INTERACTIONS BETWEEN ENVIRONMENTAL VARIABLES ON GROWTH-RATE AND CARRAGEENAN CONTENT OF SOLIERIA-CHORDALIS (SOLIERIACEAE, RHODOPHYCEAE) IN CULTURE

Using vegetative propagules (ramuli) of the iota-carrageenan producing red seaweed Solieria chordalis, a maximum growth rate of 6.8% d(-1) was achieved when cultured at 20 degrees C and 100 mu mol photon m(-2) s(-1) in seawater supplemented with 20 mu M NO3-N or 10 mu M NO3-N plus 10 mu M NH4-N. Ramuli grew less well when nitrogen was supplied solely as NH4+. Maximum carrageenan content was observed at the same temperature, irradiance and salinity as growth, but at lower nitrogen concentrations. These findings are discussed in relation to results obtained from studies on other iota-carrageenan producing carrageenophytes.