Optimization of Factors Influencing Shoot Multiplication During Micropropagation of Chlorophytum borivilianum Sant. et Fernand

Abstract

Various factors like propagule size, subculture strategy, gelling agents, liquid pulse treatment of BAP and vessel type were optimized for in vitro shoot multiplication in Chlorophytumborivilianum. It was observed that for optimum rate of shoot multiplication a propagule having five shoots each measuring 1.0 cm was necessary. Subculture strategy in which multiplying shoots after one subculture (42 days) were divided into clusters (each having five shoots) and subcultured on the fresh medium provided best rate of multiplication. Agar was found to be the best gelling agent. Lowering the concentration of agar to 0.4 % proved beneficial for shoot multiplication and elongation. Cheaper gelling agent like guar–gum alone or its combination with agar and Phytagel™ could not evoke response better than the agar used as control. In case of liquid phase pulse treatment of BAP, maximum number of shoots were obtained when the shoot clusters were pulse treated with 200 mg l−1 BAP followed by inoculation onto BAP-free medium and subsequently onto BAP containing medium. A 400 ml culture bottle stoppered with vented polypropylene cap proved to be the best for shoot growth and multiplication. More than 80 % callus-free rooting of shoots was recorded on ¾ MS medium supplemented with 2 mg l−1 IBA. Plants directly hardened under nursery shed conditions during monsoon season showed comparable or better growth and 90 % survival than the greenhouse hardened plants.