EFFECTS OF IRRIGATION AND NITROGEN ON THE YIELD COMPONENTS OF FENNEL (FOENICULUM VULGARE MILL)

A field experiment was conducted to study the effects of irrigation an d nitrogen applied at different growth stages on the oil and anethole yields of fennel (Foeniculum vulgare Mill.), and its yield components. Irrigation increased the yield of whole plant dry matter, with the st em elongation stage being the most sensitive. Full irrigation and irri gation applied during the flowering and late flowering growth stages i ncreased umbel and oil yields. Irrigation during the late flowering st age made the greatest contribution to oil yield, accounting for >80% o f the yield due to full irrigation. This was attributed to the concurr ent timing of irrigation during the late flowering stage with dry cond itions and the development of the main oil-bearing structures, the sec ondary and tertiary umbels. Irrigation had no significant effect on th e anethole concentration of the oil. The best economic return was achi eved by irrigating during the late flowering stage. There was no signi ficant effect of nitrogen on any of the yield components measured in t his study.