Wild rice (Zizania Palustris) seed biology: germination under a changing climate

Manoomin/psiɳ (Zizania palustris) is the native wild rice that has grown in shallow freshwaters in the Great Lakes Region of the United States for thousands of years. Tribal communities that consume wild rice have had a symbiotic relationship with the plant for generations. Unfortunately, numerous disturbances now threaten manoomin/psiɳ populations and there have been decreases in its abundance. Impacts to manoomin/psiɳ include anthropogenic impacts like development, pollution, and climate change, which alters plant phenology and plant community dynamics. Concerns regarding climate change impacts on wild rice guided my research on how changes in winter conditions will impact manoomin/psiɳ germination and how seed traits influence germination and early seedling growth. Specifically, I investigated how differences in winter duration, temperature, and water levels influence overall seed germination and germination rates (time to germination). In addition, I sought to determine how seed maturity, seed accessories, and seed mass affect seed germination, which has potential implications for seed-based restoration efforts. Seeds for experiments were collected from two natural stands of wild rice and climate treatments were applied in controlled-environment growth chambers. Seeds were subjected to longer (8 months) or shorter (4 months) and colder (-4C) or warmer (4C) overwintering conditions. There were significant effects of these treatments on germination rates but not the overall proportion of seeds that germinated. Shorter winter durations resulted in a faster germination rate (p = 0.001), and below-freezing temperatures decreased germination rate (p < 0.0001). Seeds subjected to dry overwintering conditions, mimicking “fringe rice” not covered by water and ice, did not significantly differ in overall germination (p = 0.21). Seed measurements were taken to analyze seed traits' influence on germination and early seedling growth. Seeds were diverse in size and shape, with modest but highly significant positive correlations between seed length and width (r = 0.26; p < 0.0001). Removing seed hulls yielded higher initial germination (p < 0.001). Seeds that appeared more mature based on color were more likely to germinate and germinated more quickly (p = 0.047). Seed mass was strongly positively correlated with seedling mass (r = 0.83; p < 0.0001). More biomass was allocated to shoot growth than root growth, which were also positively correlated (r = 0.78; p < 0.0001). Understanding manoomin/psiɳ health is an ongoing, interdisciplinary effort that depends on multiple ways of knowing. The steady decline of manoomin/psiɳ in recent years shows that protecting manoomin/psiɳ will require efforts related to climate mitigation, land conservation, and reseeding/restoration.

Author dc:creator

• Torres, Sirena

Language dc:language.iso

en

Handle dc:identifier.uri

https://hdl.handle.net/11299/278015

OAI identifier oai:identifier

oai:conservancy.umn.edu:11299/278015