Multivariate analysis of morpho-chemo variations in Anethum graveolens L. accessions

Understanding the genetic diversity and trait relationships in Anethum graveolens L. (dill) is essential for breeding high-yielding cultivars with enriched biochemical profiles suited to various growing conditions. This study characterized 25 Iranian dill accessions originating from distinct agro-climatic regions by evaluating their morphological, biochemical, and essential oil (EO) profile. A randomized complete block design field trial with three replications was conducted in Ardabil, Iran. Morphological traits, including biomass and yield-related parameters, were recorded at both flowering and physiological maturity stages. Biochemical analyses included quantification of chlorophyll pigments, total phenolic content, anthocyanins, proline, and EO profile determined using Gas Chromatography-Mass Spectrometry. Considerable genetic variability was observed among accessions for all measured traits. EO content reached a maximum of 1.43%, while plant fresh and dry weight also exhibited significant variation, indicating promising genetic sources for yield and biochemical improvement. High coefficients of variation were identified for carvone, limonene, α-pinene, and proline, suggesting their potential for targeted selection. Factor analysis extracted ten principal components that collectively accounted for 83.8% of the total variance, grouping traits related to yield capacity, reproductive traits, pigment composition, and EO constituents. The fourth factor, defined by high loadings of carvone, α-pinene, and limonene, was indicative of aromatic quality. Cluster analysis segregated the accessions into three primary groups, with Cluster-I comprising accessions demonstrating superior biomass production, seed yield, and EO content. These high-performing accessions (G8-Sarab, G19-Astara, G21-Dezful, G24-Rezvanshahr, and G25-Hamedan-2) originated from contrasting climates, suggesting considerable adaptability and breeding value. Traits were similarly clustered into four main groups reflecting agronomic, photosynthetic, yield, and EO profile, corroborating factor analysis results. The identified accessions represent valuable genetic resources for breeding programs focused on enhancing dill productivity, EO characteristics, and resilience, supporting its sustainable production across diverse agro-ecological systems.