Improving the productivity and quality of black cumin (Nigella sativa L.) by using soil fertility management practices

Abstract

One of the most important plants containing volatile and fixed oil is black cumin family Ranunculaceae is an herbaceous indigenous plant in the Mediterranean region. Seeds of this plant have been used for centuries as a spice and food preservative, as well as a traditional medicine for the treatment of various diseases. A split-plot experiment using a randomized complete block design with three replications was performed in the crop years 2017–18 to analyze the effects of soil fertility management practices on essential oil and seed oil properties of medicinal plant black cumin (Nigella sativa L.). The two crop years were the first factor (the main plots) and the various soil fertility management practices were the second factor (the subplots). The fertility management treatments were various application rates of the chemical fertilizers, manure, combination of chemical–manure and chemical–manure–Azorhizobium. The results showed that combination of chemical–manure–Azorhizobium increased the plant yield components in the first year and second year. In the second year, some physiological characteristics were increased. Dry weight, seed yield, biological yield, percentages of seed oil and essential oil increased with the application of the chemical–manure–Azorhizobium. The combined application of manure at 30 t/ha together with Azorhizobium had the greatest positive effects on the improvement of vegetative and reproductive characteristics of black cumin. Low application of chemical fertilizers had a little effect on the plant characteristics. These results show that the integrated plant nutrition management (IPNM) reduced chemical fertilizer (NPK) application rates; thus, it was a step to sustainable agriculture and reduction of environmental impacts.