Induction, Growth Kinetics and Morpho-histological Characterization of Neem Callus

Azadirachta indica A. Juss, popularly known as neem, is a species native to India, belonging to family Meliaceae, considered the most important plant species with insecticidal action. The aim of this study was to evaluate the influence of growth regulators on induction and growth of neem callus and to observe their viability for embryogenesis through morpho-histological characteristics. In vitro germinated plants were used for excision of nodal explants. These segments were inoculated in Murashige and Skoog culture medium containing 1.0 mg/l 2,4-D (2,4-dichlorophenoxyacetic) combined with BAP (6-benzylaminopurine) at the following concentrations- 0.0, 0.5, 1.0 and 2.0 mg/l (T1, T2, T3 and T4 respectively), for callus induction. At 0 (mass of nodal segments without callus), 20, 40 and 60 days of culture, the percentage of callus formation was observed and the callus weight was measured for each treatment and at the end of the 60 days, consistency, color, and cell histology were evaluated. There was callus formation in all treatments tested. The highest induction of Azadirachta indica A. Juss callus is observed in the presence of 1.0 mg/l 2,4-D + 2.0 mg/l BAP, with callus showing light brown color, friable consistency and rounded cells with intense cell division, typical of cells with potential embryogenic capacity.