Response of fennel [Foeniculum vulgare Mill] to inoculation with diazotrophs, inorganic nitrogen fertilization and biogas manure

ABSTRACT

Two Field experiments were accomplished at the Experimental Farm. Faculty of Agriculture, Ain Shams University, Shobra El-Kheima, Cairo, Egypt to evaluate the growth, productivity and quality of Fennel [Foeniculum vulgare, Mill] as affected by three different sources of nitrogen fertilization. Ammonium nitrate was applied at the rate of 0, 40, 60 and 80 kg N/fed as a source of inorganic nitrogen fertilization. Biogas manure used as organic fertilizer with the levels 0. 40 and 60 kg N fed as well as inoculation with a mixture of Azotobucter chroococcum + Azospirillum lipoferum as biofertilizers. Irrespective of concentrations, inorganic fertilizer surpassed to other fertilizers. The highest values of growth parameters, oil percent, yields of fruits and oil, nitrogen and protein contents and nitrogen uptake were obtained by application 80 kg N/fed. of inorganic nitrogen. Soil inoculation with a mixture of diazotrophs significantly overcame the fruits inoculation with the same mixture for the previously mentioned parameters. Biogas manure application at 60 kg N/fed. produced the highest values of all tested parameters in comparison with biofertilizers and control. The biofertilizers as such or combined with inorganic nitrogen augmented all measuring parameters in comparison with uninoculated plants. Furthermore, soil inoculation with a mixture of the two N2 fixers and supplemented with inorganic nitrogen 60 kg N/fed. produced the highest values of growth parameters, oil content, yields of fruits and oil in comparison with control. The percentage of increases were 23.01, 129.7, 63.01, 98.02, 301.87, 112.77, 53.79 and 86.79 in comparison with control consecutively. Meanwhile application biogas manure at 60 kg N/fed. + 80 kg inorganic N/fed. significantly induced the best records of all tested parameters. In addition, biogas manure [Bio2] produced the highest values of nitrogen and protein contents and nitrogen uptake. Furthermore, biofertilized plants which received inorganic nitrogen [80 kg N/fed.] came at the second order for nitrogen and protein contents and nitrogen uptake compared to biogas manure + 80 kg inorganic N/fed. ln concern to essential oil constituents GC analysis of the fruits oil indicated that estragole, limonene, fenchone and anethole are the main compounds of the oil. It was found that the relative percentage of the oil constituents were fluctuated as a result of interaction between all fertilization sources. In terms of fenchone compound, which is responsible for fennel bitterness. the interaction between inorganic N and bio-organic fertilizers reduced its relative percent. this mean more favorable taste for the essential oil if used for food dressing.Inoculation with diazotrophs caused an increase in total microbial count. azotobacters and azospirilla densities in fennel rhizospheric soil. Rate of CO2 evolution in the rhizosphere of fennel was affected by soil and fruits bacterization the increasing was higher in the soil inoculation treatment than the other one .Application of biogas manure and inorganic N-fertilizers at the rate of 60 and 80 N kg fed. respectively gave the maximal densities of diazotrophs and total microorganisms and the highest rate of CO2 evolution after 100 days of planting