The effect of plant growth regulators and sucrose on the micropropagation and microtuberization of Dioscorea nipponica Makino

The effects of sucrose, plant growth regulators, MS (Murashige and Skoog), and 1/2MS salt media formulations were investigated for the development of shoot cultures, microtuber induction, and plantlet regeneration in Dioscorea nipponica. The cytokinin N-benzyladenine (BA) in the range of 0.5-2.0 mg/l showed strong enhancing effects on microtuber induction only when used in conjunction with the auxin alpha-naphthalene acetic acid (NAA), with the effect that NAA increased from 0.5 to 2.0 mg/l. Murashige and Skoog salt media supplemented with sucrose at 3% (w/v) gave the highest frequencies of shoot induction (86%) when BA was present at 2.0 mg/l and NAA at 1.0 mg/l. Sucrose at 7% (w/v) was the single most significant medium constituent for microtuber growth. The heaviest microtubers were formed on media containing 1.0 mg/l BA and 2.0 mg/l (0.073 g), especially with 7% sucrose (3.46 g). With media containing 1/2MS, 2% sucrose, and 0.1% (w/v) activated charcoal, the percentage of rooting was maximal when supplemented with 1.0 mg/l BA and 0.5 mg/l NAA for the in vitro produced shoots (95%) and BA and NAA both at 0.5 mg/l for the microtubers (100%). When removed from culture flasks and transferred into sterilized soil in a greenhouse, most of the hardened plantlets survived (over 91% after 1 week), and they were suitable for field planting after 1 month. © 2007 Springer Science+Business Media, Inc.