An Efficient Protocol for Direct in vitro Regeneration in ‘Daisy’ and ‘W. Murcott’: Commercially Important Mandarins

The goal of the current study was to develop a standardized protocol for efficient in vitro regeneration of citrus cultivars ‘Daisy’ and ‘W. Murcott’ mandarin. Treatment with 0.1% mercuric chloride (HgCl₂ for 5 min) and 0.5% Bavistin (10 min) effectively induced seed germination in ‘Daisy’ at 87.20%. Intermodal explants showed a high establishment rate of 98.80% in both ‘Dasiy’ and ‘W. Murcott’. Maximum shoot regeneration of 98.20% was recorded on MS fortified with 0.5 mgL⁻¹ BAP + 0.5 mgL⁻¹ Kinetin using nodal segments, followed by leaf explants (88.80%) on MS enriched with 2.0 mgL⁻¹ BAP. Highest shoot proliferation (2.6 shoots per explant) with mean shoot length of 2.3 cm was observed on MS containing BAP (2.5 mgL⁻¹) in ‘Daisy’ mandarin whereas, highest shoot length (3.64 cm) was recorded on MS medium supplemented with 2.5 mgL⁻¹ BAP and 0.5 mgL⁻¹ GA₃. However, in ‘W. Murcott’, highest shoot multiplication (2.60 shoots per explant) with 1.9 cm mean shoot length was recorded on MS + BAP (3.0 mgL⁻¹). Whereas, maximum mean shoot length of 3.50 cm was observed on MS enriched with BAP (2.0 mgL⁻¹) and GA₃ (0.5 mgL⁻¹). Highest in vitro rooting (70.60%) with 2.3 average root number was observed on ½ MS supplemented with IBA (1.0 mgL⁻¹) in ‘Daisy’ mandarin, in comparison to 68.40% rooting with 2.1 average number of roots in ‘W. Murcott’ on ½ MS + IBA (0.5 mgL⁻¹). In vitro rooted plants when hardened showed 80.00% survival in ‘Daisy’ and 72.33% survival in ‘W. Murcott’ in potting mixture composed of cocopeat + vermiculite + perlite (2:1:1) after one month of hardening with no morphological variations.