Abstract: Changes in sugar composition occur continuously in plants tissues, at different develop-mental stages. Tuber dormancy induction, stability, and breaking are very critical developmental transitions in yam crop production. Prolonged tuber dormancy after physiological maturity has constituted a great challenge in yam genetic improvement and productivity. In the present study, biochemical profiling of non-structural sugar in yam tuber during dormancy was performed to determine the role of non-structural sugar in yam tuber dormancy regulation. Two genotypes of white yam specie; one local genotype (Obiaoturugo) and (TDr1100873) were used for this study. Tubers were sampled at (42, 56, 87, 101, 115, and 143) days after physiological maturity (DAPM). Obiaoturugo exhibited a short dormant phenotype and sprouted at 101DAPM, whereas TDr1100873 exhibited a long-dormant phenotype, and sprouted at 143DAPM. Significant metabolic changes were observed in non-structural sugar parameters, dry matter, and moisture content in Obiaoturugo from 56DAPM, whereas, in TDr1100873 significant metabolic changes were observed from 101DAPM. It was observed that the onset of these metabolic changes occurred at a point when the tubers of both genotypes exhibited dry matter content of 60%, indicating that dry matter content of 60% might be a critical threshold for white yam tuber sprouting. Nonreducing sugars increased by 9-10-fold during sprouting in both genotypes which indicates its key role in tuber dormancy regulation in white yam. This result implies that some key sugar metabolites can be targeted for dormancy manipulation of yam crop.