Mitchell, Sylvia A.; Ahmad, Mohammed H.
Author Affiliation, Ana.
An improved micropropagation system of yam (Dioscorea spp.) for the commercial production of elite planting material
Jamaican journal of science and technology
Date of Publication
Seven species of yam (genus Dioscorea) are extensively cultivated. Expansion is hindered by low multiplication rates, diseased planting material, inefficient cultural practices and post-harvest losses. A rapid micropropagation system for D. trifida cv SNY and D. cayenensis cv RLYY was developed to alleviate these hindrances, with results that are applicable to other yam species. Initiation was reliably obtained using nodal explants from young vines cut from minisetts, leafy cuttings or small tubers. Shoot growth increased and medium browning decreased when PPO inhibitors were added to the media. Shoot production was highest on BM and 0.5 mg L-1 BAP adjusted to pH6 for SNY and pH4 for RLYY. Rooting was highest on BM with IBA. A simple cost-effective hardening method was devised. Slow-growing juvenile-like (type I) and faster-growing adult-like (type II) growth were identified in vitro and ex vitro. Type II shoot production increased as the in vitro multiplication rate increased; a decrease in the type I growth phase ex vitro resulted in increased tuber production. Tubers (Ro) were harvested from RLYY plantlets after 9 months (1.9 = 100 g/plant) and SNY plantlets after 7 months (4.4 = 40g/plant). Leafy cuttings of RLYY yielded 1.3 Ro tubers (74g/plant). R1 tubers averaged one (1422 g) per RLYY plant or 13.0 tubers (521 g) per SNY plant. Sprouting of RLYY minisetts cut from R1 tubers was high (95% after 5 weeks). The COP of this improved micropropagation method, is lower than for the minisett system. The significance of these results to yam production in Jamaica is discussed.....