Propagation of Rathamilla (Lumnitzera littoreae) a rare mangrove plant

Abstract

Diversity of flora in Sri Lanka is being subjected to continuous depletion due to over exploitation from natural habitats and lack of systematic propagation techniques, especially for rare species of plants. Rathamilla {Lumnitzera littoreae) is such rare mangrove tree species found in Sri Lanka. Only few trees currently exist in the southern region in “Maduganga” mangrove ecosystem, “Erawanadoowa” in Galle district. Therefore the conservation and multiplication of “Rathamilla” is timely importance. As propagation techniques, seed germination, propagation by cuttings, application of layering methods were applied at the faculty of Agriculture, University of Ruhuna and at the Madugaga site. Fully matured seeds were used for germination studies. Following treatments were applied on over night soaked seeds. Soaked seeds were divided in to two sets. One set of seeds was directly sown in moist sand. The other seed set, pericarp was removed and following treatments were applied, directly sown in moist sand, treated with 100% sulfuric acid for 15 seconds, treated with 50% sulfuric for 15 seconds, treated with sixty Centigrade hot water for 01 minuet. In all the seed treatments, there was no sign of germination over a period of one month, although seeds remain viable when used for germination. In vegetative propagation double nodal cuttings with leaves were used. Induction of root formation of all three cutting types (hardwood, semi-hardwood, softwood type) was tried with two root hormones, NAA and IBA in sand and coir dust 1:1 medium. Callus formation was observed in 6-8 weeks after planting. It was found that callus formation is better in soft wood cuttings with high concentration of NAA. Identified mother tree was used for layering. Randomly selected semi- hardwood type and hardwood type branches were selected and commercial hormone mixture (secto) was applied. Four weeks after layering, there was a sign of callus formation with “secto” and 8 weeks after layering, rooted branches were separated from mother plant and observation were recorded. The number of roots/layerage and the root lengths were much higher compared to control (without applying hormone).