Effect of Organic, Biological and Chemical Fertilizers on Yield, Yield Components and Oil Yield of Black Seed (Nigella sativa L.)

 In recent decades, agricultural production has largely relied on the use of chemical inputs, which has led to major environmental problems. Destruction of water and soil resources, deterioration of agricultural biodiversity, air and water pollution by chemical fertilizers and pesticides are only part of the environmental problems caused by common agricultural use of chemical inputs. One of the solutions to this problem is to apply sustainable farming principles in agricultural ecosystems. Soil management is one of the main factors in achieving sustainable agriculture. Therefore, the gradual replacement of chemical fertilizers with organic and biofertilizers will help to meet the nutritional needs of plants, improve the physical, chemical and biological conditions of the soil and prevent the adverse environmental effects of chemical applications. Organic matter has been recognized as one of the nutrients of plant nutrition and fertility due to its constitutive effects on soil physiological and biological properties. Organic fertilizers are the most important source of organic matter in the rhizosphere of plants. Black seed is an annual, dicotyledonous, herbaceous, medicinal plant belonging to the Ranunculaceae family. Environmental conditions and soil fertility are one of the factors affecting grain yield, quantity and quality of essential oil and oil produced in black seed. Since there is not much research on the effect of humic acid and fulvic acid on black seed, therefore, attention to the management of nutritional needs of black seed with emphasis on the use of biological and organic fertilizers in the successful cultivation of this plant is inevitable.

In order to evaluate the effects of organic, biological and chemical fertilizers on yield, yield components and oil yield of black seed, a field experiment was conducted at Research Station, Faculty of Agriculture, Ferdowsi University of Mashhad, Iran, during the growing season of 2011-2012. The experimental layout was factorial based on randomized complete block design with three replications. Experimental treatments included all combinations of organic and biological fertilizers factor in four levels (biosulfure + 100 kg.ha-1 sulphor, humic acid (7 kg.ha-1), fulvic acid (7 kg.ha-1) and control) and chemical and animal manure factor in three levels (chemical fertilizer (NPK (80:40:30 kg.ha-1, respectively), animal manure (20 t.ha-1) and control). In order to determine the oil content, 5 grams of grain were randomly selected from the grains harvested from each plot and then oil content was determined by Soxhlet. Analysis of variance (ANOVA) and regression analysis of the data from the experiment and drawing of shapes were performed using SAS and MSTAT software's. Comparisons of means were performed at 1 and 5% probability level using Duncan multiple range test.

The Results showed that studied factors and their interactions had significant effect on number of seed per plant, seed weight/plant, seed yield and oil yield. The highest plant height, number of branch per plant, number of follicles per plant, number of seeds per follicles , number of seeds per plant, seed weight per plant, seed yield and oil yield (59 cm, 5.8,7.8,72, 594,1.075g, 2.2 (t.ha-1), 517 (kg.ha-1), respectively) were observed in chemical fertilizer + biosulfur biofertilizer treatment and  the lowest mentioned traits (49 cm, 3.01, 3.92, 39.8, 194, 0.445, 0.935 (t.ha-1), 221 (kg.ha-1) respectively) were observed in control treatment. The highest and lowest harvest indexes were observed in animal fertilizer + humic acid (49%) and control (25.6%) treatments, respectively. The highest and lowest oil percentages were observed in animal fertilizer + humic acid (49%) and control (25.6%) treatments, respectively. The results indicated that the use of humic and fulvic acids, and biosulfur biofertilizer alone or in combination with chemical fertilizers and animal manure improve the quantity and quality of Nigella sativa characteristics.

The results of this study revealed that considering the positive response of the black seed to application of organic and biological fertilizers, applying these fertilizers while reducing the use of chemical fertilizers as well as having no adverse environmental effects is an appropriate method for sustainable production and environmental protection.