Evaluation of Effect of Silicon on NaCl Tolerance in Annual Medicago scutellata L.

پژوهشهای زراعی ایران

Article 7, Volume 14, Issue 1 - Serial Number 41, April 2016, Pages 133-143   

Document Type: Research Article

DOI: 10.22067/gsc.v14i1.35409

Authors

M Azizi¹; A Abdolzadeh^{* 1}; P Mehrabanjoubani²; H. R Sadeghipour¹

¹Golestan University

²Sari Agricultural Sciences and Natural Resources University

Abstract

Introduction
Salinity is one of the most important stress resulting depletion of vegetation in large areas of the world including some regions of Iran. Reduction of plant growth due to salinity occurs with a range of mechanisms, including low external water potential, ion toxicity and interfere with the uptake. Silicon (Si) is the second most abundant element in soil and could efficiently mitigate the effects of various biotic and abiotic stresses, such as drought, heavy metal toxicity and salinity on plants. Medicago scutellata is an important leguminous forage crop throughout the world that could increase soil nitrogen content via reduction of atmospheric nitrogen. To our knowledge, no study have examined the interaction of salinity and Si nutrition in Medicago scutellata or how the beneficial effects of Si in salt-stressed M. scutellata plants (if any) are exerted. Accordingly, the aim of the present study was to evaluate the effect of silicon nutrition on salt tolerance of Medicago scutellata.
Materials and Methods
Seeds of alfalfa (Medicago scutellata L.) were sterilized with a 2.5% sodium hypochlorite solution and were incubated in a moistened paper towel. Then, they germinated in the dark at 255  C for 48 h. Healthy seedlings of uniform sizes were selected for hydroponic culture (Hoagland solution) in a 10×15×15 cm plastic pots. A factorial experiment carried out based on a completely randomized design with two factors. The first factor was salinity, including 0 and 100 mM NaCl and the second was silicon nutrition, including 0, 0.75 and 1.5 m.M sodium silicate. The pH of the nutrient solution was adjusted daily at 6.4  0.2 and nutrient solution was refreshed weekly. During the experiment, maximum and minimum air temperatures were 30ºC and 21ºC respectively, and the mean relative humidity was 67%. Four weeks after exerting the treatments, plants were harvested and used for the assessment of growth parameters and chemical analyses.
Results and Discussion
Salinity led to a significant reduction in both the fresh and dry weights of the plants. On the contrary, the dry weight of the plants improved significantly under saline conditions when Si was added to the medium, especially 1.5 mM Si. Salt treatment increased the concentration Na+ and decreased the concentration K+ significantly in both shoots and roots; however, Na+ concentration, reduced and K+ concentration increased due to Si application in salt treated plants. Similarly, Fe content decreased in shoot of plants due to salinity, whereas Si nutrition increased Fe content in plants suffered from salinity. The activity of catalase declined and the amount of hydrogen peroxide increased in plants under salinity. Conversely, Si treatments, especially, at 1.5 mM could recover the activity of this enzyme and reduced hydrogen peroxide content. Salinity imposed significant reduction in the contents of chlorophylls, total carotenoids and xanthophylls and soluble proteins. The amount of hydrogen peroxide, lipid peroxidation as well as electrolyte leakage via plant leaves increased due to salt stress. In contrast, the contents of chlorophylls, carotenoids and xanthophylls, soluble proteins increased following Si application. Also, the amount of hydrogen peroxide and rate of lipid peroxidation and electrolyte leakage decreased in salt-treated plants by Si application. Silicon nutrition can recover the chlorophyll content and the amount of soluble proteins on Medicago scutellata plants under salinity, which suggests that it plays a role in the suppression of oxidative stress. Si application also improved the chlorophyll content of tomato and barley under salt stress (Al-aghabary et al., 2004). The data reported in the present study show new aspect of the beneficial effect of Si on plants grown under saline condition. The application of Si prevented Na+ accumulation and enhanced K+ content in Medicago scutellata plants. Reduced Na+ accumulation improves the plant ROS scavenging capacity through increased antioxidant enzyme activity (Al-aghabary et al., 2004 Hashemi et al., 2010), accompanied by reducing lipid peroxidation. Consequently, photosynthetic pigments increased and membranes functionality improved by Si in plants under salinity (Liang et al., 2005).
Conclusions
The results indicated that 1.5 mM silicon application alleviated harmful effects salinity, probably through declined Na+ enhanced K+ content that increased antioxidant enzyme activity and reduced reducing oxidative stress. Consequently, photosynthetic pigments increased and membranes functionality improved with plants under salinity. In this regards, Si application led to an increased salt tolerance of Medicago scutellata. Further, field experiments are necessary for confirmation of the results and expedience of economic cost.

Keywords

Annual medicine plants; Silicon nutrition; Salinity alleviation

References

1. Jafari, M. 1995. Salinity and halophytes. Research Institute of Forests and Ranglands. N. 90. (in Persian).

2. Hoseini, A., 1995. Autecoloogical evaluation of Puccinellia distans in saline and sodic soils of north Gorgan region. Master's theses. Gorgan University of Agriculture and Natural Resource. (in Persian).

3. Sofi, S., and Janmohammadi, H. 2001. Animal Nutrition. Amiedi Publishing Center. Translated. Tabriz. (in Persian).

4. Dianatnejad, H., and Behfar, A. A. 1988. Deserts, Ecological researches, Plants in saline environments. translated International desert research center. (in Persian).

5. Ahmad R., Syed, H. Z., and Shoaib I. 1992. Role of silicon in salt tolerance of wheat (Triticom aestivum L.). Plant Science 85: 43-50.

6. Al-aghabary, K., Zhu, Z., and Shi, Q. 2004. Influence of silicon supply on chlorophyll content, chlorophyll fluorescence, and antioxidative enzyme activities in tomato plants under salt stress. Plant Nutrition 27: 2101-2115.

7. Arnon, D. I. 1949. Copper enzymes in isolated chloroplasts. ‎polyphenoloxidase in Beta Vulgaris. Plant Physiology 24: 1-15.

8. Ashraf, M. 1994. Breeding for salinity tolerance in plants. Critical Reviews in Plant Sciences 13: 17-42.

9. Blokhina, O., Virolainen, E., and Fagerstedt, K. 2003. Antioxidant, Oxidative damage and Oxygen deprivation salt-sensitive maize: a Review. Annals of Botany 91: 179-194.

10. Blum, A., and Ebercon, A. 1981. Cell Membrane Stability as a Measure of Drought and Heat Tolerance in Wheat. Crop Science 21: 43-47.

11. Bradford, M. 1976. A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. Analytical Biochemistry 72: 248-254.

12. Chance, B., and Maehly, C. 1955. Assay of catalase and peroxidases. Methods in Enzymology 2: 764-775.

13. Elliot, C. L., and Synder, G. H. 1991. Autoclave-Indused digestion for the colorimetric determination of silicon in Rice Straw. Journal of Agriculture Food Chemistry 39: 1118-1119.

14. Epstein, E. 1999. Silicon Annual review of Plant Physiology. Plant Molecular Biology 50: 641-664.

15. Farshidi, M., Abdolzadeh, A., and Sadeghipour, H. R. 2012. Silicon nutrition alleviates physiological disorders imposed by salinity in hydroponically grown canola (Brassica napus L.) plants. Acta physiologiae plantarum 56: 244-253.

16. Hashemi, A., Abdolzadeh, A., and Sadeghipour, H. R. 2010. Beneficial effects of silicon nutrition in alleviation salinity stress in hydroponically grown canola, Brassica napus L., plants. Soil Science and Plant Nutrition 56: 244-253.

17. Li, Q., Ma, C., and Shang, Q. 2007. Effects of silicon on photosynthesis and antioxidant enzymes of maize under drought stress. The journal of applied ecology 18: 531-536.

18. Liang, Y. C., Shen, Q. R., Shen, Z. G., and Ma, T. S. 1996. Effects of silicon on salinity tolerance of two barley cultivars. Journal of Plant Nutrition 19: 173-183.

19. Liang, Y. C., Zhang, W. H., Chen, Q., and Ding, R. X. 2005. Effects of silicon on tonoplast H+-ATPase and H+-PPase activity, fatty acid composition and fluidity in roots of salt-stressed barley (Hordeum vulgare L.). Environmental and Experimental Botany 53: 29-37.

20. Ma, J. F., and Takahashi, E. 2002. Soil, fertilizer, and plant silicon research in Japan, 1st ed. Elsevier, Amsterdam.

21. Mali, M., and Aery, N. C. 2008. Influence of silicon on growth, relative water contents and uptake of silicon, calcium and potassium in wheat grown in nutrient solution. Journal of Plant Nutrition 31: 1867-1876.

22. Marchner, H. 1995. Mineral nutrition of higher plants. Second Edition Academic Press. 890p. New York. Pp: 313-323.

23. Munns R. 2006. Physiological processes limiting plant growth in saline soil: some dogmas and hypotheses. Plant Cell and Environment 16: 15-24.

24. Sego, R. D. 1982. Chemical and microbiological properties. p. 105–111. In A.L. Page et al. (ed.) Methods of Soil Analysis. Part 2. 2nd ed. American Society of Agronomy, Soil Science.

25. Sergive, I., Alexieva, V., and Karanov, E. 1997. Effect of spermine, atrazine and combination between them on some endogeneus protective systems and stress markers in plants. Comptes rendus de l'Academie bulgare des Sciences 51: 121-124.

26. Shi, G., Cai, Q., Liu, C., and Wu, L. 2010. Silicon alleviates cadmium toxicity in peanut plants in relation to cadmium distribution and stimulation of antioxidative enzymes. Plant hormones and growth regulators 61: 45-52.

27. Szabolics, I. 1992. Salinization of soil and water its relation to desertification. Desertification Control bulletin 21: 32-37.

28. Tester, M., and Devenport, R. 2003. Na+ tolerance and Na+ transport in higher plants. Annals of Botany 91: 1-25.

29. Yeo, A. R., Flowers, S. A., Rao, G., Welfare, K., Senanayake, N., and Flowers, T. J. 1999. Silicon reduces sodium uptake in rice (Oryza sativa L.) in saline conditions and this is accounted for by a reduction in the transpirational bypass flow. Plant, Cell and Environment 22: 559-565.