Evaluation of morphological diversity and phenotypic relationships among wild populations of tarragon (Artemisia dracunculus L.) germplasm from Iran

This study evaluated the diversity and relationships of morphological traits in seven tarragon (Artemisia dracunculus L.) genotypes collected from various regions of Iran (Raviz, Jorjafk, Baft, Ardakan, Kashan, Isfahan, and Dehshad) using a completely randomized design with four replications. Analysis of variance revealed significant differences (p < 0.01) among genotypes for all recorded traits, except internode length, the ratio of fresh weight to dry weight, and the ratio of leaf dry weight to stem dry weight. Significant variations were observed in vegetative traits, including stem length, stem diameter, plant diameter, number of auxiliary branches, and total fresh weight. The Dehshad (Tehran) population exhibited superior vegetative traits, while the Ardakan population showed the lowest mean values for these traits. Correlation analysis indicated that elevation of sampling sites was positively correlated with leaf length, internode length, the ratio of leaf dry weight to stem dry weight, and the number of unhealthy leaves. Principal Component Analysis (PCA) extracted four components with eigenvalues greater than 1 (Kaiser criterion), cumulatively explaining 99.6% of the total phenotypic variance. The first two components accounted for 84.2% of the variance, representing vegetative growth indices and dry matter yield-related traits. Cluster analysis based on morphological traits, using Ward's method with Euclidean distance, divided the seven populations into two main clusters at a Euclidean distance of approximately 11.48. At a lower distance threshold of 7.65, three distinct clusters were identified. High heritability was observed for plant height, stem diameter, number of main branches, number of auxiliary branches (> 5 cm), leaf area, and total fresh weight, attributed to the uniform experimental environment. These findings provide a preliminary assessment of the phenotypic variation present among Iranian tarragon wild populations. This morphological characterization can serve as a foundation for selecting promising accessions for further evaluation in breeding programs. However, we acknowledge that molecular marker studies and multi-year field trials are necessary to validate the genetic basis of the observed diversity and to inform conservation strategies.