The independent effects of ferrous and phosphorus on growth and development of Tetraselmis suecica; an in vitro study

Five treatments including Conway medium, media containing 0.1, 0.17, 0.3 and 0.5 mg l-1 ferrous (Fe; in the first experiment), media with 1, 1.26, 1.59, 2 mg l-1 concentrations of phosphorous (P; in the second experiment) and a pure sample of Tetraselmis suecica were cultured under laboratory conditions. Growth rate of the algae was determined using the optical density method at 750 nm and number of algal cells were counted with a hemocytometer. The results of the first experiment showed that the amount of Fe for maximum growth of this species was 0.3 mg l-1, while Fe concentration in Conway medium was 0.27 mg l-1 (P>0.05). The results of second experiment showed that 1.59 mg l-1 P caused the maximum growth of algae which was not significantly different from that of the control medium (with 1.6 mg l-1; Conway; P>0.05). These results showed that due to the lack of significant differences in maximum growth of this alga recorded in 0.3 mg l-1 Fe and that recorded in 1.59 mg l-1 P in Conway medium, increase or decrease of these doses will have a significant negative effect on algal growth.