Effects of biofertilizers and foliar application of nano iron oxide on quantitative and qualitative yiled of black Cumin (Nigella sativa L.)

In order to study the effects of nano iron oxide and different biofertilizers on the quantitative and qualitative yield of black cumin (Nigella sativa L.), a factorial experiment based on randomized complete block design with three replications was conducted in the research field of Shahrood Industrial University in 2017 growing season. Experimental treatments included the foliar spray of nano iron oxide at three levels of 0, 1.5 and 3 g L-1 as the first factor and five levels of biofertilizer including no biofertilizer (control), Glomus intraradices, G. mosseae, Azospirillum, and Azotobacter as the second factor. The results of this experiment showed that the application of fungal and bacterial treatments significantly increased the grain yield and yield components as well as the concentration of nitrogen and iron in seed, and also had a significant effect on increasing essential oil content, thymoquinone content of the essential oil, and seed oil. The most effective treatment was G. intraradices, which was able to significantly improve all traits measured. The foliar application of nano iron oxide had a significant and positive effect only on the essential oil content, biological yield, and iron and nitrogen content of the seed. The highest amount of iron and nitrogen content of the seed was obtained in nano iron oxide treatment at 3 g L-1 level. However, the essential oil content, essential oil thymoquinone percentage, seed oil content, and also biological yield did not differ significantly between the two concentrations of nano iron oxide. Therefore, it seems that the application of a lower concentration of nano iron oxide (1.5 g L-1) together with G. intraradices can improve the quantitative and qualitative yield in the medicinal plant black cumin by saving fertilizer consumption without a significant decrease in the qualitative traits measured.