Introduction: Producing oil from plant sources such as oil crops and obtaining a high level of oil from them is influenced by many factors, among which the physical and chemical properties of the soil are of great importance. For this purpose, the recommendation to use the optimal amount of fertilizers to achieve the highest yield should be considered. Camelina sativa has attracted the attention of many researchers, especially in semi-arid regions, due to its adaptive characteristics such as tolerance to cold and drought stress. It has been reported that camelina can survive temperatures below -11°C and can also be grown in areas with moderate rainfall throughout the growing season. Plastic mulch (polyethylene, PE), which has been a favorite of many producers in the past decades, is among the agronomic practices through which moisture is conserved for use during the expected dry season.
Material and methods: This study was conducted in two counties located in Kermanshah province (County 1: Kermanshah and County 2: Kangavar); a split-plot experimental design was used. The cumulative rainfall during the growing season was 476.5 mm in County 1 and 343.6 mm in County 2. The planting date in the fall was determined based on surveys so that the plants would escape the heat of the end of the growing season. Camelina seeds were planted after performing a germination test, resulting in a germination percentage of 89%. In order to find the optimal rate of nitrogen fertilizer utilization, four levels of nitrogen input (urea), including 0, 40, 80, and 120 kilograms per hectare, were applied (F_1, F_2, F_3, F₄). To find the best way of applying plastic mulch for camelina cropping, three levels of polyethylene plastic mulch (PE), including no PE, PE on the plants, and PE on the soil surface, were surveyed (M₁, M₂, M₃). Nitrogen was applied in three phenological stages, including 4 leaves appearing, the beginning of stem growth, and the beginning of the reproductive stage. In this research, transparent polyethylene plastic with a UV grade of 10 and a thickness of 40 microns was used. Some morphophysiological aspects of camelina growth were evaluated, including: plant height, stem diameter, number of leaves, leaf area index (LAI), leaf area duration (LAD), number of lateral shoots, yield components, and seed yield. Sampling for evaluating the morphological properties of camelina was conducted when 50% of the panicles appeared. 
Results and Discussion: The results of this study indicated that using plastic mulch and applying an optimal rate of nitrogen fertilizers can be useful to achieve satisfying values of production in camelina cropping systems. The highest plant height was recorded when using PE mulch on the soil with applying 120 kilograms of nitrogen per hectare (118.2 cm), while the lowest plant height was recorded when no PE and no nitrogen was used (control treatment). Applying 80 and 120 kilograms per hectare of nitrogen enhanced the stem diameter significantly. The highest leaf area index was recorded using 120 kg/ha of nitrogen and polyethylene mulch at the soil surface (4.03). The leaf area index was significantly lower in conditions where there was no nitrogen and polyethylene mulching treatment (control treatment). Minimum seed yield was recorded under the control treatment (68 gr/m²), and the maximum value was recorded when using PE mulch on the soil surface and applying 120 kg/ha nitrogen input.
Conclusion: The overall results of this study indicate that to achieve the highest seed yield of C. sativa in climatic conditions such as the two counties in this study, the use of nitrogen fertilizer at a rate of 120 kg/ha with the use of polyethylene mulch on the soil surface is recommended.