Study of the effect of the chitosan and chitosan nanoparticles on some physiological and phytochemical features of Nigella sativa L.

Black cumin (Nigella sativa L.) from the Ranunculaceae family is considered one of the best sources of natural antioxidants. Due to the positive effect of chitosan on various medicinal plants, in this study we investigated the vegetative and chemical performance of this plant under the treatment of chitosan nanoparticles. Experimental factors included solubilization of chitosan and its nanoparticles with concentrations of 0.01, 0.05, 0.2, 1, 4 (pH 5) percent. Assays were performed on the seed and leaf extracts of the treated plant at Razi Laboratory of Azad University, Science and Research Branch of Tehran in 2021. Extraction was done by cold pressing method. Some traits such as germination (number, percentage, index and germination rate), growth parameters (radicle and plumule length, fresh radicle and plumule weight and radicle and plumule dry weight), pigments, total leaf phenol content (Folin-Ciocalteau) total leaf flavonoids (aluminum chloride colorimetric assay), leaf antioxidant activity (DPPH), leaf membrane lipid peroxidation (MDA concentration) and soluble protein content Seeds and leaves (Bradford) were evaluated. The experiment was conducted as a completely randomized design with 3 replications and the comparison of data means was performed using Duncan's test at a probability level of 5%. The results showed that the treatment percentages had a significant effect on all evaluated traits (except the fresh weight of the radicle). Treatment of 1% and 0.01% of chitosan nanoparticles increased the growth and germination parameters. In addition, the amount of phenol, flavonoids and antioxidant activity increased compared to the control showed that the highest increase was observed in concentrations of 1% and 0.01% chitosan nanoparticles. The maximum increase in the amount of pigments was due to the concentration of 1% and 0.2% of chitosan nanoparticles. Both treatments at a concentration of 1% reduced the amount of MDA compared to the control. The amount of total protein in leaves and seeds decreased under the influence of the treatments .In general, it was concluded that the treatment of chitosan nanoparticles as a bio stimulant has a positive effect on improving the quality characteristics of black seed and they are also suggested as a suitable stimulus to increase growth.