Alternative manifestations in origin form, and function of the primary nodal complex of yams (Dioscorea spp.): A review. (77)

Lawrence A. Wilson, Lynda D. Wickham, Theodore Ferguson


The involvement of the yam 'head' or primary nodal complex (PNC) in several traditional practices for yam propagation, cultivation, and storage is outlined. Alternative phylogenetic and ontogenetic manifestations of the PNC, including those of different species which produce germinating seedlings and sprouting stem cuttings, bulbils, tuber pieces, and whole tubers with 'heads'), as well as those in bulbil development are described. Failure to recognize the similarity of this unique organ in its different manifestations may have restricted the scope of research investigations for yam improvement. Previous Investigations on micro-tuber production in tissue culture for distribution of disease-free germplasm, minisett techniques for production of planting setts and mini-ware tubers, and GA3 application for extension of tuber dormancy and storage life are described. It is suggested that development of improved techniques for combination of minisett production and GA3-induced enhancement of tuber storage life could lead to recognition of mini-tubers as a new staple tropical product, comparable and competitive with Solanum tuberosum in production, quality, and international utilization as a table tuber.


Primary nodal complex; Yam head; Manifestations in Dioscorea spp

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