Effect of various growth regulators on growth of yam (Dioscorea trifida L.) in vitro shoot tips

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.