Optimal Nitrogen and LIGHT Regimes to Grow a Medicinal Herb, Calendula Officinalis.

Alongside the use of Calendula officinalis (pot marigold) as an ornamental plant, it also has great pharmacological importance due to the cytotoxic, anti-inflammatory, and antiseptic properties of the flower extract. However, very little has been understood about the optimal indoor growth requirements of the plant. The aim of the project is to evaluate the responses of vegetative growth and flower production of Calendula under the interaction of differential nitrogen fertilizer and light intensity. Four treatments were imposed to grow Calendula plants in the greenhouse: 1) 100% light with nitrogen (in the form of 0.1 M ammonium nitrate); 2) 100% light without nitrogen; 3) 50% light with nitrogen; and 4) 50% light without nitrogen. Significant difference in vegetative growth was observed between plants treated with nitrogen under 100% light and 50% light, as shown by the height of the plant, the number of leaves, and the chlorophyll content in the leaves. Moreover, a higher number of flowers were produced on Calendula plants grown under 50% light without nitrogen. Currently we are analyzing frozen leaf, stem and flower samples with an aim to understand the molecular basis for above-mentioned morphological and physiological variations through differential gene expression analysis using qPCR. A repeated cycle of the treatments and measurements is also undergoing in the greenhouse to verify the findings and to collect more samples for further analysis.