A worse diameter growth was obtained using the medium with only NAA supplement either at 5.37 มิวM or 26.85 มิวM (without cytokinin), which exhibited the requirement of cytokinin for GGB multiplication. Undesired sporophyte growth was also seen in this multiplication experiment, especially for the "Control" and 5.37 or 26.85 มิวM NAA. However sporophyte growth was not seen in the combination of 2.22 มิวM ฺฤ + 5.37 มิวM NAA, which only led to an intermediate level of GGB multiplication. This result strongly suggests that just a low level of BA may completely inhibit sporophyte development.