EFFECTS OF NITRATE CONCENTRATION ON THE GROWTH AND PHYSIOLOGY OF <i>LAMINARIA SACCHARINA</i> (PHAEOPHYTA) IN CULTURE^1,²

Abstract

ABSTRACT Laminaria saccharina Lamour. sporophytes were grown in enriched and synthetic media through a range of nitrate concentrations, There was an approximately linear relationship between growth and nutrient concentration up to 10 μ substrate concentration. The half‐saturation constant (K 2) was ca. 1.4 μ NO3‐. The internal levels of NO3‐ increased at substrate concentrations above 10 μM b&gt;3‐ and reached levels several thousand times higher than the surrounding medium. Thus there is evidence for luxury consumption of NOsb&gt;3 ‐ . The chlorophyll content and photosynthetic capacities of plants also increased with increasing external NO 3 ‐ The ecological implications of this work are considered .