| Abstrakt: |
Background and Objectives: Chromium (Cr) is a toxic metal usually found in many regions and countries, because of excessive discharge of Cr-containing effluents resulting from industrial and agricultural activities. In higher plants, Cr is not essential to plant growth. Exposure to Cr may cause tissue necrosis and limit chlorophyll production. In particular, it is usually involved in electron transfer and induce production of reactive oxygen species (ROS) e.g., hydroxyl radicals and superoxide radicals, resulting in oxidative stresses and damages to plant cells and tissues. Symbiosis fungi significantly accelerate plant growth by improving water and nutrient uptake, early flowering, seed production and greater photosynthetic rate. These fungi change the production of secondary metabolites and enhance adaptation and tolerance to biotic and abiotic stresses. This study aimed to investigate the role of mycorrhizal and endophytic fungi (Glomus intradises and P. indica) as possible tools to reduce the phytotoxicity of Cr. Materials and Methods: In order to evaluate the effect of different concentrations of Cr (0, 3 and 15 mg L-1 ), and symbiotic fungi on growth and physiological properties of lettuce (Lactuca sativa cv. Little Jem), an experiment was carried out as factorial split plot based on Completely randomized design with four replications as soilless system at research greenhouse of University of Mohaghegh Ardabili, in 2021. In this experiment Cr and nitrogen content, root colonization, root and shoot dry weight, leaf number, stem and leaf dry and fresh weight, chlorophyll and carotenoid content, stomatal conductance, electrolyte leakage, ascorbate peroxidase and catalase activities, hydrogen peroxide and were measured. Results: The results showed that by increasing the concentration of Cr from 0 to 15 mg L -1 in the nutrient solution, the root symbiosis percentage decreased by 20%, root dry weight by 11.7%, shoot dry weight by 12.9% and soluble protein by 10.3%. The symbiosis of lettuce roots with symbiotic fungi significantly increased root and shoot dry weight, leaf number and soluble protein compared to non-inoculated plants. Plants inoculated with symbiotic fungi P. indica and G. intradises were able to reduce the negative effects of Cr toxicity by reducing Cr absorption and increasing the percentage of symbiosis, nitrogen content, chlorophyll content, ascorbate peroxidase activity and hydrogen peroxide. Conclusion: The results show that with increasing the concentration of Cr in the nutrient solution, lettuce growth decreased and the use of symbiotic fungi could improve the physiological and biochemical characteristics of lettuce under Cr stress. [ABSTRACT FROM AUTHOR] |
