Mass propagation and conservation of Daffodil Orchid (Ipsea speciosa)

Abstract

Experiments were carried out to identify the correct maturity stage for in-vitro seed germination and to develop an in-vitro protocol for mass propagation of Ipsea speciosa an endangered orchid species. After hand pollination of the flowers, the pod length, girth and color changes of pods were observed at weekly intervals in order to determine the morphological indicators of maturity. For In-vitro seed germinatio , pods were collected 4,6,8 and 10 weeks after pdllination on nine different media viz l.MS 2. MS (Murasinghe & Shoog) medium 2. MS with PVP (2g/L) 3. MS with charcoal (2g/L) 4. KNC (Knudson C medium) 5.KNC with PVP (2g/L) 6. KNC with charcoal (2g/L) 7. KNC with banana extracts (75g/L) 8. V&W (Vacin & Went medium) 9. V&W with banana extract (75g/L) and coconut water (150ml/L) were tested. Growing rhizome tips and rhizome parts were used as explants in in-vitro vegetative propagation experiments and MS medium with charcoal (2g/L) and without charcoal were used as establishment media. After establishment, different combinations of NAA and BAP were tested to induce shoot proliferation. Three different potting media (l.sand: compost (1:1) 2. Coir dust 3. Compost: top soil (1:1) were tested for acclimatization of in-vitro raised plantlets. Survival rate was observed in weekly intervals. Results revealed that seeds enclosed within pods collected eight weeks after pollination was the best stage for in-vitro seed germination of I. speciosa. 100% germination was observed on MS medium with PVP and charcoal, KNC with banana extract and V&W with banana extract and coconut water. Eight- week-old pods took 20 days to germinate whereas ten-week -old -pods took 60 days to germinate at a rate of 50%. Growing rhizome tips were identified as the best explant source for culture establishment on MS medium with charcoal 0.5 mg/L BAP + 5mg/L NAA gave rise to the highest proliferation rate (1: 6). The most suitable potting medium for acclimatization of in-vitro raised plantlets was found to be compost and top soil (1:1) in which 80% survival rate was observed