Growth in controlled water regimes of three grasses common in freshwater wetlands of the southeastern USA

• Published in: Aquatic botany 1993, Vol.44 (4), p.345-359
• Main Authors: Kirkman, L.K., Sharitz, R.R.
• Format: Article
• Language: English
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Autoecology; Biological and medical sciences; Freshwater; Fundamental and applied biological sciences. Psychology; Leersia hexandra; Panicum hemitomon; Plants and fungi
• ISSN: 0304-3770; 1879-1522
• DOI: 10.1016/0304-3770(93)90076-9

Growth and drought tolerances of three common freshwater wetland grasses, Panicum hemitomon Schult., Manisuris rugosa (Nutt.) Kuntze, and Leersia hexandra Sw., were compared in experimental manipulations. Additionally, the effect of fire on the growth of P. hemitomon was examined. Rhizomes of these three perennial species were grown in small plastic pools under the following water treatments: (1) moist soil; (2) saturated soil (0 cm water depth); (3) inundated (13 cm water depth all year); (4) inundated-moist (13 cm water depth part of the year, followed by moist soil). Inundated plants of all species grew twice as tall as those in the moist soil treatment. This difference was interpreted as an elongation response to partial submergence. Under inundated conditions, stem elongation in M. rugosa was the same regardless of the water duration or depth. In P. hemitomon, stem heights varied with duration and depth of flooding: inundated > inundated-moist > saturated. For L. hexandra, mean stem height did not differ between inundated-moist and saturated water regimes. Mean above-ground to below-ground biomass ratio for L. hexandra was greater than that of either P. hemitomon or M. rugosa regardless of treatment. Panicum hemitomon produced no flowering stems under any of the treatments. For M. rugosa and L. hexandra, most flowering stems were produced under the inundated or saturated treatments. Winter fire, followed by the inundated or inundated-moist treatments, had a negative effect on emergence and overall growth of P. hemitomon, suggesting that winter stems are important for survival of this species. Relative drought tolerances, as measured by stomatal conductance and predawn xylem pressure potential, indicated least stomatal control by L. hexandra, followed by P. hemitomon and M. rugosa. Results suggest greater drought tolerance by M. rugosa and greater flood tolerance by P. hemitomon and L. hexandra.