By adding a liquid medium (20 ml) on top of a final stage
solid medium (initially 100 ml), subculturing can be avoided. This can
lower the cost. The system is used :
during stage 2 for plants requiring a long subculture period
(e.g. orchids, one subculture takes 6 months, fresh medium is added after
3 months);
in the final stages to induce elongation and/or rooting.
Table: Effect of the double layer system on the growth of Cordyline
terminalis
Treatment
Average weight per container
(g)
Average number of shoots
> 2.5 cm
Average shoot weight (g)
at transplanting
Average shoot weight (g)
4 weeks after transplanting
Stage 2 culture transferred
on a fresh stage 3 medium
23.3 ± 5.5
22.4 ± 5.5
0.139 ± 0.013
0.174
Stage 2 culture in wich a
liquid stage 3 medium was added
28.0 ± 1.6
51.4 ± 6.9
0.191 ± 0.022
0.269
Classical ingredients of a double layer medium are:
