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6 In vitro corm formation and flowering and ex vitro
acclimatization
6.1 INTRODUCTION
In vitro formation of storage organs increases the ex vitro survival rate during
acclimatization and these organs serve as a more attractive product than seeds, as
flowering of the plant can be enjoyed at a much earlier stage (ASCOUGH et al.,
2009). Commercialising in vitro produced corms of R. sabulosa will also reduce the
pressures on the vulnerable populations from which seeds are harvested
(RAIMONDO et al., 2009).
In vitro flowering is an important tool in ornamental plant breeding, as it enables the
breeder to see the floral traits in a much shorter time than in ex vitro conditions.
Some factors that influence in vitro flowering and ex vitro survival is discussed in
section 2.10 and 2.8.9 of Chapter 2 respectively.
The aims of this Chapter were to establish an in vitro corm induction protocol for R.
minutiflora, R. leipoldtii and R. sabulosa, to investigate the effect of some physical
and chemical stimuli on in vitro flowering of R. minutiflora and R. sabulosa corms and
to establish an ex vitro acclimatization protocol for R. minutiflora and R. sabulosa
corms and plantlets.
6.2 MATERIALS AND METHODS
6.2.1 Corm formation
In all experiments, the in vitro generated shoots were separated from each other,
trimmed to 25 mm and all roots were removed for uniformity. If not stated otherwise a
MS medium supplemented with 100 mg.l -1 myo-inositol and 3% sucrose, with pH
adjusted to 5.7 and solidified with 0.8% agar was used. All experiments were
conducted in a laminar flow hood and cultures were placed in a growth chamber
under 3.4 µmol m –2 s –1 light using Osram ® 75 W cool white fluorescent tubes with a
16/8 light/dark photoperiod. The duration of all experiments was 6 months, as no
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