Micro- propagation and Mass production of Raktan (Lophopetalum wightianum Arn.), A Globally Threatened Evergreen Tree Species in Bangladesh.

Abstract Lophopetalum wightianum is a tropical or subtropical forests tree that has an aesthetic value as an ornamental plant, used for timber production and source of essential oils. Because of rapid agricultural and urban development, deforestation, climate change and indiscriminate collection, this important tree species have been included into red list of threatened species. The current study corroborates the earliest and first report on in-vitro micropropagation of L. wightianum aimed to develop a robust and reproducible protocol for mass propagation and conservation of this endangered plant species. Throughout the experiment, about 80% survivality of nodal segments, emergence and proliferation of microshoots and their subsequent multiplication was confirmed on MS medium fortified with BAP 2.0 mg/L and Kinetin 1.0 mg/L. In vitro rooting of L. wightianum shows recalcitrance and 40% rooting proficiency was achieved on 1/4 strength MS medium supplemented with low conc. of auxins (3.0 mg/L IBA and 0.5 mg/L IAA) for a prolong period of culture (03 months) where reduced concentration (2%) of sucrose showed a remarkable impact on root initiation. On the contrary, ex-vitro rooting trial yielded 55% of rooting competency with 72 hours of transient dipping of shoots on MS media supplemented with 50 mg/L IBA. Remarkably, 93% of in-vitro rooted plants survived during the acclimatization phase at open field condition. Plants survived from ex-vitro trial showed vivid growth and development after six months at field condition. The current findings provide greater insights for future research and conservation strategy of L. wightianum.