Establishment of In vitro Regeneration Protocol of Aegle marmelos (L.): A Sacred Medicinal Tree

Bael (Aegle marmelos L.) is an important medicinal tree and sacred tree species of the Hindu religion. This study aimed to develop an efficient in vitro regeneration protocol for Bael, to overcome challenges in large-scale propagation due to low seed germination. For the regeneration study, the different explants such as the nodal segments and shoot tips were used for the proliferation of the explant with MS medium, however, only the nodal segment showed positive results. To avoid the browning of the media the explants were kept in distilled water for 60 minutes and then sterilized. The maximum survival of explants (93.33%) and less contamination percentage (6.67%) was observed when explants were washed and treated with 0.1% Tween-20 concentration for 15 minutes + 0.1% bavistin and 0.05% streptocycline treatment for 25 minutes and finally 70% ethanol treatment for 30 seconds. Different hormonal combinations viz. BAP alone, BAP + IAA, and Kinetin + IAA were used to initiate shooting. Among all eighteen treatments, the BAP 2.5 mg/l showed a maximum number of shoots per explant (8.33 ± 2.88), the highest shoot initiation (93.33%), and the earliest initiation (30 ± 5.25 days). For shoot multiplication 2.5 mg/l BAP + 0.5 mg/l NAA showed maximum shoots per explant (28.00 ± 5.08) and fastest shoot proliferation. The regenerated multiple shoots were separated from each other and transferred to half MS media with IBA of different concentrations for rooting. Among the six different treatments only two treatments viz. ½ MS media + 1.0 mg/l IBA and ½ MS media + 1.5 mg/l IBA recorded best root length. For primary hardening the rooted plants were planted in vermicompost: sand: soil at 1:1:2 proportion and then after one and half months survived plants were again transferred to soil: organic manure (2:1) for secondary hardening.