Crop productivity and chemical compositions of black cumin essential oil in sole crop and intercropped with soybean under contrasting fertilization

Intercropping systems and the application of organic manures play an important role in increasing of quantity and quality of plant products. In order to evaluate the quantity and quality of black cumin products under contrasting fertilization, a factorial experiment was conducted in a randomized complete block design with three replications in 2016. Soybean and black cumin seeds were sown in five planting patterns (sole black cumin, sole soybean and three intercropping ratios of soybean: black cumin (1:2): one row of soybean plus two rows of black cumin, soybean: black cumin (1:1): one row of soybean plus one row of black cumin and soybean: black cumin (2:1): two rows of soybean plus one row of black cumin. All these cropping systems were received organic manure and chemical fertilizer. The results indicated that the highest seed yield (on an average by 86 g m−2) of black cumin was achieved in sole crop of black cumin treated with organic manure. The maximum seed yield of soybean (on an average by 247 g m−2) and land equivalent ratio (1.06) was obtained in two rows of soybean + one row of black cumin under the application of chemical fertilizer. The p-cymene (20.51–62.77%), carvacrol (2.40–25.99%), longifolene (1.11–24.69%) and spathulenol (0.9–14.45%) were major chemical compositions of black cumin. The highest content of p-cymene and carvacrol of black cumin essential oil were recorded in one row of soybean + two rows of black cumin with the application of chemical fertilizer and one row of soybean + one row of black cumin under chemical fertilizer, respectively. The highest longifolene and spathulenol content was observed in one row of soybean + two rows of black cumin treated with organic manure. These major chemical compositions are useful for industrial use (food and pharmaceutical). Therefore, according to different subjects of applying in industries it could be suggested especial treatment with favorite major compounds.