The influence of convective flow and sediment type on root morphology in Typha domingensis

A pond experiment was conducted to examine the influence of convective flow on root morphology of Typha domingensis plants grown in either sand, clay or a 50:50 mixture of the two sediments. The sediment types had different m ean redox potentials; +14.6, -253 and -160mV, respectively. To prevent conv ective flow in treatment plants, the leaves were pierced above the water su rface twice weekly throughout the experimental period. Plants responded to both leaf piercing and sediment type but in different ways. The mean root l ength of intact plants was 11.5-30.5% greater than in pierced plants whilst the mean root surface area of intact plants was 39.8-54.8% greater than in pierced plants. In both cases, the greatest percentage difference was foun d in plants growing in sand. Other characteristics, including biomass and i ts allocation, responded to sediment type but not leaf piercing with plants growing more vigorously in clay. The morphology of the plants varied betwe en the sediments. Based on the lacunal cross-sectional area, plants growing in clay had the greatest capacity for oxygen transport. (C) 2001 Elsevier Science B.V. All rights reserved.