Genetic Variation in Essential Oil Constituents of Fennel (Foeniculum vulgare Mill) Germplasm

Abstract

Ninety one fennel (Foeniculum vulgare Mill.) germplasm lines collected from various geographical locations in India were evaluated for their essential oil content and its composition. Essential oil content ranged from 1.0 to 3.3%. Maximum lines had 2–3% essential oil. In all the germplasm lines eleven major compounds including α-pinene, camphene, β-pinene, myrcene, cymene, γ-terpinene, 4-allyl anisole/methyl chavicol or estragol, anethole, geranyl acetate and p-anisaldehyde were detected . Anethole was most abundant compound in all fennel germplasm lines which ranged from a minimum of 9.15% to a maximum of 96.64% with an average of 44.33%.Another predominant compound observed in essential oil of fennel germplasm lines was 4-allyl anisole/methyl chavicol or estragol, content of which ranged between 2.04 to 83.01%. A group of terpenoids consisting of α-pinene, camphene, β-pinene, myrcene, cymene and γ-terpinene accounted for 0.18 to 18.66% of essential oil of which γ-terpinene was contributed from a minimum of 0.13 % to a maximum of 14.95%. A significant negative correlation (r = -0.98) was observed between related compounds anethole with 4-ally anisole and γ-terpinene (r = -0.42). Further, the germplasm lines were grouped in different classes as per major essential oil constituents viz., anethol, γ-terpinene and 4-allyl anisole. Cluster analysis was done using ward’s method based on the value of γ-terpinene, 4-ally anisole and anethole+estragol which resulted in to seven distinct groups of 91 germplasm lines.