Document Type : scientific research article
Authors
1
Department of Horticultural Science and Engineering, Faculty of Agriculture and Natural Resources, Mohaghegh Ardabili University, Ardabil, Iran
2
Mohaghegh ardabili university
3
Department of Horticultural Sciences, Faculty of Agriculture, Mohaghegh Ardabili University, Ardabil
4
Department of Plant Sciences and Medicinal Plants, Meshgin Shahr Agricultural Faculty, Mohaghegh Ardabili University
Abstract
Abstract
Background and Objectives: Pollution with heavy elements is one of the environmental hazards that has caused a serious challenge in human life. At present, the toxicity caused by cadmium is one of the major environmental problems, because this element is easily absorbed by plants and causes some plants in plants, which causes food consumption. to bring Fertility decreases in plants. Cultivation of sweet pepper in heavy metal-contaminated beds and using contaminated water for its irrigation causes the absorption of these elements and its deposition in plant tissues, especially in the fruit part, and endangers the health of the food chain. Foliar spraying with hormones is one of the solutions that can play a role in reducing the effects of heavy metal toxicity stress in the soil. Melatonin regulates rooting through auxin induction and shoot production through cytokinin enhancement, for this reason melatonin is known as a plant growth regulator.
Materials and Methods: To evaluate the effect of melatonin application on the growth and physiological characteristics of the Clavesol RZ bell pepper cultivar under cadmium stress, a factorial experiment was conducted in a completely randomized design with four replications during the year 2023 in the research greenhouse of Mohaghegh Ardabili University. The experimental factors included the application of cadmium chloride (CdCl2) along with a nutrient solution at three levels (0, 75, and 150 micromoles), and the second factor involved the application of melatonin treatment through foliar spraying at concentrations of 0 (control), 75, and 150 micromolar using a 2-liter hand sprayer. To prevent evaporation and enhance the absorption of melatonin from the plant tissue surfaces, the foliar spraying was conducted early in the morning. The spraying was performed in three stages, with an interval of every 14 days. The first spraying occurred at the 3 to 4 leaf stage after the seedlings were established in the pots. Statistical analysis of the data was performed using SAS 9.1 software. Mean comparisons were conducted using Duncan’s multiple range test at the 1% and 5% probability levels.
Results: The results of the study indicated that increasing cadmium concentration led to a reduction in plant height, leaf area, dry weight of aerial parts and roots, stomatal conductance, and chlorophyll content. In contrast, with the increase in cadmium concentration, the parameters of electrolyte leakage (40.57%), malondialdehyde (32.2%), and proline (65.5%) increased. Additionally, the foliar spraying with melatonin significantly mitigated the effects of stress in stressed plants and increased growth parameters, including leaf area (9.1%), dry weight of the shoot (99.8%), and dry weight of the root (52.9%) in non-stressed plants.
Conclusion: The overall results of the present study indicate that cadmium toxicity leads to disturbances in the growth, physiological, and biochemical characteristics of bell pepper plants. Foliar spraying with melatonin can improve the growth characteristics and performance of bell pepper plants under adverse environmental conditions and abiotic stresses.
Keywords: Growth regulators, growth indices, heavy metals, foliar spraying.
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