This is because plant tissue culture is different from the growth of plants under natural conditions, and all kinds of essential or non-essential substances must be obtained from the culture medium, and plant hormones, as an organic substance produced by plant metabolism, have obvious physiological effects at extremely low concentrations. Because the growth of plant cells in the culture medium is limited by the environment, it is impossible to synthesize enough phytohormones to meet their own growth, so in order to meet the needs of tissue growth, phytohormones must be added.

Hormones that need to be added in plant tissue culture include auxin: IAA, CTKs, and 18 mineral nutrition needed for plant growth. In production: we can also use these substances instead: 6-BA, IBA, NAA, 2,4-D, JA, etc.