Effect of different levels of nitrogen fertilizer on vegetative and reproductive
growth
of marigold (Calendula officinalis L.)

In order to study the effects of different levels of nitrogen fertilizer on vegetative and reproductive
yield of marigold, an experiment was conducted as a randomized complete block design with three replications at the Medicinal Plants Research Station of Semnan. Treatments consisted of four levels of ammonium nitrate fertilizer including 0 (control), 100, 200 and 400 kg.ha-1 that were applied in three stages of plant growth. Measured traits included dry and fresh weight of aerial parts, dry and fresh weight of stem, dry and fresh weight of leaf, plant height, coverage crown diameter, flower diameter and dry and fresh weight of flower. Based on the results, the effects of ammonium nitrate fertilizer was significant on all the studied traits, except plant height and dry wight of aerial parts.
Fertilizer application increased vegetative and reproductive traits of marigold. Maximum flower dry weight was obtained by applying 400 kg.ha-1 ammonium nitrate fertilizer. Because flowers of marigold is econnomic part of this plant, application of 400 kg.ha-1 ammonium nitrate fertilizer was recommended in order to obtain maximum dry weight of marigold flower