The GGBs continuously increased in size in all selected PGR combinations as well as in the PGR-free control (Table 4). The multiplication was clearly seen under the microscope by the formation of a solid mass of green tissue at the end of this test (Figure 1C). Single GGB was not well distinguished and could not be easily separated at this time, but multiple meristematic area developed and could be clearly seen on the surface or inner part of the GGB culture (Figure 1D). GGB multiplication was significantly better for the 2.22มิวM 2ip, 2.22มิวM 2ip + 5.37 มิวM NAA treatments and the PGR-freecontrol (Table 4).