Selection of essential oil rich populations of bitter fennel (Foeniculum vulgare MILL. ssp vulgare var. vulgare) with reduced estragole content

The aim of the investigations was to explore the genetic potential of bitter fennel (Foeniculum vulgare MILL. ssp. vulgare var. vulgare) with respect to the development of populations with high essential oil content and minimised content of estragole which is claimed to be a risky substance. The four consecutive selection steps started from a population generated by crossing. Keeping the minimum level of 60% anethole in the essential oil required by PhEur, a relative improvement of the essential oil content of the fruits by 47% (from 8.29 to 12.2%) and a lowering of the estragole content by 23% (from 2.65 to 2.04%) have been accomplished. The fenchone content of the essential oil could be kept in every case on a level >15% required by PhEur. it can be assumed that breeding of fennel varieties with essential oil contents up to 15% is feasible. However, lowering of the estragole content is limited due to the positive correlation of estragole and anethole. Maintaining the mimum anethole content required by PhEur, the estragole content can probably not be lowered below 2.2-2.1%.