Optimization of 6-Benzylaminopurine enhances micropropagation efficiency and subsequent rooting in Dendrobium orchid

Abstract

The Dendrobium orchid is a highly valued ornamental plant with significant commercial potential in the global floriculture market. However, conventional propagation methods are inefficient for large-scale production due to low seed germination rates, slow growth, and high susceptibility to diseases. In vitro micropropagation offers an effective alternative, enabling rapid clonal multiplication of genetically uniform and disease-free plantlets. This study aimed to determine the optimal concentration of 6-benzylaminopurine (BAP) for the mass propagation of Dendrobium orchids. Shoot tip explants were cultured on Murashige and Skoog (MS) medium supplemented with various concentrations of BAP in combination with 0.5 mg L-1 a-naphthaleneacetic acid (NAA). The results showed that shoot proliferation varied significantly with different BAP concentrations. The highest number of shoots/explant (5.4) was observed at 1.0 mg L-1 BAP + 0.5 mg L-1 NAA after 90 days of culture. Variations in BAP concentrations did not significantly influence shoot length, although the maximum shoot length (19.56 mm) was recorded in the medium containing 2.0 mg L-1 BAP + 0.5 mg L-1 NAA. The highest number of leaves (11.4) was also obtained from 1.0 mg L-1 BAP + 0.5 mg L-1 NAA. Root induction was significantly affected by previous BAP exposure, with the maximum number of roots (23.2) observed in plantlets derived from the same optimal BAP treatment. Root length remained statistically unchanged across treatments. Ex vitro acclimatization yielded a survival rate of 78.3% in a substrate mixture of coco-husk, brickbats, and charcoals (2:1:1). The optimized BAP concentration enhances shoot proliferation, ensuring a consistent supply of high-quality plantlets of Dendrobium orchid for the floriculture industry.