Invasion in the Nation: How Does Temperature During Dormancy Influence Germination Rates of Humulus japonicus

Abstract

Humulus japonicus is currently in the Eastern United States, but is rapidly migrating West and heading straight for Montana. The effects of climate change have already been seen in Montana, and more changes are expected to occur in the future. These shifts could produce a climate that would allow H. japonicus to thrive on our open lands. H. japonicus is an annual invasive species that can out compete native species in riparian and floodplain habitats, altering ecosystem function. Previous studies have shown that H. japonicus seeds need some kind of cold stratification in order to break seed dormancy. For our study we aimed to answer the following question: Does the environmental temperature Humulus japonicus seeds are stored in prior to germination influence seed germination and growth? Groups of seeds were exposed to a designated range of different temperatures for 4 weeks and then placed in the greenhouse to evaluate germination. It was hypothesized that the seeds stored at cold (approx.4°C) temperature will germinate once placed in an ideal growing environment. The growth rates of the seeds that successfully germinated were recorded and evaluated from each temperature range. If H. japonicus does require cold stratification, we expect that colder seed treatments will result in greater and more rapid seed germination. The seeds that have the ability to grow after sitting in adverse temperature conditions indicate the invasive species, H. japonicus, have the ability to grow in the state of Montana if spread to the region.