Micropropagation of Tohiti rattan ( <i>Calamus inops</i> Becc. ex Heyne) through secondary somatic embryogenesis for <i>ex-situ</i> conservation

This study presents the first successful report on the propagation of Tohiti rattan (Calamus inops Becc. ex Heyne), a species of high economic value, through the development of secondary somatic embryogenesis (SSE). The research primarily investigated the effect of 6-benzyl-adenine (BA) on SSE induction and subsequent plantlet development. Primary somatic embryos were utilized as explants, and the study was conducted over four critical stages: induction of globular-stage SSE, maturation of SSE, rooting, and acclimatization of plantlets. BA treatments, ranging from 3.29 µM to 17.76 µM, were applied during the SSE induction stage, with 13.32 µM BA evoked the highest induction rates. After 13 weeks, an average of 8.6 globular-stage embryos per treatment was observed. The maturation stage, extending to 25 weeks without subculturing, resulted in an average of 5.0 scutellar-stage embryos and 3.0 coleoptilar-stage embryos under the same BA concentration. During the rooting phase, 1.476 µM indole-3-butyric acid (IBA) produced the highest number of roots, with an average of 5.33 roots per plantlet at 13 weeks. The acclimatization stage, using a 1:1 soil and sand medium, led to vigorous plantlet growth with green leaves. The highest success rate for plantlet acclimatization was 66.6%, achieved after 20 weeks with the 1.476 µM IBA treatment. This research provides critical insights into the propagation and ex-situ conservation of Tohiti rattan, offering a robust framework for enhancing both commercial production and the preservation of this valuable species.