Effect of nitrogen fertilizers on agronomic, essential and enzymatic properties of marigold (Calendula officinalis L.) under normal and drought conditions

Abstract

To investigate the effect of mineral and organic nitrogen fertilizers on some of the quantitative and qualitative reactions of marigold under normal and drought stress, a study was conducted in a split-plot factorial and based on a completely randomized block design with three replications. The first factor included irrigation (normal and water deficit) in the main plot and sub-factor included foliar application of nitrogen fertilizer (control, nitrogen (N), nano-chelate nitrogen (NC) and nitrogen fertilizer+ nano-nitrogen fertilizer (N+NC)) and biofertilizer (control, Azotobacter and Azospirillum) as factorial was placed in sub-plots. Although water deficit stress reduced plant height, flower dry weight, number of seeds per head, 1000-grain weight, biological yield, grain yield and essential oil yield, N + NC foliar application could moderate the adverse effect of water stress on the grain yield, biological yield and essential oil yield. In addition, inoculation of seeds with Azospirillum under water stress conditions could increase the number of seeds per head, 1000-grain weight and essential oil yield compared to the control treatment. NC foliar application and Azotobacter inoculation showed a synergistic effect on the content of proline enzymes and antioxidant activity. Also, simultaneous application of nitrogen + nano-chelate nitrogen foliar application along with seed inoculation with Azospirillum could have a positive effect on increasing flower dry weight, the number of seeds per head, 1000-seed weight, biological yield, grain yield, essential oil yield and proline content.