Effects of sowing date, plant density and nitrogen fertilizer on yield, yield components and various traits of Calendula officinalis.

In order to investigate the effect of different levels of sowing dates, plant density and nitrogen fertilizer on different growth and productive variables of Calendula officinalis, an experiment was conducted using split plot factorial on the basis of randomized complete block design with three replications in Zaheden region during 2008-2009. Main plots were consisted of sowing date in 3 levels, 1 ,15 and 30 of April and sub th th th branches length, length and width of leaves, peduncle length, auxiliary stem diameter, main stem diameter, flower diameter, wet flower weight, dry flower weight, number of flower, number of petal, Leaflet length, leaf number, plant weight, stem and root weight and amount of essence. The result of main effects of compound variance analysis including of year, sowing date, plant density and nitrogen fertilizer showed that sowing date on April 1 , (12 ×50) plant density and 50 kg ha of nitrogen fertilizer, had the most effect in increasing the st 1 traits. Also, interaction effects of date × year, date × density, date × N fertilizer, date × density × fertilizer, date × density × N fertilizer × year, year × density, year × N fertilizer, density × N fertilizer × year, density × N fertilizer were significant at 5% probability level in all traits. In general, the result of study demonstrated that using of suitable sowing date together with density and amount of nitrogen fertilizer increase yield, yield components and essence of calendula.