Abstract:
Chrysanthemum {Chrysanthemum morifolium) is one of the most important flower spp.
in commercial floriculture. Tissue culture is a useful propagation tool for mass
production of planting material and for induction of new genotypes via somaclonal
variation.
In this study, an attempt is made to perfect tissue culture protocol for micro propagation
of Chrysanthemum cv. Tension and to assess somaclonal variation and morphogenic
potential in different explants. The procedure involved two phases as direct
organogenesis and indirect organogenesis. Under direct organogenesis aseptic culture
of shoot tips was followed by rapid shoot multiplication, rooting and finally hardening
and establishment of plantlets in soil. All stages were arranged in Completely
Randomized Design with 10 replications. The agar-solidified MS medium
supplemented with 0.2 mg/1 BAP was given highest shoot multiplication rate (11.7
shoots/explant). Maximum in vitro rooting (13.2 roots/plant) was achieved with MS
containing lmg/1 IB A with 0.5g/l charcoal. Plants acclimatized successfully in
greenhouse environment with survival rate of 80%.
Under indirect organogenesis explants of leaf, shoot tip and stem segments were
cultured aseptically and followed by callus initiation, shoot regeneration and up to
establishment of plantlets in soil. Although highest callus formation was observed with
immature leaves in MS medium supplemented with 0.3mg/1 2, 4-D, highest
regeneration capacity was observed in callus derived from shoot tips and stem segments
in the same medium. Significantly higher rate of proliferation (4plants/explant) was
achieved, in MS medium supplemented with 0.5mg/l BAP and 0.5mg/l NAA.
Somaclonal variation was assessed through phenotypic makers on chrysanthemum
leaves pertaining to morphological variations which record 8% variation as compared
to mother plant. Variation in flowers couldn’t be investigated as the period of study was
not sufficient to reach the blooming stage of chrysanthemum plants raised from tissue culture technology. In-vitro rooted plantlets were successfully established in medium
containing top soil cattle manure ands sand at a ratio of 1:1:1 with 85% survival rate.
Hence valuable cultivars such as Tension can be easily propagated in vitro using shoot
tip and stem explants as they exist higher in- vitro morphogenic potential.
