After adequate shoot growth, the next stage in plant tissue culture is growth of functional roots in the shoots or rhizogenesis. Clumps of growing shoots are collected from shoot growth medium and excised with sterile scalpel blades into individual shoots or in small group of shoots and aseptically transferred to another medium, which triggers root formation. There are two major triggers for shoot formation. The first is - reducing the concentration of cytokinins and increasing the concentration of auxins. The second trigger is lowering of mineral and organic nutrient content in the medium. So, in some cases, MS medium in half strength or one-fourth strength is used as root initiation medium. 

 

The following table elucidates the plant growth promoters used by different authors for rhizogenesis from in-vitro grown adventitious shoots. The complete rhozogenesis process takes about 2 - 3 weeks. The preferred culture condition in terms of temperature, humidity, light intensity and photoperiod is sililar to that used in adventitious shoot growth stage.