Effect of different irrigation levels on yield, quality and phenology of black cumin (Nigella sativa L.)

The knowledge about certain herbs with curative and alleviative effects on disease conditions has been transmitted from one generation to another in every culture throughout history. Nigella sativa, also known as black cumin, is one of those medicinal plants, its seeds show a wide therapeutic potential, and they are used as spice in different kind of foods. Despite the enormous potential of this plant limited information about its cultivation and production is available. Under the current climatic conditions water management comes to be particularly relevant, it is necessary to reduce the water consumption and make a more efficient use of it. The present work had two objectives, firstly to evaluate the effect of different irrigation levels on yield and quality of black cumin seeds, and secondly to characterize the phenology of the plant. The experiment was carried out in the experimental field of the Field Crops Department of Çukurova University. The trial was arranged based on a Randomized Complete Block design, with five treatments and four replications. Treatments were arranged as follows: receiving 0%, 10%, 50%, 70% and 100% of the crop´s water requirements. The irrigation regimes were applied over the Seed Maturation stage. As result of the experiment, the phenology of Nigella sativa L. under Mediterranean conditions was characterized, the life cycle was completed in 224 days. Concerning the irrigation levels, the highest seed yield belonged to the 50% IR treatment (1199 kg/ha). The 0% IR- treatment produced the highest essential oil yield (0.69%). The major compounds of the essential oil varied from treatment to treatment. The compound farnesol was found in concentrations never before seen in amounts ranging from 3.04% to 20.79%. The highest fixed oil content belonged to the 50% IR-treatment with 36.33%. The major fatty acids composing black cumin seeds were linoleic acid and oleic acid, the average values being 60.08% and 20.52% respectively. Based on the results, it can be concluded that deficit irrigation is a valuable strategy to manage the water resource in Nigella sativa crop.