For thousands of years, wild rice has been an important part of the ecosystem. Evidence of wild rice has been gathered from nearly 9,000 years ago. According to archeological record, wild rice was obtained as a food source about 2,000 years ago. Since then, many mammals (including human beings) have relied on wild rice as a form of nourishment (Drewes, 2005).
Zizania palustris, or Northern Wild Rice, is one form of wild rice still present today. Specifically, Z. palustris is native to northern central United States and part of Canada. The bases of these annual plants are most commonly found growing no less then 2ft (~60cm) under water near the edges of shallow lakes and slow moving streams. Reaching up to 10 ft (~3m), Z. palustris is distinctive because of its large flowery head and well-defined male and female parts (Iowa State, 2004). (However, it is important to note that the strain of Northern Wild Rice used in this study is a cultivated form, not native, as this may change some implications of the study as a whole.)
Zizania palustris is typically categorized as a hydrophyte; a plant that grows in very wet environments either wholly or partly submerged in water (Graham et al 1994) . Because a significant portion of the plant is submerged in water, the leaves have adapted to survive in this unique environment. The thickness of the cuticle is related to the plants degree of submersion in water. Because Z. palustris has some emerging leaves, the cuticles are well developed (Graham et al., 1994).
According to Drewes (2004), wild rice species have been on the decline in the past fifty years. For example, according to the University of Wisconsin Herbarium, samples of wild rice have been taken from the Lake Wingra shore in Madison, Wisconsin, as early as 1895 (L.S. Cheney). However, the last spotted Zizania palustris specimen in the Dane County area occurred in 1959 (T.E. Melchert). Drewes attributes this decline to changing land use, increased settlement and changes in the hydrological regime. Less then twenty years before the last sighting of the northern wild rice species, a change occurred in the Lake Wingra Watershed. Between 1959 and 1960, the first recorded use of salt as a road de-icer occurred. In ongoing studies by the City of Madison Public Health Department and Dr. James Lorman at Edgewood College, the chloride content of Lake Wingra has increased dramatically almost every year since the introduction of road salt as a de-icer. At near toxic levels, road salt has undoubtedly been harming the Lake and its habitants. This study attempts to examine the effects of extreme road salt usage on the decline in wild rice.
According to a special report on Highway Deicing (NRC, 1991), regulatory standards for surface waters are about 395 mg/L of chloride. Groundwater standards were concluded to be around 250 mg/L of chloride. In recent years, areas around Lake Wingra have been sampled for chloride levels. In February 2005, Edgewood College’s retention pond was tested for chloride concentration. Researchers found an average of 4,560 mg/L of chloride.
In this study the germination rate of wild rice seeds in a number of different prepared solutions with both high and low salt concentrations was determined. I hypothesized that, with a higher concentration of NaCl in the water, the Z. palustris seeds will be less likely to germinate, and therefore have a lower success rate for germination.