conditions.