جستجوی مقالات مرتبط با کلیدواژه "selenium" در نشریات گروه "باغبانی"

Selenium is one of the useful chemical elements for plants growth which, in addition to its beneficial effects on plant growth, is known as an essential substance for human and animal health. This research was carried out to investigate the effect of different levels of sodium selenate and selenite on some growth and physiological traits of peppermint in a completely randomized design with 4 replications. Plants were grown in a soilless culture system in the research greenhouse of the faculty of agriculture, Ferdowsi University of Mashhad, The treatments included different levels of sodium selenate (4, 8 and 12 mg/L) and sodium selenite (4, 8 and 12 mg/L), equal to 0.02, 0.04 and 0.06 M of selenate and selenite sodium, respectively in Hoagland solution. The control treatment was a Hoagland solution without selenium application. Based on the results of the analysis of variance, the effect of sodium selenate and sodium selenite on all measured traits was significant. The results showed that the highest dry weight of aerial parts was observed in the treatment with 4 mg/L of sodium selenate. The relative water content of the leaf (6.6%) and guaiacol peroxidase activity (29.02%) were increased with the treatment of 4 mg/L of sodium selenate, compared to the control. The treatment with 12 mg/L of selenite and selenate sodium increased the ion leakage percentage, malondialdehyde and hydrogen peroxide concentrations. According to the obtained results, the treatment of 4 mg/L of selenate and selenite sodium is recommended to increase growth and improve some physiological characteristics in peppermint plant.

To investigate the effect of sodium selenate (Na2SeO4) and sodium selenite (Na2SeO3) on some morphological characteristics and nutrients concentration in peppermint, an experiment was conducted in a completely randomized design with four replications. Different levels of sodium selenate and sodium selenite (0, 4, 8, and 12 mg l-1) were applied in soilless cultivation in the research greenhouse of the Faculty of Agriculture, Ferdowsi University of Mashhad. Then morphological traits and the concentrations of nutrients in the leaf were measured in the flowering stage. The results showed that the application of two forms of selenium at a concentration of 4 mg l-1 increased the growth traits in peppermint. The highest concentration of both salts decreased the plant growth. The results also showed that with increasing the concentration of selenite and sodium selenate, the selenium concentration increased, but the use of sodium selenate caused higher concentration of this element in the leaf. At a concentration of 4 mg l-1 selenium, the concentrations of macronutrients including nitrogen, phosphorus, potassium, calcium, and magnesium in the leaf increased by 43.7, 11.1, 3.2, 11.6, and 9.2%, respectively, compared to the control but were not significant. The highest nitrogen concentration was observed at the concentration of 4 mg l-1 sodium selenite 43.7% greater than the control. With increasing the concentration of selenium, except for molybdenum and manganese, the concentration of zinc, iron, boron, and copper increased. The highest concentrations of iron and boron were obtained at 12 mg l-1 sodium selenate, 60.2 and 25.7% greater compared to the control, respectively. The highest concentrations of zinc and copper measured at 12 mg l-1 sodium selenite were 63.3 and 40.6% greater than the control, respectively. In general, it is concluded that 4 mg l-1 of sodium selenate can be applied to improve the growth and nutritional condition of the peppermint.

High nitrate (NO3−) in vegetables, especially in leafy vegetables poses threaten to human health. Selenium (Se) is an important element for maintaining human health, and exogenous Se application during vegetable and crop production is an effective way to prevent Se deficiency in human bodies. Exogenous Se shows a positive function on plant growth and nutrition uptake under abiotic and biotic stresses. However, the influence of exogenous Se on NO3− accumulation in hydroponic leafy vegetables is still not clear.

The present study was conducted in a completely randomized design with four replications at Research Greenhouse of Lorestan University. In this study, hydroponic lettuce (Lactuca sativa L. var. Grin leek) and spinach (Spinacia oleracea L. var. Sirius) plants were subjected to six different concentrations (0, 0.1, 0.5, 5, 10 and 50 μmol L–1) of Se as Na2SeO3. Zero concentration was considered as control. The modified Hoagland nutrient solution were prepared and 8 liters was added to each pot. The nutrient solutions were replaced with fresh solution every five days throughout this experiment. After the emergence of new roots in the nutrient solution, treatment was applied and selenium was added to the pots at a specific concentration. After Se treatment for 40 days, three plants were randomly harvested from each treatment. The effects of Se on plant growth, NO3− content, activities of nitrogen metabolism enzymes, photosynthetic capacity and glutathione peroxidase enzyme activity of lettuce (Lactuca sativa L.) and spinach (Spinacia oleracea L.) were investigated. The second youngest, fully expanded leaf was used to monitor photosynthetic capacity using chlorophyll meter and portable photosynthetic apparatus, respectively. Nitrate concentration in dried samples was determined based on nitrate to nitrite reductions in the vicinity of zinc powder and hydrogen ion. Data preparation was done in the Excel program and data analysis was done using SPSS 16 software. The means comparison of the treatments was done by LSD test and finally, the figures were drawn using MS Excel.

The results showed that the lowest and highest biomass in both plants were observed in 50 and 5 μmol L–1 Se treatments, respectively. Different levels of selenium had no significant effect on root fresh weight in spinach. However, in the lettuce, at 50 μmol L–1, the root fresh weight significantly decreased compared to the 5 μmol L–1. Moreover, exogenous Se positively decreased NO3− content and this effect was concentration-dependent. The lowest NO3− content was obtained under 5 μmol L–1 Se treatment.NO3− content in lettuce was lower than that of spinach in all treatments. The application of Se enhanced photosynthetic capacity by increasing the stomatal conductance, photosynthesis rate and chlorophyll content of plants. No significant difference (p ≤0.05) was observed in spinach in chlorophyll, stomatal conductance and photosynthetic rate between 10 and 5 μmol L–1, however, in lettuce this difference was significant. Chlorophyll content in lettuce was higher than spinach in all treatments. The best concentration for photosynthetic capacity in both plants was five μmol L–1, which could explain similar changes in root and shoot dry weight in the different treatments. The results showed that low selenium concentrations (≤5 μmol L–1) stimulated NO3− assimilation by enhancing nitrate reductase (NR), nitrite reductase (NiR) and glutamine synthetase (GS) activities. The lowest nitrate reductase activity in lettuce and spinach was 50 μmol L–1 and control, respectively. In all treatments, nitrate reductase activity in lettuce was higher than in spinach. The reaction of nitrate reductase to selenium application was similar to nitrate reductase activity. Glutamine synthetase activity in both plants increased with increasing selenium concentration. However, as the concentration increased (≥ 5 μmol L–1), the activity of this enzyme began to decrease. In addition, the activity of this enzyme was higher than control in all treatments. Selenium also increased glutathione peroxidase concentration. A significant increase in glutathione peroxidase activity at five μmol L–1 was observed compared to the other treatments in lettuce. However, there was no significant difference in the activity of this enzyme in spinach at concentrations of 5 and 0.5 μmol L–1.

These results provided direct evidence that exogenous Se showed positive function on decreasing NO3− accumulation via enhancing activities of nitrogen metabolism enzyme in both plants. This study suggested that five μmol L–1 Se could be used to reduce NO3− content and increased hydroponic lettuce and spinach yield.

Selenium (Se) is an important microelement for plants and has been shown to improve growth under normal and stressed conditions. In this study, effect of Se and nano-selenium (N-Se) on hydroponically-grown tomato (Lycopersicum esculentum Mill. cv. ‘Halil’) on photosynthesis, antioxidant activity and total polyphenolic content was assessed. A factorial experiment with three temperature levels and Se and Nano Se level was designed. All plants were first exposed to Se or N-Se [Se at 0 µM (control), 2.5 µM (Se1), 5 µM (Se2) and 8 µM (Se3)], while N-Se was applied at four levels [1 µM (N-Se1), 4 µM (N-Se2), 8 µM (N-Se3) and 12 µM (N-Se4)]. Plants were exposed to three temperature levels [optimal temperature (25.17 ± 2 °C day/night = T1), high temperature (40 °C for 24 hr = T2) and low (chilling) temperature (10 °C for 24 hr = T3)]. They were then placed at normal temperature conditions for 7 days and photosynthetic and antioxidant factors were measured. Based on the results, both temperature-related stresses had negative effect on tomato growth. However, under high temperature stress, photosynthetic rate, mesophyll conductance and photosynthetic water use efficiency improved significantly. While, cold stress significantly enhanced transpiration. Most photosynthetic parameters could be improved in the presence of Se and N-Se. In Se1 treatment, under the temperature stress, the best photosynthetis rate, respiration and mesophyll conductance were obtained and plant resistance was enhanced. In N-Se treatments, N-Se1 had the best results of photosynthetis rate, antioxidant and phenol. However, in the absence of stress, the use of Se or N-Se, especially at higher concentrations (i.e., 5 and 8 µM), negatively impacted photosynthetic rate, internal CO2 of stomata, mesophyll conductance and photosynthetic water use efficiency. In general, under the low and high temperature stress, the physiological parameters of tomato were improved in N-Se1 treatment.

Selenium is a metalloid that it is antioxidant characteristics is proved for humans, animals and plants. However, some plants are known as hyper accumulators for selenium and sometimes seems to be useful for growth of some plants. In this paper, we have studied the effect of different selenium concentrations on growth and morpho-physiological characteristics of spinach. Seeds of spinach were germinated in germinator and seedlings were transferred to hydroponic cultures. The seedlings were grown in Hogland´s solution with different selenium concentrations (in form of sodium selenite) of 0,1,2,4,6, and 10 mgL-1 SeO3-2. The experiment was conducted based on a completely randomized design with four replications. Four weeks after treatments, morphophysiological characteristics including plant biomass, length of shoot and root, number of leaves, amount of chlorophyll a and b were measured. The results showed that application of different selenium concentrations had significant effect on morphological and physiological characteristics of root and shoot consisting wet and dry weight, root and shoot length and amount of chlorophyll. In this experiment, increasing selenium concentrations (except in 1 mgL-1 SeO3-2 concentration) decreased amounts of all mentioned characters in comparison with control. Morphological symptoms of selenium toxicity on spinach was chlorosis on young leaves and significant reduction in root and shoot growth.