SELECTING LOW TEMPERATURE-TOLERANT ORGANOGENIC CALLI AND PLANT REGENERATION OF Melia azedarach L.

Abstract

This work was developed from 1992 to 1994 at the Vegetative Propagation Experimental Centre, La Plata City, Argentina. Our aim was to get Melia azedarach plants tolerant to low temperatures through the in vitro selection of organogenic calli. This species is important in forest industry and as a source of secondary metabolites with insecticide and medicinal properties. Its sensivity to late frosts, originated in its low thermal threshhold for shooting, makes difficult its extensive culture. The general tissue culture in vitro methodology was used applying selection pressure to abiotic stress from organogenic calli. An efficient method to obtain whole plants through indirect organogenesis was developed. About 45 % of calli under low temperature survived with a regeneration rate of 1 to 5 shoots every 250 mg of callus. The whole plants presented an 85 % survival under greenhouse conditions. Giberellic acid has proved to have great influence in meristemoid formation in calli of this tree. In conclusion, the selection of plants tolerant to low temperature through the in vitro tissue culture is a promising alternative to complement improvement programs in forest species.