Effects of Earthworms and Substrate on <i>Iris pseudacorus</i> Growth

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.