Natural Growing Conditions Related to the Size and Nutritional Contents of Wild Rice Seeds

Abstract

Wild rice is a valuable food and cultural resource worth protecting from environmental degradation. Existing literature describes complex relationships between ecological indicators of wild rice health and the growth environment of wild rice, including sediment carbon/iron content, water levels, water clarity, invasive species, and surface water sulfate. While much is known about how growing conditions influence wild rice survival and reproduction, little is known about how growing conditions affect the nutritional content of wild rice seeds. The nutritional characteristics of wild rice seeds are a critical factor for human and wildlife consumption as well as sustaining healthy wild rice populations. The purpose of this study is to examine relationships between the size and nutritional composition of wild rice seeds and wild rice growing environments. Seeds, sediment, and surface water were collected at 43 sites spanning a range of lake and river environments, surface water sulfate concentrations (0.1 to 400 mg/L), and sediment carbon contents (1 to 30%). Results indicate that seed mass is highly variable (0.013 to 0.062), and that seed mass is influenced primarily by geographic location and waterbody type (lake or river). Several seed nutritional components are positively (K, Mg, Ca, Mn, P) or negatively (starch, Na, and Si) correlated with seed mass which could be caused by locations of elements within seeds. Few seed element concentrations other than calcium covary with either porewater or sediment concentrations. These identified relationships linking some seed nutritional characteristics to seed mass may allow wild rice harvesters to focus harvesting efforts based on desired seed characteristics.