Effects of a wide range of concentrations of four salts (NaCl, KCl, MgCl2, CaCl2) and different pHs (pH 4.5, 5.0, 5.7, 6.2) on colony formation, were investigated in protoplast culture of mangrove, Bruguiera sexangula, suspension cells. The results were compared to those obtained with protoplasts of tobacco BY-2 cells and leaf protoplasts of Populus alba. A 96-multiwell culture plate method was used and only 250 to 2500 protoplasts in 55 μl medium were sufficient to test the effect of each treatment. The effects of four salts were always found to inhibit colony formation of Populus and tobacco protoplasts at pH 5.7. In contrast, MgCl 2 and CaCl2 stimulated further development of B. sexangula protoplasts, while KCl had an inhibitory effect. The highest number of colony formation was obtained at pH 5.7 without salt additions. However, at lower pHs, some stimulatory effects were found at low concentrations of all four salts tested. Depending on the pHs, different patterns of stimulation and inhibition of four salts were obtained in B. sexangula protoplasts.