Light Interception and Radiation use Efficiency (RUE) of Sesame Cultivars as Affected by Interference the Redroot Pigweed (Amaranthus retroflexus L.) Different Densities

Field experiment was carried out during 2008 growing season at the research farm of University of Tehran, Karaj, Iran, to evaluate the interference effects of redroot pigweed (Amaranthus retroflexus L.) on light interception and RUE of four Sesame cultivars. Experimental design was a randomized complete block with three replications per treatment. The first factor was the sesame cultivars including, Otlan (Multiculum), Varamin 2822, Naz Uniculm and Karaj 1 (Uniculm cultivars). The second was the redroot pigweed density at five levels: 0, 2, 4, 8, and 16 plant m2. The results indicated that leaf area distribution in the canopy has a triangular function and the height, in which maximum leaf area redroot pigweed was observed, was not the same among treatments. Light interception by sesame cultivars under redroot pigweed interference decreased by 12, 47, 32, and 42 percent for Oltan, Varamin 2822, Naz Uniculum and Karaj 1, respectively, compared to control. Redroot pigweed interference reduced RUE by 18.6, 35, 27.7, and 21.7 percent for Oltan, Varamin 2822, Naz Uniculum and Karaj1 respectively, compared to control. The highest RUE was observed in Oltan cultivar.