The biomass and nutritive potential of Vallisneria americana Michx in navigation pool 9 of the upper Mississippi river

Abstract

Vallisneria americana Michx (wild celery) was studied to determine the biomass and nutritive potential of all morphological structures. A 2.6-ha stand of uniform V. americana was sampled during the summer and autumn of 1980, and the spring and summer of 1981 in the southern portion of Navigation Pool 9 of the Upper Mississippi River. The maximum production rate of 3.2 g m −2 day −1 was coincident with rapid rosette production and flowering, and occurred mid- to late-July 1980. The maximum biomass of 217.3 g dry wt. m −2 was on 1 September 1980, when fruit development was also at a maximum. Leaves composed 60–70% of the summer biomass; winter buds constituted all of the winter biomass. Winter buds and fruits had the greatest nutritive potentials. Both organs contained relatively high dry matter concentrations and were low in ash (less than 10%) and fiber content. The potentially-digestible ash-free non-cell-wall fraction (NCF) was composed of an average of 75.7 and 82.2% of the dry weight of fruits and winter buds, respectively. In contrast, the nutritive potential of leaves, rootstocks, peduncles and stolons was reduced because of high moisture (less than 8% dry matter), ash and fiber concentrations. Staminate inflorescences and pistillate flowers were high in crude protein (averaged 21.8% and 16.1% of the dry-weight, respectively) and ash-free non-cell-wall fractions, but they accounted for only 2.7% of the plant biomass. The maximum calorific content of V. americana was approximately 3200 kJ m −2 at peak biomass on 1 September 1980.