Augmenting in vitro Shoot Multiplication by Growth Regulators and Photoperiod in Vigna mungo L. (Hepper.)

An efficient in vitro protocol was developed for the mass multiplication of Vigna mungo vars. PU30 and PU31, an important legume crop through apical meristems and cotyledonary nodal explants. Both apical meristems and cotyledonary nodal explants were cultured on Murashige and Skoog (MS, 1962) medium fortified with 0.5 – 1.50 mg/L 6- benzyl aminopurine (BA) or Kinetin and 3 % (w/v) sucrose. The rate of multiplication was higher when the cultures were incubated under continuous light (24h) than the 16h photoperiod. The average number of multiple shoots per culture was enhanced from 2.43 to 5.46 in the case of var. PU30 and 3.12 to 5.82 in the case of var.PU31 within 4 weeks of culture under 24h photoperiod. The multiplication rate was enhanced till 5th subculture declined thereafter. Rooting was readily achieved upon transferring the shoots to half-strength MS basal semisolid medium supplemented with 0.1– 1.0 mg/L indole-3-butyric acid (IBA) and 2% (w/v) sucrose after 2 weeks of culture. The average number of roots per explants ranged from 3.12 to 5.76. About 80% of regenerated plantlets were hardened in the greenhouse and successfully established in the soil. There is no morphological variation among the regenerated plantlets. This protocol can be used for genetic transformation study for crop improvement of black gram.