Effect of Plant Growth Regulators on in Vitro Propagation of Yam Landraces (Dioscorea Species) Using Nodal Segments

Abstract

Conventional propagation of yam (Dioscorea spp.) is limited due to low propagation rates. However, In vitro propagation is the best alternative to overcome such limitations of conventional propagation. For both shoot multiplication and rooting experiments, nodal segments were cultured on hormone free MS medium with combination of 30 g/l sucrose and 8 g/l agar. For shoot multiplication the initiated shoots of both landraces were cultured on MS media supplemented with 0.0, 0.5, 1.0, 2.0 and 2.5 mg/l benzyl amino purine (BAP). For root induction, shoot lets were cultured on MS media supplemented with 0.0, 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0 mg/l indol -3-butyric acid (IBA). Finally, for acclimatization, in vitro multiplied plantlets were transferred to greenhouse for hardening off. The results showed that the interaction effects of both landraces with BAP and IBA concentrations was significantly influenced in vitro yam shoot multiplication and rooting respectively. MS media fortified with 1.5 mg/l BAP gave the highest shoot number (6.79 ± 0.09) with a shoot length of 7.47± 0.47 cm in 75/02. The maximum shoot number (7.23 ± 0.21) with a maximum shoot length7.68 ± 0.24cm was obtained on MS media supplemented with 1.5 mg/l BAP for 6/02. On rooting, MS media with 1 mg/l and 0.5 mg/l IBA gave maximum rooting percentage (54.33% and 68%) for75/02 and 6/02 landraces, respectively. The maximum root number (10.03 ± 0.49) and root length10.76± 0.16 cm were recorded on MS media with 1.5 mg/l IBA for 75/02. The maximum root number (10.58 ± 0.26) with highest root length (10.42 ± 0.32) cm was obtained on MS media with 2.00 and 1.00 mg/l IBA respectively for landrace 6/02. In vitro raised plantlets were acclimatized and recorded 86% and 90% of survival rate in75/02 and 6/02, respectively, on soil medium with combination ratio of 1:2:1 top soil, sand soil and compost, respectively.

Keywords: BAP, IBA, Micro-propagation, in vitro culture Nodes, Dioscorea species Yam