Effects of nitrate (2.0, 2.5, and 3.0 g L (1)) and salt (0.5, 1.0, 1.5. 2.0 g L(-1)) concentrations on biomass production by Spirulina platensis was examined in the Schlosser medium. The highest (p < 0.001) biomass yields and chlorophyll a content was observed at 2.5 g L (1) nitrate and 1.5 g L(-1) NaCl as 3.495 g L(-1) and 29.92 ring L(-1), respectively. Increment rate of biomass production was especially found between 72 and 216 h. Modified Richards, Schnute, Logistic and Gompertz models was successfully predicted (r(2) > 0.96 and RSS >= 0.003) biomass production by S. platensis as function of nitrate and salt concentrations. Low residual SLIM of squares (RSS) and high regression coefficients (r(2)) indicated that used models were well fitted to the experiment data and it could be regarded as sufficient to describe biomass production of Spirulina sp. Biological variables i.e. production rate (mu) and lag time (lambda) for S. platensis ranged 0.012-0.034 h(-1) and 2.43-5.85 h, respectively from biomass production were successfully predicted by modified Logistic model according to low RSS and F-testing value. (C) 2008 Elsevier Ltd. All rights reserved.