ENVIRONMENTAL CONTROL OF THE SEASONAL GROWTH OF THE SUBMERSED AQUATIC MACROPHYTE LOBELIA DORTMANNA L.

Abstract

Leaf growth, photosynthesis and soluble carbohydrate content were measured for Lobelia dortmanna L. across one year in a small oligotrophic lochan in the northwest of Scotland at a number of sites, varying in degree of exposure, sediment type, nutrient concentrations and plant form. Leaf production and loss occurred during the entire year, although production and photosynthesis were maximal in the early summer. Soluble carbohydrate was highest in the early spring, and was lowest when leaf production was greatest. Environmental changes (solar irradiance, lochan temperature and water levels) were also related to growth rates, showing a particularly strong correlation between irradiance and the relative leaf growth rate. Little influence of epiphytes or limitation of growth by nutrient or the contribution of inorganic carbon was found. Copyright © 1987, Wiley Blackwell. All rights reserved