الفهرس 
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Abstract
SUMMARY AND CONCLUSION
The experiment was carried out at the Experimental Farm of Faculty of Agriculture, Ain Shams University, Cairo, Egypt, during two successive seasons of 2018/2019 and 2019/2020.
This study aims to evaluate the ability of bio-fertilizer mixture and rationalization of mineral fertilization to enhance the production of fennel and reduce chemical fertilizer application, as well as, to increase the anethole as an active ingredient instead of estragole, which is an undesirable component.
In a pot experiment, seeds of fennel (Foeniculum vulgare Mill) were sown in a mixture of sand and compost (3:1) in seventeen levels of fertilization in a completely randomized design with four replicates. The fertilization levels were a mixture of bio-fertilizer containing Azotobacter chroococcum, Bacillus circulans, and Vesicular-arbuscular mycorrhiza which was in liquid form, alone or with the proportions of the recommended dose of chemical NPK, and the full recommended dose of NPK has been used as a control.
Mixture of three bio-fertilizer strains added once (after one month of planting), twice (first addition was a month after sowing and the second was a month after the first addition), three times (first addition was a month after sowing and a month separates the addition and another), or four times (first addition was a month after sowing and a month separates the addition and another) in proportions as follow:
5 ml/pot bio-fertilizer only.
3.75 ml/pot bio-fertilizer with 25% of the recommended dose of NPK.
2.5 ml/pot bio-fertilizer with 50% of the recommended dose of NPK.
1.25 ml/pot bio-fertilizer with 75% of the recommended dose of NPK.
Control (Full dose of NPK as recommended doses).
6.1 The obtained results could be summarized as follows:
6.1.1. Effect of inoculation with Azotobacter chroococcum, Bacillus circulans and VAM per pot either separate or in combination with chemical fertilizer on different plant growth parameters of fennel.
The different fertilization levels had significant effects on plant growth parameters of fennel. Data showed that bio-fertilization mixture at the rate of 3.75 ml/pot with 25% of mineral fertilization gave the highest plant when the mixture added twice (T6), and when added four times (T8), the number of branches/plant, root length, fresh and dry weight of plant, fresh and dry weight of root significantly increased compared to bio- or chemical fertilization only.
6.1.2. Effect of inoculation with Azotobacter chroococcum, Bacillus circulans and VAM per pot either separate or in combination with chemical fertilizer on yield measurements of fennel.
The different fertilization levels had significant effects on yield measurements of fennel. Data showed that bio-fertilization mixture at the rate of 3.75 ml/pot added four times with 25% of mineral fertilization (T8) significantly increased the umbels number, fruit yield per plant and seed index compared to bio- or chemical fertilization only.
6.1.3. Effect of inoculation with Azotobacter chroococcum, Bacillus circulans and VAM per pot either separate or in combination with chemical fertilizer on essential oil of fennel.
The different fertilization levels had significant effects on essential oil of fennel. Data showed that the highest percentage of estragole (83.37 %) was obtained by applying 3.75 ml/pot bio-fertilizer added three times + 25 % NPK (T7), limonene (20.58 %) by applying 2.5 ml/pot bio-fertilizer added three times + 50 % NPK (T11), anethole (12.77 %) by applying 3.75 ml/pot bio-fertilizer added once + 25 % NPK(T5), 1.8 cineol (10.60 %) and α-pinene (2.90 %) by applying 100 % of NPK. However, the lowest percentage of estragole (68.61 %) was obtained by applying 100 % of NPK, limonene (7.40%) by applying 3.75 ml/pot bio-fertilizer added three times + 25 % NPK (T7), 1.8 cineol (1.62 %) by applying 2.5 ml/pot bio-fertilizer added three times + 50 % NPK (T11), anethole (0.14%) and α-pinene (0.72 %) by applying 1.25 ml/pot bio-fertilizer added once + 75 % NPK (T13).
6.1.4. Effect of inoculation with Azotobacter chroococcum, Bacillus circulans and VAM per pot either separate or in combination with chemical fertilizer on chemical compositions.
The different fertilization levels had significant effects on essential oil of fennel. Data showed that adding 3.75 ml/pot of bio-fertilizer mixture four times with 25% of chemical fertilization (T8) increased the uptake of nitrogen, phosphorus and potassium compared to bio- or chemical fertilization only.
6.1.5. Effect of inoculation with Azotobacter chroococcum, Bacillus circulans and VAM per pot either separate or in combination with chemical fertilizer on microbial studies.
The different fertilization levels had significant effects on microbial studies of fennel. Data showed that adding 3.75 ml/pot of bio-fertilizer mixture four times with 25% of chemical fertilization (T8) significantly increased total microbial count and cumulative CO2-C on fennel rhizosphere compared to chemical fertilization only.
Conclusion:
The addition of bio-fertilizers Azotobacter chroococcum (108 CFU), Bacillus circulans (108 CFU) and VAM (200 spores) enhanced plant rhizosphere and microbial activity for the fennel root, which leads to increased uptake of the three major elements (N, P and K) and thus increased vegetative growth, enhanced the essential oil percentage and its component. from the overall results, we can recommend that the addition of 3.75 ml. of bio-fertilizer mixture (Azotobacter chroococcum, Bacillus circulans and VAM) four times with 25% of the recommended dosage of chemical fertilizer can enhance the productivity of fennel.