Effect of growth regulators on multiple shoot induction from in vitro single node of Nagpur mandarin (Citrus reticulata Blanco)

Abstract

Nagpur mandarin is the most important commercially grown citrus cultivar in the central part of India. It holds a dominant position due to its suitability for consumption as fresh fruit, dessert fruit, and for its excellent juice with a pleasant flavor (Karwa, A., 2003). However, conventional propagation of Nagpur mandarin is limited due to its susceptibility to various diseases, genetic variability, labor-intensive processes, and risk of poor-quality fruit production. Therefore, the present study aimed to develop an in vitro regeneration protocol for the rapid multiplication of mandarin (C. reticulata). Single nodes from in vitro plantlets derived from seeds were used as explants. These explants were cultured on full-strength MS medium supplemented with various concentrations and combinations of plant growth regulators, including BAP, Kinetin, and GA₃ for shoot regeneration and half MS medium supplemented with various concentrations of IBA and NAA for root regeneration. The combination of BAP (0.5 mg/L) + GA₃ (1.0 mg/L) produced the highest number of shoots (4.8) at 90 days after shoot initiation. The greatest shoot length was recorded with GA₃ (1.5 mg/L), while the highest number of roots (3.20) was observed with NAA (2.5 mg/L), and the longest root (10.52 cm) was recorded with IBA (2.0 mg/L).