In vitro sucrose concentration influences microtuber production and diosgenin content in white yam (Dioscorea rotundata Poir)

SUMMARYYam minisett technique (YMT) has been promoted throughout West Africa since the 1980s as a sustainable means of producing clean yam planting material, but adoption of the technique is often reported as being patchy at best. While there has been much research on the factors that influence adoption of the technique, there have been no attempts to assess its economic viability under ‘farmer-managed’ as distinct from ‘on station’ conditions. The present paper describes the results of farmer-managed trials employing the YMT (white yam: Dioscorea rotundata) at two villages in Igalaland, Kogi State, Nigeria. One of the villages (Edeke) is on the banks of the River Niger and represents a specialist yam environment, whereas the other village (Ekwuloko) is inland, where farmers employ a more general cropping system. Four farmers were selected in each of the two villages and asked to plant a trial comprising two varieties of yam, their popular local variety as well as another variety grown in other parts of Igalaland, and to treat yam setts (80–100 g) with either woodash or insecticide/nematicide+fungicide mix (chemical treatment). Results suggest that while chemical sett treatment increased yield and hence gross margin compared with woodash, if household labour is costed then YMT is not economically viable. However, the specialist yam growers of Edeke were far more positive about the use of YMT as they tended to keep the yam seed tubers for planting rather than sell them. Thus, great care needs to be taken with planning adoption surveys on the assumption that all farmers should adopt a technology.

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In vitro Conservation and Cryopreservation of Nandina domestica, an Outdoor Ornamental Shrub

Notulae Botanicae Horti Agrobotanici Cluj-Napoca ◽

10.15835/nbha4129335 ◽

2013 ◽

Vol 41 (2) ◽

pp. 638 ◽

Cited By ~ 4

Author(s):

Aylin OZUDOGRU ◽

Diogo Pedrosa CorrÃªa Da SILVA ◽

Ergun KAYA ◽

Giuliano DRADI ◽

Renato PAIVA ◽

...

Keyword(s):

Liquid Nitrogen ◽

Storage Temperature ◽

Sucrose Concentration ◽

Aluminum Foil ◽

Shoot Tips ◽

In Vitro Conservation ◽

Shoot Cultures ◽

Storage Medium ◽

Droplet Vitrification

The study focused on an economically-important ornamental outdoor shrub, Nandina domestica, with the aims to (i) optimize an effective in vitro conservation method, and (ii) develop a cryopreservation protocol for shoot tips by the PVS2 vitrification and droplet-vitrification techniques. For in vitro conservation of shoot cultures, the tested parameters were sucrose content in the storage medium (30, 45, 60 g/L) and storage temperature (4 Â°C or 8 Â°C). Cryopreservation was performed by applying the PVS2 vitrification solution, in 2-ml cryovials or in drops over aluminum foil strips, for 15, 30, 60 or 90 min at 0 Â°C, followed by the direct immersion in liquid nitrogen of shoot tips. Results show that N. domestica shoots can be conserved successfully for 6 months at both the temperatures tested, especially when 60 g/L sucrose is used in the storage medium. However, conservation at 4 Â°C showed to be more appropriate, as hyperhydricity was observed in post-conservation of shoots coming from storage at 8 Â°C. As for cryopreservation, a daily gradual increase of sucrose concentration (from 0.25 to 1.0 M) produced better protection to the samples that were stored in liquid nitrogen. Indeed, with this sucrose treatment method, a 30-min PVS2 incubation time was enough to produce, 60 days after thawing, the best recovery (47% and 50%) of shoot tips, cryopreserved with PVS2 vitrification and droplet-vitrification, respectively.

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