Standardization of an efficient protocol for in vitro mass multiplication of Hybrid Tea rose cv. Raktima

An efficient protocol for in vitro micropropagation of hybrid tea rose cv. Raktima was standardised using axillary bud explant. Before inoculation, explants were treated with different concentrations of fungicides and bactericides. Out of different pre-treatments tried, the highest explant survival (73.83%), bud sprouting (69.28%) with minimum microbial contamination (17.16%) were obtained with carbendazim (0.2%) + dithane M-45 (0.2%) + 8-HQC (200 mg/l) for 3 h treatment on a horizontal shaker (120 rpm). The effect of different combinations of BAP (2.5, 3.0 and 3.5 mg/l), NAA (0.1 and 0.2 mg/l), and GA₃ (0.3 and 0.5 mg/l) on culture establishment and shoot proliferation was studied. Murashige and Skoog (1962) medium supplemented with BAP (3.0 mg/l) + NAA (0.1 mg/l) + GA₃ (0.5 mg/l) was found most effective for culture establishment with highest explant survival (94.83%) and bud sprouting (91.90%) and on shoot proliferation with highest number of micro-shoots per explant (9.50). Better rooting on micro-shoots was induced on half-strength MS basal medium supplemented with NAA (0.5 mg/l) + IBA (0.5 mg/l) with highest rooting (94.13%). The regenerated plantlets were hardened in glass jars filled with vermiculite + agropeat (1:2) moistened with one quarter-strength MS salts (macro and micro) and covered with polypropyline lids resulting in maximum survival (91.86%). After hardening, plants were successfully transferred to the glasshouse with good survival.