Diversity analysis reveals significant variations in Dioscorea bulbifera L. collected from Kerala, India, enabled identification of superior germplasm

Abstract

Dioscorea bulbifera L., commonly known as aerial yam or air potato, belongs to the family Dioscoreaceae. The plant has both medicinal and edible value. The aerial tuber (bulbils) and the underground tuber serve as good sources of staple food, rich in minerals and metabolites. Despite its potential to be elevated as a tuber crop in the tropics, it is surprisingly listed as an underutilised tuber in various parts of the world, particularly in the southernmost state of Kerala, India. Therefore, the present study aims to evaluate the diversity of D. bulbifera accessions collected from different agroecological zones of Kerala, India, through morphological trait markers. For the evaluation, 33 accessions of D. bulbifera (Db) were collected by visiting 105 sites and subjected to analysis by using 39 descriptors developed by the International Plant Genetic Resources Institute/ International Institute of Tropical Agriculture specific to yam crops. Quantitative trait evaluation based on tuber characters such as number of aerial tubers (7.60–23.60 tuber/plant), aerial tuber weight (18–392 g/plant), bulbil yield (0.23–9.23 kg/plant), aerial tuber diameter (1–10.18 cm), and aerial tuber length (0.78–9.58 cm) varied among the accessions. The diversity estimation based on various components, including Genotypic variance (σ2g), environmental variance (σ2e), phenotypic variance (σ2p), phenotypic coefficient of variation (PCV) and genotypic coefficient of variation (GCV), broad sense heritability (H2B) and genetic advance (GA), were evaluated. Among the 33 accessions, the PCV was higher than the GCV, indicating that variation among the accessions is not solely due to genetic traits but also to environmental conditions. Accessions with heritability above 95% for traits with moderate genetic advance as a selection tool for the superior germplasm (Db18) selection within the population. Correlation analysis showed a significant positive correlation, especially in tuber characters. Scatter plot evaluation followed by dendrogram construction distinguishes the entire 33 accessions of D. bulbifera by divergent characters related to leaf and tuber traits and allocates the entire accessions irrespective of their geographical location of collections. The overall evaluation of the entire 33 accessions of D. bulbifera by morphological traits reveals significant variations among the accessions and illustrates the selection of superior germplasm based on the number of aerial tubers and also the aerial tuber yield per plant.