Stage 2

Induction of meristematic centres and a fast propagation. A commercial system can become profitable starting from a multiplication ratio of 2 per month. In Fig. 1 the theoretical yearly production is shown for a monthly multiplication rate of 2 and 4.

Fig. 1. Theoritical number of plants that can be produced in 1 year
when the multiplication rate should be 2 (A) or 4 (B) per month

For most micropropagation systems axillary branching is favored.
In advanced systems embryos, adventitious buds, nodules,
meristematic clusters, retarded shoots can be used. In the
following schemes node culture and shoot tip cultures are illustrated.

Node culture

Shoot tip culture

A fast propagation rate, mainly by the use of high concentrations of cytokinins, can create problems: hyperhydricity, bushiness, somaclonal variation, rooting problems, delay of flowering, … Therefore the interventions in stage 2 should never mortgage the successive stages.

Example: multiplication of rose cultures