Comparative Evaluation of Auxins and Cytokinins on Callus Morphology and Biomass Accumulation

Plant growth regulators play a central role in determining callus induction, morphology, and growth performance in plant tissue culture systems. This study comparatively evaluated the effects of auxins and cytokinins on callus morphology and biomass accumulation under controlled in vitro conditions. Explants were cultured on Murashige and Skoog basal medium supplemented separately with graded concentrations of auxins or cytokinins, alongside a hormone-free control. Callus induction efficiency, qualitative morphological traits (color, texture, friability, and compactness), and quantitative biomass parameters (fresh and dry weight) were systematically assessed over defined incubation periods. The results demonstrated clear hormone-specific responses. Auxin treatments consistently promoted friable, lightly colored callus with significantly higher biomass accumulation, exhibiting a concentration-dependent response with optimal growth at moderate auxin levels. In contrast, cytokinin treatments produced compact to semi-compact callus with increased structural organization and lower biomass yield, reflecting a shift toward controlled proliferation and partial differentiation. Comparative analysis confirmed that auxins were more effective than cytokinins in maximizing callus proliferation and biomass production, while cytokinins primarily influenced callus structural characteristics. These findings highlight the importance of hormone selection and concentration optimization in callus-based culture systems and provide practical insights for improving micropropagation, secondary metabolite production, and genetic transformation protocols in plant biotechnology.