عنوان مقاله [English]
Introduction: Selenium is a non-metallic, rare chemical element and essential for many organisms but this element is not mentioned as an essential element for plants. Due to its presence in antioxidant defense systems and hormonal balance, selenium is known to be necessary in human and animal health Plants exhibit a variety of physiological responses to selenium.Some species accumulate large amount of selenium, while many plant species are sensitive to presence of large amounts of selenium in soil and water. The mean, the maximum and tolerance level of selenium required for humans is 45, 55 and 400 micrograms, respectively (Dietary Reference). but acute toxicity level in animals are found with a concentration of 1000 ppm. Plants absorb and storage selenium in chemical form and concentration depends on pH, salinity and calcium carbonate content. High contents of selenium reduce plant growth and plant dryness, however in some plants low selenium concentrations improved growth and increase stress resistance by maintenance of chloroplast enzymes. Positive response to the use of selenium were mentioned in lettuce, potato, mustard, crap, darnel, soybean (Glycinemax L), potatoes and green tea leaves. Research has shown that there is a positive relationship between selenium concentration and glutathione peroxidase activity, which is a reason to delay aging and increase growth of aging plants. The results of this study had shown that the application of selenium treatments increased leaf area of plants and, consequently, the higher availability of asmilates, can increase plant growth. The results of the studies also indicated that all vegetative characteristics of plants are increased due to the concentration of selenium and the accumulation capacity of plants affected by selenium application. Since there is no research on the effect of selenium on cabbage, it seems that the use of this element can affect the growth and development of this plant.
Materials and Methods: This experiment was tested in a controlled condition hydroponic greenhouse of Horticulture Department, College of Agriculture, University of Tabriz, The greenhouse was covered with polyethylene monolayer and equipped with a cooling and fogging systems to control the temperature in the warm months and humidity, respectively. Daily temperatures were setted3 ± 20 3 ± 16. Seeds of Gemmifera varieties brussels cabbage weregerminated in petri dishes. Seedlings were transferred to the plastic cups (to the floating system) with perlite in four leaf stage. . Plants root system were floated in solution. Modified Hoagland nutrient solution (Table 1) was prepared (12 liters per container with 40 and 32 cm height and diameter, respectively.
Results and Discussion: Results of vegetative Brussels sprouts button showed that selenium significantly increased leaf, stem and root dry weight, leaf number and leaf area. Leaf area, leaves, stems and roots fresh and dry weight increased with increasing selenium up to 8 mg L- but then decreased due to a high concentration of selenium toxicity. There were no significant difference in the treatments on stem length, stem diameter. Number of buds was significantly (P≤0.05) affected by selenium treatments and the highest number of sprouts were in two levels of 8 and 16 mg selenium per liter, respectively. Yield and shoot dry weight showed a significant increase (at 1 percent) with increasing levels of selenium,.Conclusions Plants yield significantly (P≤0.01) affected by selenium treatments, so that selenium concentration in the nutrient solution increased from 0 to 8 mg L-1increased yield and reduced afterward. The maximum yield was observed at a concentration of 8 mg L-compared with control. Based on the findings of this study, selenium concentration can be up to 8 mg L-1 in order to improve plant growth to nutrient solution.