leaf appearance rate and seed yield of fennel (foeniculum vulgare l.) as affected by interfering effects of lambsquarters (chenopodium album l.)

in order to evaluation of seed production index in lambsquarters (chenopodium album), leaf appearance and yield of fennel (foeniculum vulgare) under inter-specific competition a factorial experiment was conducted in islamic azad university, tabriz branch, iran, during 2011-2012. treatments were weed densities of 0, 2, 4, 6 and 8 plants per meter row and its relative emergence times of simultaneously, 10, 20 and 30 days after crop based on randomized complete blocks design in 3 replications. dormancy in lambsquarters seeds was broken using gibberlic acid. results indicated that 8th leaf in fennel appeared after 35.4 days. time to appearance of 12th leaf in 0-4 weed plants per meter row was 50 days, while, in higher weed densities delayed averaged 11.5 days. with decreasing weed density and delaying it,s emergence time fennel seed yield increased. essential oil yield of fennel reduced 25 ml ha-2, per weed plant. when lambsquarters density decreased and emerged after fennel, it,s seed production index reduced under competition with fennel. in those treatments which lambsquarters plants emerged along with the crop, seeds production weight was 9.8% of total plant weight, while, in other levels of lambsquarters emergence time were 5.8%, 3.6% and 3.8%, respectively. in this study, treatments with higher biomass production in lambsquarters had greater weed seed production per square meter and lower seed yield in fennel, that it could be used for lambsquarters management in fennel fields.