Effect of two cytokinins in combination with acetic acid α-naphthalene on yams ( Dioscorea spp.) genotypes’ response to in vitro morphogenesis

The effect of two growth regulator combinations was studied on the morphogenesis in vitro of 3 genotypes of yams ( Kounondakou , Gnon-boya and RB 89579 ). Benzyl aminopurin (BAP) and zeatin (ZEAT) were tested, respectively at a concentration of 0.5 mg/l with the galzy glutamine basic medium containing naphtalene acetic acid (NAA) (0.5 mg/l). Stem fragments were used as explants. The number of stripped buds and explants having stem and roots are sampled after 2 weeks in culture. The dry matter content, the number of roots and leaves and the height of each young sprout were determined after 5 weeks in culture. The results obtained indicated that no break in leaf growth was observed on the control medium (without cytokinin) but media with BAP and zeatin presented a good plants aerial part development. A significant interaction (p < 0.05) was observed between the genotypes and the type of cytokinin. However, the highest bud sprouting and shoot development were obtained with BAP. Thus, BAP can be considered as cytokinin having a good morphogenic aptitude when compared to zeatin for yam micropropagation. Keywords: Cytokinin, auxin, morphogenesis, yam, Benin