In Vitro Rooting of Dendrobium nobile Orchid: Multiple Responses to Auxin Combinations

Orchids are the most adorable in flowering plants, cultivated as the cut flower and potted plants throughout the world at different occasions. For their commercial exploitation and conservation of endangered species, micropropagation has been extensively practiced, which may be affected by several factors at each step. In vitro rooting is the most important stage that may ultimately be responsible for successful transplantation of the plantlets. Auxins play a vital role for in vitro rooting. In present study NAA and IBA treatments to in vitro developed microshoots produced multiple responses. Findings show that NAA concentrations alone were better and vigorous than IBA alone in terms of number, length and root thickness. Increasing the NAA concentration from 0.1 to 3.0 mg l-1 proved progressive. The highest significant value in root development was obtained with NAA at 3.0 mg l-1. In case of IBA alone, the root number was increased by increasing its concentration up to 1.0 mg l-1 but, root number decreased when the concentration of IBA was increased to 3. 0 mg l-1. However, the combined effect of both the PGRs over root formation indicated a considerable decline in root formation as well as callus formation at microshoot bases