Optimizing Silver Nanoparticle Concentrations to Improve the In Vitro Regeneration and Growth of Phalaenopsis Orchids

초록

Phalaenopsis orchids are economically important ornamental crops; however, their commercial micro-propagation is often limited by poor rooting efficiency and inconsistent growth. In this study, we investigated the effects of silver nanoparticles (Ag-NPs) on the in vitro regeneration and growth of Phalaenopsis cultivar 611B to determine the optimal concentration of Ag-NPs for improved micropropagation outcomes. Shoot tip explants (2-3 mm)-derived from protocorm-like bodies were cultured on a regeneration medium containing Hyponex (20:20:20 and 6.5:6.5:19), 18 g/L sugar, 2 g/L peptone, 0.8 g/L activated charcoal, 12.5 g/L potato extract, 50 mL/L apple juice, and 10 mg/L 6-benzylaminopurine (6-BA), with varying concentrations of Ag-NPs (0, 0.5, 1.0, 2.0, and 2.5 mg/L). After 10-12 weeks, shoot and root formation, plant height, fresh weight, leaf number, and chlorophyll contents were evaluated. At 1.0 mg/L Ag-NPs, shoot regeneration (5.4 vs. 2.9 shoots per explant), root induction (2.1 vs. 1.4 roots per explant), and shoot formation frequency (100% vs. 55%) were significantly higher than the control (0 mg/L). Fresh weight (592.4 mg) and leaf number (9.7) also showed notable increases at this concentration. Although chlorophyll a and b levels peaked at 2.0 mg/L, the difference from 1.0 mg/L was not statistically significant. These results suggest that 1.0 mg/L Ag-NPs is the optimal concentration for enhancing shoot and root development and improving overall plantlet quality in Phalaenopsis. The findings highlight the potential of nanomaterials to improve the efficiency of orchid tissue culture systems.

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