Biological Characters of Tetraploid Dioscorea zingiberensis

Artificial induced tetraploid of Dioscorea zingiberensis C.H.Wight was used as material for biological observation and cross hybridization with natural diploid. The tetroploid displayed normal morphology but their develop period was delayed as compared to natural diploid in field. Biennial tertraploid plant differentiated into male type and female type. Both sexual types possessed fertility as indicated by pollen activity (41%) and seed set ability after pollination.Reci-procal cross between the tetraploid and diploid produced 8.2% and 6.3% seed setting, respectively. Offspring of the cross pollination between male and female tetraploid was examed to be tetraploid. These results indicated the artificial induced tetraploid had stable ploidy and lower fertility.