Document Type : Research Paper
Authors
1 University of Maragheh, Maragheh, Iran
2 Department of production and genetics, faculty of agriculture, university of maragheh
3 3- Soil and Water Research Dept., West Azerbaijan Agricultural and Natural Resources Research and Education Center, Agricultural Research, Education and Extension Organization (AREEO), Urmia
4 Department of Horticulture Science, Faculty of Agriculture, University of Maragheh, Maragheh, Iran
Abstract
Background and objectives: Cultivation of medicinal and aromatic plants has long had a special place in traditional Iranian agricultural systems, and these systems have played an important role in creating diversity and sustainability. Recently, agricultural lands contaminated with heavy metals have attracted much attention due to their destructive effects on agricultural ecosystems. Cadmium (Cd) stress causes changes in various morphological, physiological, biochemical, and molecular processes of plants. This study aimed to investigate the morphophysiological response of grapefruit mint plants to the application of carbon quantum dot nanoparticles (CQD-NPs) and mycorrhiza biofertilizer (AMF) under Cd stress conditions.
Methodology: In order to investigate the effects of carbon quantum dots and mycorrhizal fungi on the morphophysiological characteristics of grapefruit mint plants under Cd stress. A factorial experiment was conducted based on a completely randomized design (CRD) with three replications in the greenhouse of the department of production engineering and plant genetics, Faculty of Agriculture, Maragheh University. The first factor included four Cd concentrations: (0, 10, 20 and 40 mg Cd kg−1 DM soil), the second factor included CQD-NPs levels (0, 5, 10, 20 mg L−1), and the third factor included inoculation and non-inoculation with AMF. In order to conduct the experiment, grapefruit mint rhizomes were cultivated in small pots and transferred to large pots after three months of cultivation. Also, in order to contaminate the soil, cadmium nitrate salt was sprayed between the layers of sieved soil and then grapefruit mint seedlings were planted. In addition, in treatments with biofertilizer, 100 gr of Mycorot biofertilizer was added at the time of planting the seedlings. In the continuation of the experiment, after the plants were fully established in the pots and after three weeks of seedling growth, CQD-NPs were sprayed on the plants at four growth stages. Finally, data analysis was performed using SAS statistical software and means were compared with the LSD test at a probability level of five percent.
Results: The results indicated that with increasing Cd stress intensity, plant height, leaf dry weight, leaf length, leaf number, and chlorophyll index (SPAD) decreased significantly. The highest levels of these traits were also obtained in the non-stress treatment with the application of 20 mg L-1 of carbon quantum dot and mycorrhizal fungi. However, the percentage of essential oil (EO) and antioxidant enzymes of the plant showed an increasing trend with increasing stress. The highest percentage of EO was observed at medium Cd stress level, with the application of 20 mg L-1 of CQD-NPs and AMF. The lowest level of this trait belonged to the severe Cd stress treatment without the use of CQD-NPs and AMF. In addition, the results of this study indicated that the use of CQD-NPs and AMF biofertilizer increased the percentage of grapefruit mint EO by 87% compared to the control. It is worth noting that the chlorophyll index (SPAD) decreased by 52% with increasing Cd stress intensity, even with the combined application of CQD-NPs and AMF biofertilizer. The highest activity of ascorbate peroxidase (APX) and guaiacol peroxidase (GPX) enzymes was obtained at severe cadmium stress levels (40 mg kg−1 soil). The use of CQD-NPs and AMF increased the activity of APX and GPX enzymes by 76.91 and 88.72 percent, respectively, compared to the control.
Conclusion: CQD-NPs and AMF biofertilizer were able to modulate some of the effects of heavy metal stress of Cd by improving the growth of grapefruit mint plants and affect the quality of the EO of this medicinal plant.
Keywords: biofertilizer, carbon quantum dot, essential oil, medicinal plants, Phytoremediation
Keywords
Main Subjects
)