Selection of Optimal 6-Benzylaminopurine (BAP) and 1-Naphthaleneacetic Acid (NAA) Combination for in vitro Propagation of ‘Solanum tuberosum L. cv. Cardinal’ Under Nepalese Laboratory Conditions

Aim: To evaluate the effects of different concentrations of 6-benzylaminopurine (BAP) and 1-naphthaleneacetic acid (NAA) on in vitro propagation of Solanum tuberosum L. cv. ‘Cardinal’ and to identify an optimal hormonal combination for rapid shoot and node proliferation for pre-basic seed production. Study Design: A laboratory-based in vitro experiment arranged in a Completely Randomized Design (CRD) with multiple BAP–NAA treatment combinations, including a hormone-free control. Place and Duration of Study: Central Laboratory and Horticulture Department Laboratory, Institute of Agriculture and Animal Science (IAAS), Paklihawa Campus, Bhairahawa, Nepal. Each culture phase was evaluated for 24 days. Methodology: Apical meristems excised from sprouted tubers of the potato cv. ‘Cardinal’ was cultured on full-strength Murashige and Skoog (MS) medium. Shoot initiation was carried out on MS medium supplemented with 0.5 mg/L BAP + 0.01 mg/L NAA. For shoot proliferation and rooting, explants were subcultured onto MS media containing different BAP and NAA concentrations. Numbers of leaves, nodes, and roots were recorded up to day 24. Data were analyzed using one-way ANOVA, and means were separated using Duncan’s Multiple Range Test at p = 0.05. Results: Shoot initiation was achieved on MS medium with 0.5 mg/L BAP + 0.01 mg/L NAA. The highest shoot and node proliferation occurred on MS medium supplemented with 1.5 mg/L BAP + 0.1 mg/L NAA, producing 8.92 ± 0.52 leaves and 2.88 ± 0.25 nodes per explant on day 24. Maximum rooting (4.83 ± 0.19 roots per explant) was obtained with 0.25 mg/L BAP + 0.3 mg/L NAA. Conclusion: Although different hormonal combinations optimized individual growth traits, 1.5 mg/L BAP + 0.1 mg/L NAA was identified as the most effective medium for rapid shoot and node proliferation. This genotype-specific protocol for the ‘Cardinal’ variety is newly documented under Nepalese laboratory conditions and is suitable for limited-resource laboratories.