| dc.description.abstract | Wild rice, grown in plastic buckets suspended from specially
designed rafts, was subjected to increases in water depth during
the submerged-leaf, first floating-leaf, second floating-leaf,
and the first aerial-leaf stages. The depth was increased from
the initial depth of 45cm by either 0cm (control), 15cm, 30cm,
or 50cm. With the exception.of the 15cm treatment, increases in
water depth resulted in decreases in the vegetative
characteristics of plant height, total and component (root, stem,
leaf) dry weights, and the number of tillers on each plant. As
water depth increased similar reductions occurred in the
reproductive characteristics of the number of inflorescences per
plant, the number of pedicels per plant, and the dry weights of
the inflorescences. The 15cm treatment had higher production
values than the control, possibly because the lower light levels
at the greater depth were closer to optimum for the particular
seed source used. The final biomass did not seem to be
influenced by the phenological stages when these depth increases
occurred.
The growth of wild rice subjected to increases in water
depth was analysed using growth curves and modelling techniques.
The growth of the plants in the control treatment was accurately
described by the logistic equation. Growth for plants
experiencing increases in water depth, for all phenological
stages studied, was also described by the logistic equation. The
derived parameters of K and r, in each phenological stage, were plotted versus water depth. Equations describing the resultant
relationship between r and Increases in water depth was
determined to be the same. This suggested that for wild rice the
maximum instantaneous rate of growth is constant. Thus, under
conditions of optimum nutrient levels, water depth increases have
the same effect on wild rice production during all phenologlcal
stages. | |
