To study the effects of the hydrological regimes of lakes and rivers on seed size of
wild rice (Zizania palustris), four lakes and four rivers were sampled to measure and
model the factors affecting seed size. Based on casual observation by harvesters and
biologists it has been hypothesized that seeds produced in riverine habitats are smaller
than those produced in lacustrine habitats. We found mean seed mass in lake populations
was 15.4 mg (41%) larger than in river populations. When seed mass was partitioned
between water body type, regional population pair, and individual population, water body
type accounted for 71.3% of the variance. Data collected on seed mass, panicle density,
seed scars, root mass, sediment characteristics, and water depths were used to create a
statistical model to quantify the effects of each factor on seed size. The two most
important environmental factors contributing to seed size were sediment bulk density and
water depth at seed collection. Important biological components were seed scar density, proportion of filled seed, and root dry mass.
University of Minnesota M.S. thesis. October 2010. Major: Conservation biology. Advisors: Raymond M. Newman, David D. Biesboer. 1 computer file (PDF); vi, 38 pages, appendices 1-3.
Eule-Nashoba, Amber Rae.
Seed size in lacustrine and riverine populations of wild rice (Zizania palustris).
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