Genetic variability for phytochemical components in fennel genotypes

Abstract Fennel ( Foeniculum vulgare Mill.) is an important medicinal plant and has several subspecies and varieties. In this study, 20 fennel genotypes belonging to four important subspecies and/or varieties from 17 countries were evaluated for essential oil components, seed yield, and essential oil content during 2 yr (2015–2016). High genotypic variation was observed among and within subspecies and/or varieties for all the measured traits. Based on the gas chromatography–mass spectrometry analysis, transanethole (22.37–86.47%), estragole (2.47–25.86%), fenchone (4.96–19.79%), and limonene (0.53–11.87%) were detected as major essential oil components. Comparing the subspecies and/or varieties showed that the ssp. piperitum had the highest average of limonene and estragole, and the lowest average of transanethole and seed yield. Based on the principal component analysis, var. vulgare , var. dulce , and var. azoricum were categorized in one group, and ssp. piperitum was separately grouped, confirming two major separate subspecies. The highest essential oil content was observed in the second year in all the subspecies and varieties. However, the studied subspecies and/or varieties had different values of phytochemical traits across the years. The negative correlation between some essential oil components indicates that some components are isomers and it can limit the simultaneous selection of components. The high variation in the studied germplasm may be utilized to select useful samples for medicinal, industrial, and other purposes.