Effect of mycorrhiza fungus ( Glomus mosseae) and growth-promoting bacteria (Azospirillum) on agronomical and essential oil of Fennel (Foeniculum vulgar) under drought stress in two habitats of Fars province

Fennel (Foeniculum vulgar Mill) is one of the most important medicinal plants of the Umbelliferae family, which is cultivated mainly for the use of seeds and essential oils in various pharmaceutical, food and cosmetic industries (Norouzi Shahri et al., 2015). The medicinal plant of fennel in Iran is widely distributed in the regions of Khorasan, Tehran, Gorgan, Mazandaran, Kurdistan, Kerman, Gilan and Tabriz, and grows up to three meters above sea level. Plants face a variety of biological and non-biological stresses during growth. Drought stress is one of the most important abiotic stresses that reduces growth and yield in many crops and medicinal plants (Kabiri et al., 2014; Bahrani et al., 2013). Mycorrhizal fungi have several functions in the ecosystem of crops; so that it improves the physical quality of the soil, the chemical quality of the soil and the biological quality of the soil. Mycorrhiza has been reported to increase biomass, essential oil content, and ultimately essential oil function in medicinal plants (Hatami and Ghorbanpour, 2016; Ghorbanpour et al., 2014). The use of biofertilizers including Azotobacter, Azospirillium and phosphate-soluble bacteria has significant effects on the essential oil of marjoram. Growth-promoting bacteria may accumulate in the rhizosphere, root surface, or even the intracellular space of plants (Zafari et al., 2018; Bahrani et al., 2010). In general, the aim of this study was to investigate the effect of application of mycorrhiza and growth-promoting bacteria Azospirillum under drought stress on morphological traits and fennel essential oil in Zarghan and Kodian regions that have different climatic conditions.

An experiment was carried out to investigated the effect of mycorrhiza (Glomus mosseae) and growth promoting bacteria (Azospirillum) in drought stress on agronomic and biochemical characteristics of Foeniculum vulgar, in 2019-2020 crop season in two regions (Kodian, Zarghan) of Shiraz, Fars province, Iran. The experiment was done as a factorial split plot in a randomized complete blocks design with three replications. Main plots were drought stress at three levels: 30% (control), 60% and 90% field capacity and sub-plots were mycorrhiza, at two levels (no inoculation, and seed inoculation with Fungal) and also Azospirillum at two levels (no inoculation and seed inoculation with bacteria).

The results showed that inoculation of Glomus mosseae and Azospirillum had significant effect on grain yield, biological yield, thousand seed weight, plant height, number of umbrellas per plant, essential oil yield and percentage in both regions and improved the negative effects of drought stress. The highest seed yield in both places belonged to the treatment of 30% field capacity with inoculation of mycorrhiza and Azospirillum. Mycorrhiza and Azospirillum reduced the negative effects of drought stress and increased all morphological and biochemical characteristics.

In general, interaction of mycorrhiza and Azospirillum consumption in no drought stress can be suggested to maximize morphological and biochemical characteristics of Fennel under the same weather conditions of the study.