Multivariate analysis of morphological variables in tamarind (Tamarindus indica L.)

Background Tamarind (Tamarindus indica L.) is a tree belonging to the Fabaceae family. This tree grows in subtropical and semi-arid tropical regions, and it is particularly common in India, Africa, and Southeast Asia. In this study, the morphological variations of 55 tamarind accessions collected from two areas of Sistan-va-Baluchestan province in Iran were evaluated using correlation matrix, principal component, and hierarchical cluster analyses based on 61 variables. Results One-way ANOVA (p < 0.05) showed significant differences among the examined accessions. The coefficient of variation (CV) ranged from 8.50% (lateral petal width) to 110.44% (flesh adherence to skin). 45 out of 61 traits (73.77% in total) had a CV greater than 20.00%. This value indicated that there was a high degree of variation among the examined accessions. Leaf length ranged from 35.38 to 97.68 mm, leaf width from 17.98 to 33.65 mm, fruit length ranged from 33.23 to 127.24 mm, and fruit seed weight from 0.65 to 9.79 g. Tree growth vigor, tree height, and branch flexibility were dominant with high values (28, 33, and 29 accessions, respectively). Peak of fruiting season was classified as late-April (15 accessions) and early-May (40 accessions). The obtained correlation data indicated significant relationships between leaf length and leaf width (r = 0.646**), fruit length and fruit weight (r = 0.710**), as well as fruit length and fruit seed weight (r = 0.599**). According to the principal component analysis, the first 17 principal components explained 83.28% of the total variation. The accessions are distributed across the four regions of the scatter plot. There were 15 accessions in cluster 1, 11 accessions in cluster 2, 18 accessions in cluster 3, and 11 accessions in cluster 4. According to the hierarchical cluster analysis, four clusters were formed, with the highest number of accessions in the B2 subgroup (34 accessions). The first 20 accessions were determined based on their individual quantitative trait performances, with the best results listed as follows: Bahoukalat-37, Bahoukalat-36, Bahoukalat-31, Bahoukalat-33, Tis-10, Bahoukalat-32, Bahoukalat-2, Bahoukalat-16, Bahoukalat-1, Tis-8, Bahoukalat-4, Bahoukalat-10, Tis-7, Bahoukalat-6, Bahoukalat-3, Bahoukalat-34, Tis-1, Bahoukalat-5, and Bahoukalat-29, respectively. Conclusions This study addresses key gaps in tamarind research, offering important insights into its genetic diversity and morphological traits. The results are expected to be a valuable resource for plant breeding programs, supporting the development of more adaptable and sustainable tamarind varieties. Further studies on accessions from diverse ecological conditions could deepen our understanding of its genetic diversity and aid future breeding efforts.