Abstract
Grammosciadium platycarpum (GP), a perennial member of the Apiaceae, is a valuable source of linalool-rich essential oil with pharmaceutical and industrial significance. Despite this, Iranian populations remain poorly studied, limiting conservation and genetic utilization efforts. This study aimed to comprehensively evaluate fourteen Iranian G. platycarpum populations cultivated under uniform environmental conditions, assessing morphological traits, essential oil composition, and phytochemical diversity. Seeds were collected and grown in a randomized block design, enabling precise comparison of traits. Considerable variability was detected, with the largest coefficients of variation observed for umbrellas per plant, leaf width, fruit dry weight (FDW), essential oil yield (EOY), chlorogenic acid content, and leaf length. Shoot dry weight (SDW) ranged from 31.0 to 89.88 g per plant, while fruit biomass varied from 6.52 to 28.0 g, with GP2 representing the extremes. Essential oil content (EOC) ranged between 0.74 and 1.24%, with GP5 displaying the maximum and GP12 the minimum values. GP5 also achieved the highest EOY (0.94 g per plant), whereas GP10 exhibited the lowest (0.23 g). GC-FID and GC-MS analyses identified 97.55-99.93% of essential oil constituents, predominantly linalool (71.34-82.31%) and limonene (9.32-13.14%). Fruit extracts revealed ferulic acid, chlorogenic acid, and rutin as major phenolics, varying significantly among populations. Genetic parameters indicated high heritability and genetic advance for traits such as umbrellas per plant, leaf width, fruit mass, and EOY, suggesting additive gene action. Path coefficient analysis demonstrated SDW, EOC, and ferulic acid as direct determinants of oil yield, whereas linalool concentration was closely related to phenolic content, chlorogenic acid, and plant height. Overall, the results highlight substantial genetic and biochemical diversity in G. platycarpum, offering valuable insights for targeted breeding, germplasm conservation, and sustainable domestication of high-linalool cultivars.