Changes in the essential oil yield and composition of dill (Anethum graveolens L.) as response to arbuscular mycorrhiza colonization and cropping system

Abstract

Intercropping and arbuscular mycorrhizal (AM) fungi application are thought to be useful means of minimizing the risks of agricultural production in many environments. Hence, this work was conducted to study and compare the effectiveness of AM fungi (Funneliformis mosseae) on growth, chlorophyll content, shoot water content, land equivalent ratio (LER) and essential oil (EO) yield and composition of dill in different cropping systems. Two experiments were carried out with factorial arrangement based on randomized complete block design with three replications in 2013 and 2014. The factors were cropping systems including (a) common bean (Phaseolus vulgaris L.) sole cropping (40 plants m−2), (b) dill (Anethum graveolens L.) sole cropping at different densities (25, 50 and 75 plants m−2) and (c) the additive intercropping of dill+common bean (25+40, 50+40 and 75+40 plants m−2). All these treatments were applied with (+AM) or without (−AM) arbuscular mycorrhiza colonization. In both cropping systems, the AM colonization significantly increased chlorophyll content, LER and EO yield as compared to non-inoculated plants. Changes in EO composition were detected in inoculated and intercropped dill plants. The content of α-phellandrene, limonene, β-phellandrene, terpinen-4-ol, cryptone and carvone were enhanced in EO obtained from AM-inoculated and intercropped dill plants, while AM colonization resulted in a lesser content of α-terpinene, p-cymene, α-terpinolene, p-α-dimethylstyrene, dill ether, n-dihydrocarvone and cis-sabinol at sole cropped dill plants.