عنوان مقاله [English]
Background and Objectives: Oil seeds are important sources of vegetable oils. Safflower seed with 25-45% oil is one of the valuable oil seeds. Nowadays, people are aware of chemical fertilizers harmful effects on the environment. So the application of organic amendments is known as a suitable strategy to increase soil organic matter. One of the methods for utilization of aquatic waste is using them as an organic fertilizer. It is full of nutrients especially nitrogen and phosphorous that can eliminate their deficit in farms and gardens. Chitin found in the exoskeleton of shrimp is the second most ubiquitous natural nitrogenous polysaccharide after cellulose on earth. Huge amounts of fish wastes and shrimp have been abandoned by worldwide seafood companies. So using these renewable waste materials as fertilizer is economically feasible. Since nitrogen and phosphorus are essential elements in safflower growth, applying fish wastes and shrimp which are rich in these elements can improve the quantitative and qualitative characteristics of safflower.
Materials and Methods: In order to investigate the effect of shrimp and fish wastes on safflower, an experiment was conducted in completely randomized design with 13 treatments (3 gr shrimp at the soil surface, 3 gr shrimp mixed with soil, 1.5 gr shrimp at soil surface, 1.5 gr shrimp mixed with soil, 3 gr shrimp + 0.2 gr urea at soil surface, 3 gr shrimp + 0.2 gr urea mixed with soil, 1.5 gr shrimp + 0.2 gr urea at soil surface, 1.5 gr shrimp + 0.2 gr urea mixed with soil, 5 gr fish at soil surface, 5 gr fish mixed with soil, 10 gr fish at soil surface, 10 gr fish mixed with soil, and control) and 4 replications in the University of Nahavand. Number of seed, head diameter, number of flowers per plant, number of branches per plant, 1000- grain weight, oil percentage fatty acid content and type were measured.
Results: The results represent the positive effect of shrimp and fish wastes on the studied traits so that the most head diameter (2.1 cm) was observed in the 1.5 gr shrimp at the soil surface treatment, the most seed number by application of 1.5 gr shrimp mixed with the soil, and the highest amount of 1000-grain weight (39.1 gr) in the treatment of 5 gr fish mixed with the soil. The most oil percentage (25.31%) was produced in 3 gr shrimp + 0.2 gr urea mixed with the soil. The most linoleic acid (73.56%) was produced with using 3 gr shrimp + 0.2 gr urea at soil surface and the most oleic acid (33.22%) and linolenic acid (0.38%) belonged to 1.5 gr shrimp + 0.2 gr urea at soil surface treatment. The highest amount of palmitic acid (11.32%) was created in 3 gr shrimp mixed with the soil and the most content of stearic acid (1.97%) in 10 gr fish at the soil surface treatment.
Conclusion: The results showed the positive effect of fish and shrimp wastes especially shrimp, on all of the studied traits. Also, with the simultaneous application of organic and chemical fertilizers, the highest percentage of oil was produced. Considering the results of this study and in order to reduce the use of chemical fertilizers and to achieve sustainable agriculture purposes, we can use abundant fish and shrimp wastes as either an alternative or a complement for chemical fertilizers. Due to abundant sources of fish and shrimp waste in the south of Iran and high resistance of safflower to drought and salinity stress, use of aquatic waste as a fertilizer in safflower cultivation can be the subject of future researches.