Abstract

In this work, we observed the effect of hormonal content of four culture media on the growth of Dioscorea trifida shoot tips. Medium S included 0.6 µM 6-benzylaminopurine, 1.07 µM naphthalene acetic acid, and 0.23 µM gibberellic acid (GA₃), medium EBR 0.1 µM 24-Epibrassinolide and 0.23 µM GA₃, medium T 25 μM meta-topolin and 0.23 µM GA₃ and medium ZR 25 μM zeatin riboside and 0.23 µM GA₃. After 2 months in culture, shoot length was highest on medium EBR and ZR, with values of 11.63 and 11.30 mm, respectively, intermediate on medium S (9.70 mm) and lowest on medium T (3.07 mm). Oxidation reached a similar level on medium S, T and ZR (2.17 - 2.40) while it was only 1.63 on medium EBR. Well-developed shoots were obtained on medium EBR with an average of 1.93 leaves and 0.70 roots per shoot. Shoots were less developed on medium S and ZR, with an average of 1.30 leaves and 0.20 roots per shoot on medium S and 1.60 leaves and 0.00 roots per shoot on medium ZR. On medium T, buds showed a tuberized aspect and no leaves or roots were produced. In conclusion, medium EBR proved superior to the three other media tested based on the parameters tested.

Key words: Yam, Dioscorea trifida, shoot tip growth, 6-benzylaminopurine, 24-Epibrassinolide, meta-topolin, zeatin riboside.