Micropropagation of Polianthes tuberosa L. Through Direct Organogenesis

Polianthes tuberosa L. is one of the most important ornamental bulbous plants in tropical and subtropical regions that is cultivating in some regions of Iran. Due to the transmission of fungal and bacterial diseases, propagation by bulbs is not affordable. Tissue culture is a good way to produce uniform and disease-free seedling. Therefore, in vitro cultivation of tuberose is a suitable solution to commercial reproduction.

To investigate the best method of micropropagation of Polianthes tuberosa, this study was conducted in three experiments (proliferation, root formation and adaptation). The explants used in this study were lateral buds. Ethyl alcohol (70%) and dilute laundry bleach (5.25% active chlorine), benomyl fungicide and dishwashing liquid were used to eliminate surface contamination of the explants. In the first experiment, the effect of different plant growth regulators and MS medium (MS, ½ MS, ¼ MS) on shoot formation of lateral bud was investigated. Lateral bud explants were cultured in MS medium with various plant growth regulators including KIN (0.25, 0.5, 0.1, 0.2 and 0.4 mg / L), BAP (0.25 (0.5, 0.1 and 2.0 mg / l) and then the length and number of shoots were evaluated. After forming shoots in the propagation medium, they were transferred to a new environment to form roots.The root formation experiment included tree levels of  NAA concentrations, (0.5, 0.75 and 1 mg/L) in combination with 0.2 mg/L IBA and control (without growth regulator). Adaptation experiment with 5 Substrate of bed including Peat Moss, Cocopeat, Sand, Peat Moss with Cocopeat (1: 1) and Sand with Cocopeat and Peat Moss (1: 1: 1) was conducted.

The results showed that there was a significant difference between various types of plant growth regulators (PGR) and MS culture media at different concentrations and no branch was produced without the use of PGR. In shoot prolifferation experiment, the maximum number of shoots (4.8) was obtained from lateral bud explants in MS medium with 0.25 mg / l BAP in combination with 0.25 mg / l KIN. The highest length of lateral shoot shoots (3.75 cm) was observed in MS medium with 0.25 mg / l KIN in combination with 0.25 mg / l BAP.The results of root formation experiment showed that the highest number of roots was observed in MS medium containing 0.5 mg / l NAA and 0.2 mg / l IBA and the lowest number of roots in control (without plant growth regulator). Treatment of 0.5 mg / l NAA with 0.2 mg / l IBA had the highest root length (1.22 cm). The lowest root length was also observed in the control (without plant growth regulator). In the adaptation test, no significant difference was observed between treatments in survival rate.

The results of this study showed that the shoot organogenesis is controlled by the cytokinin with MS medium in different concentrations. It should be mentioned that cytokinin had an important role in the synthesis of RNA, stimulation of the production of protein and the activity of some enzymes. Also, the results showed that the use of cytokinin alone has a beneficial effect on shoot organogenesis.