Standardisation of explant for In vitro propagation in Dendrobium spp .
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Date
1992
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Department of Horticulture (Pomology, Floriculture and Landscaping) , College of Horticulture, Vellanikkara
Abstract
Investigations were carried out at the Plant Tissue Culture Laboratory attached to All India Co-ordinated Floriculture Improvement Project (AICFIP), College of Horticulture, Vellanikkara, during 1990-91 to standardise the explants for in vitro propagation in Dendrobium spp.
The explants used for the study were shoot tip, axillary bud, inflorescence stalk, leaf segments and root segments. The species of ' Dendrobium used were D. fimbriatum, D. moschatum and D. nobile. For culture establishment, proliferation of shoot/callus and _in vitro rooting studies, different sources of auxins (NAA, IBA, 2,4-D) and cytokinins (BA, KIN) were used with KC, MS and/or VW media.
In all the explants, surface sterilization using 0.1 per cent mercuric chloride for 10 minutes was found to be the best. The explants collected during April recorded the minimum rate of contamination and the maximum survival percentage. Axillary bud was found to be the ideal explant for enhanced release of axillary buds.
For Dendrobium moschatum, MS medium with the treatment combination of NAA 1.5 ppm + BA 1.0 ppm was found to be effective in influencing early bud initiation and elongation, but for D. fimbriatum and D. nobile, VW medium containing NAA 1.5 ppm +' BA 1.0 ppm was found to be the best. When the cultures were subjected to shoot . proliferation, VW medium containing NAA 2 ppm + BA 3 ppm gave maximum number of shoots in D. fimbriatum (18.8), D. moschatum (10.8) and D. nobile (7.6). The shoots produced at this level were well elongated and healthy. The proliferation of shoots also increased when NAA 2 ppm + KIN 3 ppm were used in VW ‘medium, but the number of shoots produced was: low, compared to NAA 2 ppm + BA 3 ppm. BA was found to be more efficient than KIN for the induction of axillary shoots.
Addition of CW (15%) into the basal proliferation medium increased the number of shoots in all the three species of Dendrobium.
Axillary shoots produced per culture vessel increased at a mean rate of 8.3, 7.7 and 6.6 shoots per subculture in D. fimbriatum, D. moschatum and D. nobile, respectively.
For in vitro rooting, MS (half strength) medium containing IBA 4 ppm was found to be the best. Addition of sucrose at 1.5 per cent and AC at 0.10 per cent enhanced the rooting' of the shoots produced in vitro .
Of the various ex plants tried for somatic organogenesis (callus mediated), root segments (aerial as well as from culture) was found to be the best explant in initiating callus. In the culture establishment, swelling of the explant was observed in modified VW medium containing NAA 4 ppm + BA 1 ppm. As regards callus induction, 2,4-D at 2,0 ppm in modified VW medium was found to be better for all the explants. Maximum callusing (Cl = 240) was observed in root from culture. Efforts to induce organogenesis were not successful.
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