An experiment based on randomized complete blocks design with five treatments in three replications was carried out to investigate the effect of bio- and chemical fertilizers on growth traits and essential oil of fennel plants (Foeniculum vulgare Mill). The results showed that inoculation of bio-fertilizers applied with 50% recommended dosage of chemical fertilizers of nitrogen and phosphorus, increased vegetative growth (plant height, number of branches per plant, plant dry weight) of fennel plants compared to chemical fertilizer treatments only. Plants treated with mixture of bio-fertilizers (arbuscular mycorrhizalmy strain Sebacina vermifera and phosphate dissolving bacteria genera Peseudomonas) had the highest plant height (72.6 cm), number of branches per plant (8.5), number of umbels per plant (45.5), dry weight (36.2 g) and fruit yield per plant (7.7 g). Application of bio-fertilizers also increased the amount of nitrogen, phosphorus and potassium in plant tissues compared to non-inoculated plants. Plants treated with mixture of bio-fertilizers had the highest amount of nitrogen (14.1 mg g-1 dry weight), phosphorus (8.2 mg g-1) and potassium (9.2 mg g-1) in their tissue while the least amount of N (8.9 mg g-1), P (4.7 mg g-1) and K (5.9 mg g-1) occurred in plant tissues treated with half recommended dosage of N and P fertilizers. The highest essential oil yield was also observed with the treatment of bio-fertilizer plus half recommended dose of chemical fertilizer. However, the least amount of essential oil yield was obtained in plants treated with half dose of chemical fertilizer.

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