In vitro multiplication of Wthnia somnifera auxiliary buds for mass propagation

Wthnia somnifera of family Solanaceae commonly known as Amukkara or Ashwaganda is an important medicinal perennial herb with long tapering roots. The roots are widely used in ayurvedic medicine and prescribed for hiccup, female disorders, cough and rheumatism. Wild and cultivated forms are available and cultivated plants differ in morphological and therapeutical action from wild ones. The annual requirement of 42347 kg is imported from India spending Rs. 2, 840, 449 (IUCN , 2005). Development of a method for in vitro mass production of this valuable species would substantially reduce the import cost and generate employment opportunities. This study was conducted to develop an in vitro protocol for mass production of W. somnifera.

In vitro grown seedlings of W. somnifera were used to excise single nodal cuttings and cultured on MS (Murashige & Skoog, 1962) medium. The effect of NAA (0, 0.1, 0.2 mg/l) in combination with BAP (0.5, 1.0, 1.5 mg/l) on shoot proliferation was tested in solid and liquid MS media containing two levels of sucrose (3% and 4%). Proliferation (number of plantlets produced) was observed at weekly intervals.

Highest shoot proliferation rate (1: 20) was observed in solid MS medium containing 3% sucrose and 1.5mg/l BAP after two months. In solid MS medium with 4% sucrose and 1.0 mg/l BAP 1: 10 shoot proliferation rate was observed after two months. During the same time period 1:15 shoot proliferation rate was observed in solid MS medium with 3% sucrose, 0.5 mg/l BAP and 0.2 mg/l NAA, where 1: 12 proliferation rate was observed when BAP concentration increased up to 1.0 mg/l. Solid MS media both with 3% and 4% sucrose levels and 0.5 mg/l BAP showed some proliferated shoots while other solid cultures were not proliferated. However cultures containing NAA in addition to BAP enhance rooting of proliferated shoots before transferring the separated shoots to rooting media. The explants in liquid MS medium with 4% sucrose and 1.0 mg/l BAP, proliferation initiated in one week and gave 1:40 shoot multiplication rate after two months. Rest of the liquid cultures with different BAP and NAA combinations were not proliferated within the same time duration.

Finally it can be concluded that highest shoot proliferation of W. somnifera through single nodal cuttings can be obtained on liquid MS medium with 4% sucrose and 1.0 mg/l BAP.

P S Warakagoda, D L C Kumari and S Subasinghe
Department of Crop Science, Faculty of Agriculture, University of Ruhuna, Sri Lanka

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