No abstract

The response of Iris pseudacorus to the introduction of earthworms and to a variety of substrates in constructed wetland systems was investigated under greenhouse conditions. The growth of I. pseudacorus was influenced by the presence of earthworms and the type of substrate. Plants grown on a sand substrate had the fewest seedlings and the smallest plant size. Because the sand substrate started with the lowest nutritional value, the addition of earthworms resulted in the largest increase in fresh and dry weights of I. pseudacorus, when compared with the other pairs of substrate treatments, with or without earthworms. The addition of earthworms increased pod production in I. pseudacorus, especially on substrates of mixed sand and soil, and with mixed sand and organic matter. Pod production in I. pseudacorus pots with earthworms varied by substrate.

The response of growth characteristics (tillering number, plant height, stem diameter, leaf length, and leaf width), and nitrogen (N) and phosphorus (P) concentration of three wetland plants to the introduction of earthworms in a constructed wetland (CW) was investigated under greenhouse conditions. The growth characteristics, and N and P concentration of wetland plants were influenced by earthworms. The addition of earthworms enhanced three wetland plants growth, especially benefiting to the flower formation of the C. indica. The addition of earthworms to CW, the increased rate of plant height, stem diameter, leaf length, and leaf width could be summarized as follows: C. indica > P. australis > T.augustifolia. N and P concentration of Stems, leaves and flowers of wetland plants was increased by addition of earthworms into constructed wetland, and N and P concentration distributed in wetland plants followed the order of flowers> leaves > stems. The N and P removal rate could be enhanced by addition of earthworms into constructed wetland.