Abstract

Pot marigold (Calendula officinalis L.) is a medicinal and ornamental plant. In an experiment which was designed in factorial on the basis of completely randomized block design with 3 replicates in 36 plots. The effects of plant density (20, 40, 60 and 80 plants/m²- factor A) and sowing date (April 19 and 29, and May 10, 2010- factor B) were evaluated on the growth, flowering and essential oil of C. officinalis L. Studies were carried out on experimental field in Islamic Azad University, Rasht, Iran. Investigated characteristics were: plant dry weight, flower number/plant, branch number/plant, flower dry weight, flower yield/area unit, and quantity of essential oil. Maximum of plant dry weight (35.67 g), flower number/plant (25.88), branch number/plant (9.44), flower dry weight (3.72 g), and amount of essential oil/100 g dried flower (0.16 ml) were obtained at the 20 plants/m², while maximum of flower dry weight (132.07 g), and amount of essential oil (0.19 ml), both per area unit were obtained at the 60 plants/m². The effect of sowing date for all characteristics was not significant. Interaction between plant density and sowing date was significant for all characteristics and the best treatments were the 20 plants/m² on 19 and 29 April.

Key words: Dry weight, flower production, pot marigold, Iran.