Effects of Organic, Biologic and Chemical Nitrogen Fertilizers on Fennel (Foeniculum vulgare Mill.) Yield and Essential Oil

Abstract

In order to investigate the effects of different nitrogen nutritional systems including chemical, organic and biologic ones on yield and essential oil content, yield and constituents of this valuable medicinal plant, a field experiment was carried out in 2013-2014 agricultural season in completely randomized blocks design. Different nitrogen system treatments consisting of: 1. N1 or control (Uniformly spreading urea fertilizer in the plot, 50% at planting time and 50% at stem elongation), 2. N2 (Uniformly spreading 50% of urea fertilizer in the plot at planting time and spraying the other 50% of urea fertilizer at stem elongation on fennel foliage), 3. N3 or cow manure, 4. N4 or bio-fertilizer (Inoculation of fennel seeds with Azotobacter and Azospirillum), 5. N5 or Integrated-1 (Cow manure + uniformly spreading urea fertilizer in the plot at stem elongation), 6. N6 or Integrated-2 (Cow manure + bio-fertilizer) were applied. Results showed that urea spraying has led to 13.4% more seed yield production than control with 3.28% essential oil content which was as well as control. Moreover, the findings showed that replacing 50 percent of required nitrogen with cow manure in fennel, could lead to a favorable quantitative and qualitative seed production as well as the treatments which used 100 percent of nitrogen as chemical fertilizers. Other finding of the present study, showed that seed inoculation with biofertilizer (Azotobacter + Azospirillum) had no positive effect on plant seed yield and essential oil.