عنوان مقاله [English]
To evaluate seed production index of lambsquarters (Chenopodium album L.), leaf appearance rate and yield of fennel (Foeniculum vulgare L.) under inter-specific competition a factorial experiment was conducted in Islamic Azad University, Tabriz Branch, Iran during 2011-2012 growing season based on randomized complete blocks design with three replications. Factors included five weed densities 0, 2, 4, 6 and 8 plants per meter row and its relative emergence times of simultaneously sown 10, 20 and 30 days after fennel emergence. The 8th leaf in fennel appeared after 35.4 days. Time to appearance of the 12th leaf in weed densities of 0-4 plants per meter row was 50 days, while in higher weed densities it was delayed about 11.9 days. Fennel seed and essential oil yields increased with decreasing weed density and delay in its emergence time. Low density and late emergence of lambsquarters caused seed production index to decrease. In simultaneously sown treatments, seeds production index was 9.8% while, in treatments of 10, 20 and 30 days after fennel emergence it was decreased to 5.8, 3.6 and 3.8%, respectively. In this study, treatments with higher biomass production of lambsquarters resulted in greater weed seed production and lower seed yield in fennel, being important for lambsquarters management in fennel fields.