The effect of seed pre-treatment on some quantitative, biochemical traits and oil percentage of Black cumin (Nigella sativa L.)

Background and objectives: Today, medicinal plants have received a lot of attention in the scientific and medical communities. Black cumin (Nigella sativa L.) is the most important species belonging to the Ranunculaceae family. In the cultivation of medicinal and aromatic plants, various problems occur in the germination of the seeds of some plants. Due to the insufficient growth of the embryos, the black seeds have sleeping characteristics, which causes the non-uniform growth of the seedlings. Since in agriculture, seed germination is considered very important to obtain lively plants and high yields, there is a need for a process that facilitates germination. A process described as seed priming or pre-treatment. For this purpose, this experiment was designed and implemented to investigate the effect of different seed pre-treatments on some quantitative and qualitative traits of black seed in the climatic conditions of Gorgan.
Materials and methods: This experiment was carried out in the form of a randomized complete block design in three replications at the Agricultural and Natural Resources Research and Education Center of Golestan Province in the crop year 2021-2022. The experimental treatments include nine different pre-treatments, such as fertile phosphate, Phosphorus-Zinc (containing 10% phosphorus and 10% zinc), Trichoderma fungus (Bioran company), zinc (zinc sulfate), mycorrhizal fungus (Funneliformis mosseae species), Bioazospire (containing Azotobacter sp., Azospirillum and Bacillus), Molybdenum (ammonium molybdate), humic acid (46% ligno-humex) and control. The amount of seed used in this research was considered to be 2.5 grams per plot based on the weight of 1,000 seeds and optimal density (100 plants per square meter). The used seed (an Indian variety) was prepared at the Agricultural and Natural Resources Research and Education Center of Golestan Province. In this experiment, traits such as the height of the plant, the height of the first branch, the root length, the total weight of the plant, the weight of the capsule in the plant, the number of follicles in the capsule, the weight of the seeds in the capsule, the total weight of the seeds in the plant, the percentage of oil, total phenol, Flavonoids, and antioxidants were measured. Finally, the statistical analysis of the data was calculated using SAS statistical software, and the average comparison of the data was calculated using the LSD test at the probability level of one percent.
Result: The results of this research showed that seed pre-treatment significantly affected all studied traits except the number of follicles. The comparison of the average traits showed that the maximum height, with an average of 77.22 cm, was observed in plants treated with molybdenum. The maximum height of the first secondary branch (15.16 cm) and the highest amount of antioxidants (66.19 mg/g) were assigned to pre-treatment with mycorrhizal fungi. The highest weight of the total plant (17 grams), the maximum weight of the capsule in the total plant (8.37 grams), the highest weight of the seeds in the capsule (0.22 g), and the maximum weight of the total seeds in the plant (6.10 grams) in fertilizer pre-treatment Bioazospire were observed. Also, in this research, the maximum root length (14.44 cm), the highest oil percentage (27.99%), the highest amount of total phenol (22.53 mg/g), and the maximum amount of flavonoid (9.33 mg/g) were obtained from pre-treatment with humic acid.
Conclusion: The results of this study indicated a significant effect of seed pre-treatment on all studied traits. Among these pre-treatments, Bioazospire, humic acid, mycorrhiza, and molybdenum improved vegetative and functional traits. In general, based on the results of this research, if the aim is to increase seed yield or oil percentage, bioazospire and humic acid can be used as seed pre-treatments, respectively.