Document Type : Research Paper
Authors
1 Sana Institute of Higher Education
2 Islamic Azad University of Qaemshahr Branch
3 Range and Watershed Management, Faculty of Natural Resources, Isfahan University of Technology
Abstract
Background and objectives: Nowadays, due to the revelation of the harmful effects of chemical drugs for most users, the desire to use medicinal plants has increased significantly. Basil (Ocimum basilicum L.) is one of the most important medicinal plants of great interest in various pharmaceutical industries due to its valuable and vital secondary metabolites, such as essential oil. However, salinity is considered a major constraint for its productivity. Soil and irrigation water salinity is a major constraint for crop production. In salinity-rich soils, the osmotic pressure increases, and the plant must burn more vital energy to absorb water. Increasing the salinity tolerance of plants for sustainable food production, especially in arid and semi-arid regions, can reduce the need for irrigation and, thus, production costs. Since using calcium nanoparticles increases nutrient utilization efficiency, reducing soil toxicity, minimizing the adverse effects of over-fertilization and reducing the frequency of fertilizer application, the present study investigates the effect of calcium nanoparticles on physiologic and biochemical properties of basil medicinal plant under salinity stress.
Materials and Methods: The plants were treated with calcium nanoparticles in five levels by spraying with concentrations of 0, 0.25, 0.5, 1 and 1.5 g/l and salt concentrations of 0.75 and 150 mM along with Hoagland solution in a completely randomized design in a greenhouse environment with three replications. Some growth characteristics such as height, number of leaves, leaf area, fresh and dry weight, amount of chlorophyll a, chlorophyll b, total chlorophyll and carotenoid content of the plant were measured. Some biochemical characteristics such as flavonoid, soluble sugar, anthocyanin content and antioxidant enzymes such as catalase and peroxidase were also measured. The least significant difference (LST) test was used to compare the means in SAS software.
Results: The results of ANOVA showed a significant effect of calcium nanoparticles on most morphological traits. Also, different salinity levels alone significantly affected the studied traits (p<0.01). Following the reduction of the osmotic potential of the soil solution due to salinity stress, water absorption decreases and as a result of stomata closing, the photosynthesis and respiration decrease. The mean comparison of the simple effect of calcium nanoparticles on chlorophyll pigments showed that with increasing the nanoparticle level, chlorophyll content increased, and as a result, photosynthesis improved. The simple effect of different salinity levels on some traits (phenol, soluble sugar, peroxidase enzyme and anthocyanin) showed that increasing the salinity level caused an increase in these traits. So, at the concentration of 150 mM salinity, phenol content with 8.02 mg of gallic acid per g of dry weight showed the highest amount compared to the control sample of 10.5 mg. Also, the soluble sugar content was the highest at this salinity concentration, with 139.9 mg/g dry weight, compared to the control, with 110.9 mg/g dry weight. The interaction effect of calcium nanoparticles and salinity on basil's morphological characteristics and carotenoid content was insignificant. However, it was significant in the chlorophyll content, the amount of flavonoids and catalase (p<0.01). In fact, with nano fertilizers, the plant can absorb more nutrients, and while reducing the leaching of elements, the yield of the product increases.
Conclusion: The results of this study suggest that the physiological and biochemical characteristics of Basil were affected by salinity stress, and the interaction of nano calcium with salinity stress reduced the effects of salinity stress. Therefore, spraying the nano-fertilizer in an appropriate concentration is suggested to improve the yield of basil in salinity stress conditions.
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