Microtubers in yam germplasm conservation and propagation: the status, the prospects and the constraints

Abstract

The conservation of yam genetic resources using field genebanks, in vitro plantlets, pollen and seed storage are constrained by high losses and space requirements, maintenance cost and an irregular flowering, respectively. Microtubers produced from in vitro plantlets are proposed for conservation and propagation, as they have a longer shelf-life due to dormancy, and are also hardier and less bulky than plantlets. A lot of work has been done on microtuber production, especially the use of temporary immersion systems in production of larger, multiple microtubers. However, there have been different degrees of success, and, very few reports on microtuber dormancy. Also, research findings on postsprout management and efficiency of microtubers relative to other systems in terms of cost, ease of handling and savings on time are sparse. These research gaps limit the practical use of microtubers in conservation and propagation. Future research should be on dormancy control and post-sprout management. A microtuber to microtuber cycle for the conservation and propagation of yam germplasm is proposed in this review, and the invaluable potentials of microtubers in these regards is emphasised.