Responses of field grown fennel (Foeniculum vulgare Mill.) to different mycorrhiza species under varying intensities of drought stress

•Mycorrhiza symbiosis could enhance drought tolerant in fennel plants.•Benefit of mycorrhiza under drought stress was due to the enhancement of osmotic adjustment.•G. mosseae was found to be more efficient under drought stress than G. intraradices.

The influence of colonization of fennel (Foeniculum vulgare Mill.) roots by two different species of arbuscular mycorrhizal (AM) fungi (Glomus mosseae and Glomus intraradices) and different irrigation treatments (well-watered, moderate water deficit stress, severe water deficit stress and very severe water deficit stress) were examined on growth, osmotic adjustment and qualitative and quantitative yield during two consecutive growing seasons. The experiments were conducted at Yasouj University, Yasouj, Iran located in semi-arid region of Iran. The results indicated that irrespective of mycorrhizal species and water deficit stress intensity, inoculated seeds produced taller plants, more dry matter and seed yield as well as seed essential oil content compared with non-inoculated plants. In both years of the experiment and in AM free plots, irrigation treatments showed a significant effect on leaf P concentration so that P concentration decreased with increasing water deficit stress intensity. Interestingly, mycorrhizal inoculation increased P accumulation and soluble sugars in fennel leaves compared with control plants. The data presented in this study suggest that different AM fungi species even within the same genus have distinct effects on fennel growth and yield. Overall, the results showed that G. mosseae was more efficient under water deficit stress. The application of AM fungi could be critical in cultivation of fennel under arid and semi-arid conditions, where water is the most important factor in determining plant growth and yield.

Graphical abstractInoculation of fennel plants with arbuscular mycorrhizal (AM) fungi in drought stress conditions results in higher seed yield production than non-AM fennel which received full irrigation.Download high-res image (66KB)Download full-size image