Evaluation of Selected Plant Growth Regulator Combinations for In Vitro Propagation of Orange-Fleshed Sweet Potato (Ipomoea batatas L.) cv. ‘Kulfo’: A Preliminary Comparative Screening Study

Abstract

Sweet potato (Ipomoea batatas L.) is a major food-security crop in developing countries, but its productivity is constrained by the accumulation of viral pathogens through repeated vegetative propagation. In vitro culture, combined with virus indexing, can provide clean clonal planting material. Still, micropropagation responses in sweet potato are genotype-dependent, and researchers have not compared combinations of plant growth regulators (PGRs) across the propagation stages of the Ethiopian orange-fleshed cultivar “Kulfo”. We compared a PGR-free control and two PGR combinations at each of three in vitro stages: shoot initiation (6-benzylaminopurine, BAP, with gibberellic acid, GA3), shoot multiplication (BAP with naphthalene acetic acid, NAA), and rooting (indole-3-butyric acid, IBA, with NAA), and we recorded survival during acclimatization. Nodal and apical explants were cultured on the Murashige and Skoog (MS) medium (completely randomized design; two temporal experiments). Among the treatments tested, 0.5 mg L−1 BAP + 0.1 mg L−1 GA3 gave the highest shoot regeneration (62% from nodal and 59% from apical explants); 1.0 mg L−1 BAP + 0.1 mg L−1 NAA gave the most shoots (7.2 per explant); and half-strength MS with 0.1 mg L−1 IBA + 0.1 mg L−1 NAA gave the most roots (13.3 per shoot at 30 days after inoculation). Plantlets derived from these treatments showed 98.0% survival during acclimatization. These results identify promising starting points for further work, which will require wider PGR gradients, single-PGR controls, additional cultivars, and virus and genetic-fidelity assessment of regenerants.