Competitive Effects of Lambsquarters (Chenopodium album) on Growth Parameters, Seed Yield and Essential Oil of Fennel (Foeniculum vulgare)

To evaluate competition between lambsquarters (Chenopodium album) and fennel (Foeniculum vulgare) on some traits effective on growth and yield a factorial experiment was conducted during 2010-2011 in Agricultural Research Station of Islamic Azad University, Tabriz Branch, Iran, based on randomized complete blocks design with 3 replications. Treatments were weed density (0, 2, 4, 6 and 8 plants per meter row) and its relative emergence times (simultaneously, 10, 20 and 30 days after crop emergence). Dormancy in lambsquarters seeds was broken using gibberlic acid. Essential oil of seeds was extracted by celevenger type apparatus. Results indicated that emergence of 4 weed plants per meter row had no significant effect on fennel growth period. When weed density increased more than 4 plants per meter row, leaf chlorophyle content index increased 26%. Effect of higher weed densities on the time of leaf senescence appearance and plant height was more than lower weed densities. Reduction of weed density and delaying its time of relative emergence decreased weed biomass. While, seed and essence yield increased, significantly. In those weed densities higher than 4 plants per meter row essence yield reduced 25 mL ha-1 per weed. It seems that the weed control in fennel field is necessary.