Distribution of food reserves in Dioscorea dumetorum (Kunth) Pax tubers during sprouting

The distribution of starch, ethanol-soluble sugars, lipid and protein in the tubers of Dioscorea dumetorum var, funfun (white variety) and D. dumetorum var. pupa (deep yellow variety) was investigated during sprouting. The distribution patterns of the food reserves were the same in the two varieties. There were variations in the distributions of food reserves in the ‘head’, ‘middle’ and ‘tail’ regions of the tubers, but physiological dominance was not observed. Starch and lipid decreased from planting to leaf flush, whereas ethanol-soluble sugar increased from planting and reached a peak just before sprout initiation. Similarly, protein increased until after sprout initiation and then decreased. The food reserves increased after leaf flush. At planting, starch was the most abundant food reserve. This was followed in order by protein, lipid and sugar. During sprouting, protein was the most abundant. These findings are discussed in relation to sprouting in D. dumetorum tubers.