Effective preconditioning methods for in vitro propagation of Uapaca kirkiana Müell Arg. tree species

Abstract

The objective of the study was to determine efficient preconditioning methods for in vitro multiplication of Uapaca kirkiana plant materials from mature stock plants. The efficacy of sodium hypochlorite
(NaOCl), calcium hypochlorite {Ca(OCl2)2} or mercuric chloride (HgCl2) as surface sterilant was evaluated in decontaminating explants excised from grafted and field-collected U. kirkiana trees.
Different Murashige and Skoog (MS) medium supplements were evaluated for shoot multiplication and root regeneration. Results indicated that preconditioning grafted U. kirkiana trees before excising
explants and decontaminating explants in 0.1% w/v HgCl2 were effective methods in establishing aseptic cultures (80%). Lateral shoots (new shoots) responded positively to shoot multiplication on ¾
strength MS medium supplemented with a combination of 0.1 mg/L benzylaminopurine, 0.04 mg/L naphthaleneacetic acid and 0.3 mg/L casein hydrolysate. High concentrations of thidiazuron (>0.1 mg/L)
suppressed bud break. Rooting (36%) was achieved with ½ MS medium supplemented with 2.5 mg/L indole-3-butyric acid. Plantlets were successfully hardened off. In vitro multiplication of mature U.
kirkiana plant materials was achieved using lateral shoots excised from grafted U. kirkiana trees after preconditioning with fungicides.