Marigold (Calendula officinalis) yield as affected by lamb's-quarters (Chenopodium album) competition

Abstract

To study interferential effect of lamb's-quarters (<em>Chenopodium album </em>L.) on <br />marigold (<em>Calendula officinalis</em>) yield and lamb's-quarters seed production two <br />factorial field experiments were conducted in Tabriz, Iran, during 2010-2011. <br />Treatments were densities of lamb's-quarters (0, 2, 4, 6 and 8 plants per meter row) <br />and relative times of its emergence (0, 10, 20, 30 and 40 days after marigold <br />emergence). Marigold could tolerate4 lamb's-quarters plants per meter row without <br />any significant yield reduction, when it emerges 40 days after that of marigold. A <br />suitable fit to model of Cousens et al. was obtained for all marigold flower yield <br />data sets at interference with lamb's-quarters. Results also indicate that controlling <br />lamb's-quarters early in the season may reduce its seed production capacity.