Genetic diversity analysis of tamarind (Tamarindus indica L.) based on morpho-biochemical traits for identification of superior genotypes

Abstract

Abstract

The present study aimed to assess the trait correlations and genetic diversity among 25 tamarind ( Tamarindus indica L.) genotypes based on 15 morphological and 8 biochemical traits to identify superior genotypes. Substantial variability was observed with all traits, with coefficients of variation ranging from 1.11 (tartaric acid) to 14.27% (rag weight /pod). Pod length ranged from 11.99 to 25.19 cm, pod width (2.91–4.88 cm), pod weight (20.84–55.14 g), with pulp, shell and rag weights ranging from 9.47 to 33.33 g, 4.33–11.05 g and 1.01–7.48 g, respectively and pulp-to-shell ratio of 1.10 to 3.97. Yield per plant varied from 22.00 to 154.00 kg, while seed length, width, weight per pod and number of seed ranging from11.80–19.47 mm, 9.73–17.67 mm, 4.23–8.58 g and 4.83–8.83, respectively. Among biochemical traits such as TSS, titratable acidity, total sugars, crude fiber, tartaric acidand protein content was ranged from 13.20 to 34.42 °Brix, 1.68–12.10%, 23.94–53.79%, 3.37–12.57%, 1.64–14.62% and 2.56–10.68%, respectively. Pearson’s correlation analysis revealed 49 significant positive and 5 negative associations, with strong positive correlations between pod weight and pulp weight ( r = 0.88), pulp recovery and pulp to seed ratio ( r = 0.83), and total sugars with reducing sugars ( r = 0.73), while fruit set showed a strong negative correlation with fruit drop ( r = − 1.00). Principal component analysis (PCA) revealed that the first two components explained 46.00% (PC1 29.40% and PC2 16.60%) of the total variability. Hierarchical clustering heatmap (HCH) grouped the genotypes into three clusters, with Cluster III (52.00%; n = 13) as the major cluster, including sub-clusters III-B (36.00%; n = 9) and III-A (16.00%; n = 4), followed by Cluster II (36.00%; n = 9) with sub-clusters II-B (32.00%; n = 8) and II-A (4.00%; n = 1), and Cluster I (12.00%; n = 3) with sub-clusters I-B (8.00%; n = 2) and I-A (4.00%; n = 1), representing considerable genetic divergence among the genotypes. The study identified NFN-4, NFN-5 and NFN-10 as superior genotypes due to their superior performance with yield, pulp recovery and sugar qualities. These genotypes can be utilized as potential parents in future breeding programme aimed at developing climate-resilient and high-quality cultivars.