Two field experiments were established during the two successive seasons (1997/98 and 1998/99) to study the effect of inoculation with non-symbiotic N2-fixers (Azotobacter chroococcum and Azospirillum brasilense) in the presence of biogas manure or inorganic N-fertilizer on growth; yield and chemical constituents of anise plants. Results showed that CO2 evolution and nitrogenase activity of anise plant rhizosphere were the highest in the treatments of Azotobacter chroococcum provided with half dose of either biogas manure or inorganic N-fertilizer. Also, inoculation of anise seeds with Azotobacter or Azospirillum in the presence of half dose of biogas manure recorded the highest values of azotobacters and azospirilla densities.
Results also revealed that there were significant increases in vegetative growth; seed yield; essential oil; carbohydrates; chlorophylls; carotenoids; total nitrogen; total phosphorus and total potassium content of anise plants due to inoculation with non-symbiotic N2-fixers and half dose of biogas manure. G.L.C. analysis of seeds volatile oil showed that, trans-anethole was the main component in all treatments. Inoculation with either Azotobacter or Azospirillum provided with half dose of inorganic fertilizer gave the highest percentage of trans-anethole.Key words: Anise, Biofertilization, Azotobacter, Azospirillum, volatile oil, biogas manure.
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