Evaluation of vermicompost application and amino acid spraying on yield and essential oil of black cumin (Nigelle sativa L.)

Intensive cultivation has led to a rapid decline in organic matter and nutrient levels besides affecting the physical properties of soil. The sustainability of production systems has become an important issue throughout the world. Black cumin (Nigella sativa L.) is one of the most widely used medicinal and industrial plants. Furthermore, today, using organic and biofertilizers as a tool to achieve sustainable agriculture was considered. The current study was conducted as a factorial experiment at the Forest and Rangeland Research Institute of Iran in 2019 as a randomized complete block design with three replications. The treatments included six vermicompost levels (0, 3, 6, 9, 12, and 15 tons ha-1), and the foliar application of amino acid at 3 levels (no foliar application, foliar application at the beginning of the flowering stage and foliar application at the beginning of the encapsulation stage). The results of the study showed that amino acids, vermicompost, and their interaction had a significant effect on leaf yield. Moreover, the interaction of amino acid × vermicompost significantly affected biological yield and essential oil yield. Comparing the mean oil yield showed that the highest oil yield (73.22 kg ha-1) was related to the 6 tons of vermicompost × no foliar application of amino acids. The results showed that using vermicompost and amino acids could increase the quantity and quality of Nigella sativa L. in sustainable cropping systems.