Establishment of three emergent macrophytes under different water regimes

The behavior of three emergent aquatic macrophytes under different water regimes was studied with the aim of achieving reconvertion of degraded wetlands and wetland construction for water quality improvement. Scirpus californicus, Typha subulata and Zizaniopsis bonariensis establishment was evaluated under a split plot design, in a factorial experiment with three levels of a water regime factor over a subsoil substratum. The stagnant 10 +/- 2 cm water level was best suited to T. subulata and Z. bonariensis development and S. californicus developed better at oscillating water level (3 +/- 2 cm) with flooding at 48 hour intervals. The morphological response variables (thickness and width at half length of the tallest leaf or stem per plant, height of tallest leaf or stem per plant, number of green leaves or stems and number of shoots per plant, and survival of propagules' original leaves or stems) were satisfactory descriptors to differentiate (p<0.1%) growth of above ground parts as related to water regimes and species. The three species did survive satisfactory in subsoil-like substratum under the tested water regimes. Mortaiity was in the worse case, 17.2%, 36.7%, and 9.4% for S. californicus, T. subulata, and Z. bonariensis, respectively. Although Z bonariensis growth was very poor, only S. californicus and T. subulata could be indicated for planting under similar limiting conditions. (C) 1999 Published by Elsevier Science Ltd on behalf of the IAWQ. All rights reserved.