The Positive Effect of Selenium on Nitrate Accumulation in Spinach (Spinacia oleracea L.) and Lettuce (Lactuca sativa L.)

علوم باغبانی

Article 10, Volume 34, Issue 2 - Serial Number 46, September 2020, Pages 321-334   

Document Type: Research Article

DOI: 10.22067/jhorts4.v34i2.85540

Authors

Mahboobeh Jalali^* ; Negin Salehi Chegeni

Department of Soil Sciences, College of Agriculture and Natural Resources, Lorestan University, Khorramabad, Iran

Abstract

Introduction: 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.
Materials and Methods: 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.
Results and Discussion: 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.
Conclusion: 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.

Keywords

Nitrate; Nitrogen metabolism enzyme; Photosynthetic parameters; Selenium

References

1. Aslam M., Harbit K.B. and Huffaker R.C. 1990. Comparative effects of selenium and selenate on nitrate assimilation in barley seedlings. Plant, Cell and Environment, 13: 773–782.

2. Bian Z.H., Cheng R.F., Yang Q.C., Wang J. and Lu C.G. 2016. Continuous light from red, blue, and green light-emitting diodes reduces nitrate content and enhances phytochemical concentrations and antioxidant capacity in lettuce. Journal of American Society for Horticultural Science, 141: 186–195.

3. Bian Z.H., Lei B., Cheng R.F., Wang Yu., Li T. and Yang Q.C. 2020. Selenium distribution and nitrate metabolism in hydroponic lettuce (Lactuca sativa L.): Effects of selenium forms and light spectra. Journal of Integrative Agriculture, 19: 133–144.

4. Cartes P., Gianfreda L. and Mora M.L. 2005. Uptake of selenium and its antioxidant activity in ryegrass when applied as selenite and selenium forms. Plant and Soil, 276: 359–367.

5. Champigny M.L. 1995. Integration of photosynthetic carbon and nitrogen metabolism in higher plants. Photosynthesis Research, 46: 117–127.

6. Chen B.M., Wang Z.H., Li S.X., Wang G.X., Song H.X. and Wang X.N. 2004. Effects of nitrate supply on plant growth, nitrate accumulation, metabolic nitrate concentration and nitrate reductase activity in three leafy vegetables. Plant Science, 167: 635-643.

7. Chen T.F., Zheng W.J., Luo Y., Yang F., Bai Y. and Tu F. 2005. Effects of selenium stress on photosynthetic pigment contents and growth of Chlorella vulgaris. Journal of Plant Physiology and Molecular Biology, 31: 369-373.

8. Djanaguiraman M., Devi D.D., Shanker A.K., Sheeba A. and Bangarusamy U. 2005. Selenium an antioxidative protectant in soybean during senescence. Plant and Soil, 272: 77-86.

9. Dordas C.A. and Sioulas C. 2008. Safflower yield, chlorophyll content, photosynthesis, and water use efficiency response to nitrogen fertilization under rainfed conditions. Industrial Crops and Products, 27: 75-85.

10. Dziubinskaa H., Filekb M., Krol E. and Trebacz K. 2010. Cadmium and selenium modulate slow vacuolar channels in rape (Brassica napus) vacuoles. Journal of Plant Physiology, 167: 1566–1570.

11. Feng R., Wei C. and Tu S. 2013. The roles of selenium in protecting plants against abiotic stresses. Environmental and Experimental Botany, 87: 58–68.

12. Forde B.G. and Lea P.J. 2007. Glutamate in plants: Metabolism, regulation, and signaling. Journal of Experimental Botany, 58: 2339–2358.

13. Germ M., Stibilj V. and Kreft I. 2007. Metabolic importance of selenium for plants. The European Journal of Plant Science and Biotechnology, 1: 91-97.

14. Han-Wens S., Jing H., Shu-Xuan L. and Wei-Jun K. 2010. Protective role of selenium on garlic growth under cadmium stress. Communications in Soil Science and Plant Analysis, 41: 1195-1204.

15. Harris J., Schneberg K.A. and Pilon-Smits E.A. 2014. Sulfur-selenium-molybdenum interactions distinguish selenium hyperaccumulator Stanleya pinnata from non-hyperaccumulator Brassica juncea (Brassicaceae). Planta, 239: 479–491.

16. Hawrylak B., Matraszek R. and Szynanska M. 2007. Response of lettuce (Lactuca sativa L.) to selenium in nutrient solution contaminated with nickel. Vegetable Crops Research Bulletin, 67: 63-70.

17. Hawrylak-Nowak B. 2008. Changes in anthocyanin content as indicator of maize sensitivity to selenium. Journal of Plant Nutrition, 31: 1232–1242.

18. Jahid A.M., Kumar S., Thakur P., Sharma S., Kau Raman Preet N., Kaur D.P., Bhandhari K., Kaushal N., Singh K., Srivastav, A. and Nayyar H. 2010. Promotion of growth in mungbean (Phaseolus aureus Roxb.) by selenium is associated with stimulation of carbohydrate metabolism. Biological Trace Element Research, 143: 530-539.

19. Jozwiak W., Mleczek M. and Politycka B. 2016. The effect of exogenous selenium on the growth and photosynthetic pigments of cucumber seedlings. Fresenius Environmental Bulletion, 25: 142–152.

20. Kaiser J.J. and Lewis O.A.M. 1984. Nitrate reductase and glutamine synthetase activity in leaves and roots of nitrate-fed Helianthus annuus L. Plant and Soil, 70: 127–130.

21. Kieliszek M and Blazejak S. 2013. Selenium: Significance, and outlook for supplementation. Nutrition, 29: 713–718.

22. Lei B, Bian Z.H, Yang Q.C., Wang J., Cheng R.F, LI Kun1, Liu W., Zhang Y., Fang H. and Tong Y. 2018. The positive function of selenium supplementation on reducing nitrate accumulation in hydroponic lettuce (Lactuca sativa L.). Journal of Integrative Agriculture, 17: 837–846.

23. Liu D.D., Li H., Wang Y.Z., Ying Z.Z., Bian Z.W., Zhu W.L., Liu W., Yang L.F. and Jiang D.H. 2017. How exogenous selenium affects anthocyanin accumulation and biosynthesis-related gene expression in purple lettuce. Polish Journal of Environmental Studies, 26: 717–722.

24. Malorgio F., Diaz k., Ferrante A. 2009. Effects of selenium addition on minimally processed leafy vegetables grown in a floating system. Journal Science Food and Agriculture, 89: 2243–2251.

25. Nickel, R. S. and Cunningham, B. A. (1969) Improved peroxidase assay method using Ieuco 2,3,6-trichloroindophenol and application to comparative measurements of peroxidase catalysis. Annals of Biomedical Engineering, 27: 292-299.

26. Nowak J, Kaklewski K, Ligocki M. 2004. Influence of selenium on oxidoreductive enzymes activity in soil and in plants. Soil Biology and Biochemistry, 36, 1553–1558.

27. Padmaja K., Prasad D.D.K., and Prasad A.R.K. 1989. Effect of selenium on chlorophyll biosynthesis in mung bean seedlings. Phytochemistry, 28: 3321-3324.

28. Rani N, Dhillon K S, Dhillon S K. 2005. Critical levels of selenium in different crops grown in an alkaline silty loam soil treated with selenium-Se. Plant Soil, 277, 367–374.

29. Rios J J, Blasco B, Rosales M A, Sanchez-Rodriguez E, Leyva R, Cervilla L M, Romero L, Ruiz J M. 2010. Response of nitrogen metabolism in lettuce plants subjected to different doses and forms of selenium. Journal of American Society for Horticultural Science, 90, 1914–1919.

30. Ruiz J M, Rivero R M, Romero L. 2007. Comparative effect of Al, Se, and Mo toxicity on NO3 - assimilation in sunflower (Helianthus annuus L.) plants. Journal of Environmental Management, 83, 207–212.

31. Saffaryazdi, A., Lahouti, M., Ganjeali, A., and Bayat, H. 2012. Impact of selenium supplementation on growth and selenium accumulation on spinach (Spinacia oleracea L.) Plants. Natulae Scientia Biologicae. 4: 95-100.

32. Santamaria P. 2006. Nitrate in vegetables: Toxicity, content, intake and EC regulation. Journal of the Science of Food and Agriculture, 86, 10–17.

33. Seppanen, M., Turakainen, M. and Hartikainen, H. 2003. Selenium effects on oxidative stress in potato. Plant Science, 165: 311-319.

34. Schiavon, M., Acqua, S.D., Mietto, A., Pilon-Smits, E.A.H., Sambo, P., Masi, A. and Malagoli, M. 2013. Selenium fertilization alters the chemical composition and antioxidant constituents of tomato (Solanum lycopersicon L.). Journal of Agricultural and Food Chemistry. 61: 10542−10554.

35. Sharma, S., Bansal, A., Dhillon, S.K. and Dhillon, K.S. 2010. Comparative effects of selenate and selenite on growth and biochemical composition of rapeseed (Brassica napus L.). Plant Soil. 329: 339–348.

36. Shekari L, Kamelmanesh M M, Mozafariyan M, Hasanuzzaman M, Sadeghi F. 2017. Role of selenium in mitigation of cadmium toxicity in pepper grown in hydroponic condition. Journal of Plant Nutrition, 40, 761–772.

37. Schwarz K, Foltz C M. 1957. Selenium as an integral part of Factor 3 against dietary degeneration. Journal of the American Chemical Society, 79, 3292–3293.

38. Singh J. P., 1988. A rapid method for determination of nitrate in soil and plant extract. Plant and Soil 11: 137-139.

39. Smolen, S., and Sady, W. 2009. The effect of various nitrogen fertilization and foliar nutrition regimes on the concentrations of sugars, carotenoids and phenolic compounds in carrot (Daucus carota L.). Scientia Horticulturae. 120: 315–324.

40. Sun H Y, Wang X Y, Dai H X, Zhang G P, Wu F B. 2013. Effect of exogenous glutathione and selenium on cadmiuminduced changes in cadmium and mineral concentrations and antioxidative metabolism in maize seedlings. Asian Journal of Chemistry, 25, 2970–2975.

41. Stewart, G. R., Lee, J. A. and Orebamjo, T. O. (1972) Nitrogen metabolism of halophyte: Nitrate reductase activity and utilization. New Phytologist 72: 539-546.

42. Takeda T, Kondo K, Ueda K, Iida A. 2016. Antioxidant responses of selenium-enriched broccoli sprout (Brassica oleracea) to paraquat exposure. Biomedical Research on Trace Elements, 27, 8–14.

43. Turakainen M, Hartikainen H, Seppanen M M. 2004. Effects of selenium treatments on potato (Solanum tuberosum L.) growth and concentrations of soluble sugars and starch. Journal of Agricultural and Food Chemistry, 52: 5378–5382.

44. Wu L., and Huang Z.Z. 1991. Chloride and sulfate salinity effects on selenium accumulation by Tall Fescue. Crop Science Society of American, 31: 114-118.

45. Xue, T., Hartikainen, H. and Piironen, V. 2001. Antioxidative and growth promoting effect of selenium in senescing lettuce. Plant Soil, 237: 55-61.

46. Zhang M, Tang S, Huang X, Zhang F, Pang Y, Huang Q Y, Yi Q. 2014. Selenium uptake, 450 dynamic changes in selenium content and its influence on photosynthesis and chlorophyll fluorescence in rice (Oryza sativa L.). Environmental and Experimental Botany, 107: 39–45.