Variability in dry matter content and yield-related traits in sweetpotato (Ipomoea batatas [L.] Lam.)
Abstract
Understanding genetic variability is fundamental to sweetpotato (Ipomoea batatas [L.] Lam.) improvement. This study evaluated 44 genotypes across two locations in Nigeria, Ejigbo and Ilesa, over two growing seasons (2023-2024) to estimate genetic variability, heritability, genetic advance, and associations among yield-related traits, morphological descriptors, and dry matter content. The experiment used a randomised complete block design with three replications. A combined analysis of variance revealed highly significant genotypic effects (p < 0.01) for all traits, with significant genotype × environment interactions for most yield-related traits. The phenotypic coefficient of variation exceeded the genotypic coefficient of variation for all traits, although the differences were small. Broad-sense heritability ranged from 74 % for stand count to 100 % for pigmentation traits and dry matter content, while genetic advance ranged from 14.09 % for fresh shoot yield to 178.90 % for petiole colour. Genotypic correlation analysis showed significant positive associations between mature leaf length and both fresh shoot yield (r = 0.38) and fresh root yield (r = 0.32), whereas petiole colour exhibited the strongest negative correlation with dry matter content (r = −0.40). Path coefficient analysis identified petiole colour as having the largest negative direct effect (−0.54) on dry matter content, whereas mature leaf colour and vine length exerted the largest positive direct effects (0.13 each). The residual effect (0.83) indicates that additional factors influence dry matter accumulation. These findings demonstrate substantial genetic variability and high heritability for most traits, suggesting promising prospects for genetic improvement through selection. However, significant genotype × environment interactions and trade-offs between pigmentation and dry matter content necessitate multi-environment testing and careful breeding programme design.