Clonal propagation of selected plus trees of Indian rosewood (Dalbergia latifolia Roxb) through tissue culture

Abstract

An investigation was carried out at College of Forestry, Vellanikkara during 1993 – 1995 on micropropagation of selected plus trees of Indian rosewood (Dalbergia latifolia Roxb.) through tissue culture. Nodal or intermodal explants from the three selected plus trees as well as root suckers of one among them were used for the study. Explants from young (eight to ten year old) rosewood trees were also taken, in order to know the difference in culture response if any, between adult and juvenile plant materials. Prophylactic spraying with the mixture of Bavistin and Indofil M-45 given to young trees as well as root suckers or immersing the explants from the plus trees for one hour in the same fungicidal mixture coupled with surface sterilization of explants with 0.1 per cent mercuric chloride for 12 minutes could control culture contamination very effectively. Phenol problem was nil for young trees whereas treatments with ascorbic acid, citric acid and polyvinylpyrrolidone were essential to check browning of the cultures of explants from plus trees as well as root suckers. Woody plant medium supplemented with 1.0 mg 1-1 kinetin along with 0.1 mg 1-1 IAA was the best combination for young trees whereas addition of 2.0 mg 1-1 BA to MS medium proved to be better than the others, in case of plus trees. While in vitro propagation using explants from young trees of rosewood could be achieved and plantlets could be regenerated with cent per cent repeatability, micropropagation of the selected plus trees of rosewood faced with many obstacles. Though bud break and shoot morphogenesis was noticed in some of the media combinations tried with BA, kinetin and 2-ip alone or along with IAA or NAA, none of them could improve the problem of lack of multiple shoot formation or leaf expansion. Adenine sulphate, casein hydrolysate, cycocel, phloroglucinol, coconut water and activated charcoal were found to have no significant beneficial effect on culture of plus trees of rosewood. However, L-glutamine added to the medium at higher concentrations was found preventing precocious drop of leaf initials. In vitro rooting was achieved by resorting to a pulse treatment of the shoots with IBA (1000 mg 1-1) and culturing them in half strength MS medium containing 1.0 per cent activated charcoal and hardening and planting out of the plantlets was also carried out for young trees. Rooting trial was a failure with plus trees as well as root suckers. Callus cultures were successfully initiated from intenodal segments from root suckers. Shoot regeneration was noticed in 14.3 per cent of these cultures. However, leaf expansion or multiple shoot formation could not be obtained. The study clearly portrays the difference in culture response between juvenile and adult explants from Dalbergia latifolia.