Genetic Diversity Analysis by D2 Clustering for Mineral Nutrient Composition of Watermelon Genotypes (Citrullus sp.)

Abstract

Background: Watermelon is an important cucurbit with rich genetic diversity. A great proportion of this diversity remains largely unexploited in terms of mineral nutrient composition. Methods: The contents of eight different mineral nutrients were determined in eighty diverse genotypes. D2 statistics and principal component analysis were used to cluster genotypes and understand the underlying variations in mineral nutrient compositions of watermelon genotypes. Result: Large variations in the content of many mineral contents such as Na, K and Zn were recorded. D2 analysis placed the eighty watermelon genotypes into 8 distinct clusters. Cluster I comprised of maximum number of genotypes (68) followed by Cluster II (6). All other 6 clusters consisted of 1 genotype each. Among 8 clusters, cluster II showed highest intra cluster distance (342.14) followed by cluster I (279.07), whereas minimum intra cluster distance recorded in cluster III, cluster IV, cluster V, cluster VI, cluster VII and cluster VIII (0.00). Based on inter-cluster distance the maximum diversity was observed between clusters VIII and VI (3234.85). D2 statistics showed that potassium content contributed highest (25%) to divergence followed by magnesium content (22.7%) and manganese content (11%). Principal component analysis revealed that the first two principal components (PCs) together controlled 52.92% of total variability. Based on higher genetic distance among clusters and higher mean value of genotypes for nutritional traits, DWM 164, DWM 129, DWM 165, DWM 115, DWM 142, DWM 117, DWM 45, DWM 196 and DWM 12 could be exploited in breeding programme as potential donors for developing nutrient- rich watermelon varieties/hybrids.