Integrated Morphological, Biochemical, and Regrowth Assessment of Ghanaian Yam Accessions During Medium-Term In Vitro Conservation

Conventional propagation of yam (Dioscorea spp.) is constrained by low multiplication rates, pathogen accumulation, and vulnerability of field-maintained germplasm to biotic and abiotic losses. However, most studies emphasize survival, whereas fewer evaluate accession-specific growth performance alongside water-extractable phenolic content and antioxidant responses under the same conservation conditions. This study integrated morphological, biochemical, and post-conservation regrowth assessments to evaluate eight Ghanaian yam accessions maintained for 24 weeks on hormone-free complete Murashige and Skoog medium. The experiment followed a completely randomized design with three biological replications. All accessions maintained 100% survival without contamination throughout conservation, although substantial accession-dependent differences occurred in vegetative performance. At week 24, UWR produced 5.5 shoots/plant, 14 leaves/plant, and reached 8.5 cm height, while NKURAKAU produced 4.5 shoots plant−1 and reached 8.2 cm. In contrast, SO showed weaker growth, producing 2.8 shoots plant−1, 6 leaves plant−1, and 4.5 cm height. During four weeks of post-conservation recovery, NKURAKAU exhibited the strongest regrowth, producing 1.8 shoots plant−1, 4.2 leaves plant−1, and 5.0 cm high plantlets. Biochemical responses were also accession-specific. AMO exhibited the highest water-extractable TPC after 24 weeks of conservation (4.1 mg GAE/100 g dry weight), whereas UWR showed the lowest response (1.7 mg GAE/100 g dry weight). Conversely, SO and NKURAKAU exhibited comparatively strong DPPH radical-scavenging activity despite lower phenolic contents. No statistically detectable linear association between endpoint TPC and DPPH radical-scavenging activity was observed among the eight accessions (r = −0.24, p > 0.05). Exploratory hierarchical clustering of biochemical trait distinguished AMO as higher-TPC phenotype and SO/NKURAKAU as higher-DPPH phenotype. Overall, combining morphological traits, biochemical indicators, and post-conservation regrowth provides a more informative basis for accession-specific germplasm management than survival alone. NKURAKAU and UWR showed the most balanced performance, while AMO was notable for shoot multiplication and higher TPC.