Effects of iron on growth, degree of pigmentization and nitrogen assimilation in Skeletonema costatum

The effects of iron and the interaction between iron and nitrogen on the growth, degree of pigmentization and nitrogen assimilation of S. costaturn are studied. The results show that with the increase of iron concentration from 3×10^-8 to 5×10^-6 mol/dm³, nitrogen uptake and assimilation by the alga increased, the degree of cytopigmentization reduced, and content of intracellular amino acid (PAA) and protein raised (Pr).Cell growth rate was the highest at 5×10^-6 mol/dm³ Fe Chlorophyll a, thaeo-pigments, PAA and Pr were all related to logarithmic iron concentration. It was also found that the interaction between iron and nitrogen had a marked effect on the growth, degree of pigmentization and nitrogen assimilation at N/P=20:1 (by comparison with N/P=40:1 and 10:1).At given iron concentration, the effects of different specific N source on the rate of transferring PAA to Pr at the N source of lower oxidized state were more marked than at the N source of higher oxidized state.