Effect of boron and calcium on growth and nitrogen fixation of the blue-green algaCalothrix parietina

Effects of boron and calcium on the blue-green algaCalothrix parietina were determined. There was a significant decrease in growth, chlorophylla, saccharide and total nitrogen fixed under Ca²⁺ and boron deficiency. The addition of boron at different concentrations to Ca²⁺-deficient cultures led to partial recovery of these parameters. Calcium addition to B-deficient cells led to a partial recovery of growth, saccharide, chlorophylla and total nitrogen fixed. At high concentrations of calcium these parameters were significantly inhibited. The data also revealed that the different responses to B concentrations were due to the Ca²⁺ level in the medium.