Rapid in vitro germination of zygotic embryos of fluted pumpkin (Telfairia occidentalis Hook. f.)

Abstract

SummaryFluted pumpkin, Telfairia occidentalis, is becoming an important regional vegetable for its food and medicinal uses. The recalcitrant nature of its seed makes conservation difficult and in vitro techniques may be a viable option for conservation. A pilot study was conducted on the effects of different concentrations of a commercial bleach [3.85% (w/v) sodium hypochlorite] for surface sterilisation of T. occidentalis seed. The optimum concentration [25% (v/v)] was then used as a basis to investigate the responses of mature embryonic axes of T. occidentalis to different concentrations of kinetin (Kin; 0, 1.0, or 2.0 mg l–1) and 1-naphthaleneacetic acid (NAA; 0, 0.5, or 1.0 mg l–1) combined in a factorial design. The results of the first experiments indicated that commercial bleach at 25% (v/v) resulted in the lowest contamination of explants (10%), with no evident injury to the embryonic axes. The results revealed that root emergence started 3 d after initiation (DAI) only on Murashige and Skoog medium (MS) with no added plant growth regulator (PGR), and that, by 12 DAI, all media supported the rooting of explants. The highest rooting percentage (69%) was observed at 15 DAI on MS medium with 0.5 mg l–1 NAA, without Kin. However, shoot emergence started at 9 DAI on PGR-free MS medium, on MS with 0.5 mg l–1 NAA, or on MS plus 1.0 mg l–1 Kin. The highest shooting percentage (91%) of explants was observed with 0.5 mg l–1 NAA at 21 DAI. Considering all other growth parameters, MS medium supplemented with 0.5 mg l–1 NAA was found to be best for the germination of embryonic axes of T. occidentalis.