Effect of some phytohormones on growth characteristics of Chlorella sorokiniana IAM-C212 under photoautotrophic conditions

The effects of some phytohormones [indole acetic acid (IAA), indole butyric acid (IBA), gibelleric acid (GA3), and kinetin] on cell dry weight, cell number, cell size, protein and chlorophyll contents of Chlorella sorokiniana IAM-C212 were investigated under photoautotrophic conditions. Treatment with IAA (15 mg/l) and IBA (15 mg/l) resulted in significantly higher dry cell weight and cell number than the control (P 0.05). The protein contents of the cells cultivated with 20 or 10 mg/l of GA3, 15 mg/l of kinetin, and 15 mg/l of IBA or IAA were 46.64, 45.83 and 45.81%, respectively. In the control experiment, the protein content was 43.38% after eight days of cultivation, showing that treatment with these phytohormones had no significant effect on the protein contents of the cells (P > 0.05). Combination of IBA and GA3 exhibited synergistic effect on growth and productivity of C. sorokiniana but there was no synergistic effect when IAA was combined with either GA3 or kinetin.    Key words: Phytohormones, Chlorella sorokiniana, cell growth, cell size, protein content, chlorophyll content.