Glufosinate ammonium is a herbicide that can be used to select transformed plant cells that express the bar gene. The concentration of glufosinate ammonium that is ideal for setting transformed calli of rice will depend on several factors, including the specific transformation method used, the efficiency of transformation, and the sensitivity of the plant cells to the herbicide.

Generally, a concentration of glufosinate ammonium in the range of 0.1-1.0 mM is effective for selecting transformed calli of rice expressing the bar gene via pCAMBIA1301. However, it may be necessary to test a range of concentrations to determine the optimal concentration for your specific transformation system and plant cells.

It is essential to use the lowest concentration of glufosinate ammonium, which is effective for selection, as higher concentrations can be toxic to plant cells and may negatively impact the growth and development of the transformed calli. It is also essential to carefully follow the manufacturer's instructions for use and to handle the herbicide safely, as it can be toxic to humans if ingested or absorbed through the skin.