Griselida Rojas-Campos

Physalis peruviana L. is an Andean crop of high nutritional and commercial value; however, the limited availability of uniform planting material restricts its large-scale propagation. Indole-3-butyric acid (IBA) is widely used to promote adventitious rooting, although its concentration and application methods influence the response observed throughout the different stages of root development. This study evaluated how IBA concentration and explant origin influenced rooting-related traits and early vegetative growth of in vitro-regenerated P. peruviana shoots during a 30-day ex vitro acclimatization phase. The evaluated variables included rooting percentage, root number, longest root length, root fresh and dry mass, shoot length, leaf and node number, stem diameter, shoot fresh and dry mass, leaf area, and photosynthetic pigment contents. The experiment followed a completely randomized design with a 2 × 4 factorial arrangement consisting of two explant origins (cotyledon and hypocotyl) and four IBA concentrations (0, 400, 800, and 1600 mg L⁻¹), with five biological replicates per treatment combination. All shoots formed at least one visible root, resulting in 100% rooting across all treatment combinations. IBA concentration significantly affected root fresh and dry mass and several shoot-growth traits, whereas root number and longest root length were not significantly affected. Among the concentrations tested, 800 mg L⁻¹ produced the highest root biomass and favorable responses in selected shoot-growth traits, whereas 1600 mg L⁻¹ was associated with lower values for some growth variables. Hypocotyl-derived shoots had more leaves and nodes, greater stem diameter, and higher shoot dry mass than cotyledon-derived shoots. These results indicate a concentration- and trait-dependent response to IBA and identify 800 mg L⁻¹ as the most favorable concentration among those tested for increasing root biomass and selected shoot-growth traits under the evaluated acclimatization conditions.