Selenium (Se) is an essential micronutrient with a range of physiological and antioxidative properties. Reports regarding effect of Se application on plants growth and development are not consistent. The identification of effective Se dose and application method is crucial for better understanding of Se translocation within crop plants under drought stress. The present study aimed at investigating the role of Se supplementation in improving the drought tolerance potential of wheat at early growth stages. Two wheat genotypes (Kohistan-97 and Pasban-90) were grown in plastic pots (8 × 12？cm) in green/wire-house experiments. Results demonstrated that the growth and biomass of seedlings increased at high Se foliar concentrations and decreased at low and high Se fertigation levels. The seedlings exhibited the highest values for plant height stress tolerance index (PHSI), root length stress tolerance index (RLSI), dry matter stress tolerance index (DMSI), and fresh matter stress tolerance indices (FMSI) at Se fertigation level of 7.35？μM, whereas Se foliar treatment of 7.06？μM resulted in maximum values for these indices. The seedlings foliarly sprayed with Se maintained higher DMSI and FMSI than those fertigated with Se which suggests that Se foliar spray is more effective than Se fertigation for improving drought tolerance. 1. Introduction Drought stress has emerged as the single most critical threat to world food security. It seriously limits agricultural productivity, especially in areas where rainfall is limiting or unreliable, so improving yield under limited water conditions has become a crucial target for arid and semiarid regions of the world [1–3]. Exposure to drought stress poses serious challenges for the survival of plants, because it results in impaired germination and seedling growth [4] and affects many growth variables of the plant ？[5, 6], thus reducing fitness and harvestable yield of plants [3]. The physiological and antioxidant properties of selenium (Se) have increased the curiosity of many biologists in recent past. Although it does not take part in various vital metabolic processes in plants, it may help to reduce the damage under physiological stresses [7, 8]. Recently, Se has been reported to counteract the detrimental effects of various environmental stresses such as heavy metals [9], UV-B [10, 11], excess water [12], salt [13], cold [14], high temperature [15], senescence [16], and desiccation [17]. However, reports on the role of Se in plants under water stress conditions are scanty. It may regulate water status [18] and increase
References
[1]
M. M. Chaves and M. M. Oliveira, “Mechanisms underlying plant resilience to water deficits: prospects for water-saving agriculture,” Journal of Experimental Botany, vol. 55, no. 407, pp. 2365–2384, 2004.
[2]
J. J. Zhang, G. P. Hao, Z. Y. Wu et al., “Nucleotide variation in ATHK1 region of Arabidopsis thaliana and its association study with drought tolerance,” African Journal of Biotechnology, vol. 7, no. 3, pp. 224–233, 2008.
[3]
F. Nawaz, R. Ahmad, E. A. Waraich, M. S. Naeem, and R. N. Shabbir, “Nutrient uptake, physiological responses, and yield attributes of wheat (Triticum aestivum l.) exposed to early and late drought stress,” Journal of Plant Nutrition, vol. 35, no. 6, pp. 961–974, 2012.
[4]
C. M. Ashraf and S. Abu-Shakra, “Wheat seed germination under low temperature and moisture stress,” Agron Journal, vol. 70, pp. 135–139, 1978.
[5]
X. Tian and Y. Lei, “Nitric oxide treatment alleviates drought stress in wheat seedlings,” Biologia Plantarum, vol. 50, no. 4, pp. 775–778, 2006.
[6]
F. Zhao, F. J. Lopez-Bellido, C. W. Gray, W. R. Whalley, L. J. Clark, and S. P. McGrath, “Effects of soil compaction and irrigation on the concentrations of selenium and arsenic in wheat grains,” Science of the Total Environment, vol. 372, no. 2-3, pp. 433–439, 2007.
[7]
B. Hanson, G. F. Garifullina, S. D. Lindblom et al., “Selenium accumulation protects Brassica juncea from invertebrate herbivory and fungal infection,” New Phytologist, vol. 159, no. 2, pp. 461–469, 2003.
[8]
M. Sepp？nen, M. Turakainen, and H. Hartikainen, “Selenium effects on oxidative stress in potato,” Plant Science, vol. 165, no. 2, pp. 311–319, 2003.
[9]
M. Kumar, A. J. Bijo, R. S. Baghel, C. R. K. Reddy, and B. Jha, “Selenium and spermine alleviate cadmium induced toxicity in the red seaweed Gracilaria dura by regulating antioxidants and DNA methylation,” Plant Physiology and Biochemistry, vol. 51, pp. 129–138, 2012.
[10]
X. Yao, J. Chu, and C. Ba, “Antioxidant responses of wheat seedlings to exogenous selenium supply under enhanced ultraviolet-B,” Biological Trace Element Research, vol. 136, no. 1, pp. 96–105, 2010.
[11]
X. Q. Yao, J. Z. Chu, and C. J. Ba, “Responses of wheat roots to exogenous selenium supply under enhanced ultraviolet-B,” Biological Trace Element Research, vol. 137, no. 2, pp. 244–252, 2010.
[12]
C. Wang, “Water-stress mitigation by selenium in Trifolium repens L.,” Journal of Plant Nutrition and Soil Science, vol. 174, no. 2, pp. 276–282, 2011.
[13]
M. Hasanuzzaman, M. A. Hossain, and M. Fujita, “Selenium-induced up-regulation of the antioxidant defense and methylglyoxal detoxification system reduces salinity-induced damage in rapeseed seedlings,” Biological Trace Element Research, vol. 143, no. 3, pp. 1704–1721, 2011.
[14]
J. Chu, X. Yao, and Z. Zhang, “Responses of wheat seedlings to exogenous selenium supply under cold stress,” Biological Trace Element Research, vol. 136, no. 3, pp. 355–363, 2010.
[15]
M. Djanaguiraman, P. V. V. Prasad, and M. Seppanen, “Selenium protects sorghum leaves from oxidative damage under high temperature stress by enhancing antioxidant defense system,” Plant Physiology and Biochemistry, vol. 48, no. 12, pp. 999–1007, 2010.
[16]
H. Hartikainen, T. Xue, and V. Piironen, “Selenium as an anti-oxidant and pro-oxidant in ryegrass,” Plant and Soil, vol. 225, no. 1-2, pp. 193–200, 2000.
[17]
S. Pukacka, E. Ratajczak, and E. Kalemba, “The protective role of selenium in recalcitrant Acer saccharium L. seeds subjected to desiccation,” Journal of Plant Physiology, vol. 168, no. 3, pp. 220–225, 2011.
[18]
V. V. Kuznetsov, V. P. Kholodova, V. I. V. Kuznetsov, and B. A. Yagodin, “Selenium regulates the water status of plants exposed to drought,” Doklady Biological Sciences, vol. 390, pp. 266–268, 2003.
[19]
F. Nawaz, M. Y. Ashraf, R. Ahmad, and E. A. Waraich, “Selenium (Se) seed priming induced growth and biochemical changes in wheat under water deficit conditions,” Biological Trace Element Research, vol. 151, no. 2, pp. 284–293, 2013.
[20]
X. Yao, J. Chu, and G. Wang, “Effects of selenium on wheat seedlings under drought stress,” Biological Trace Element Research, vol. 130, no. 3, pp. 283–290, 2009.
[21]
M. Hasanuzzaman and M. Fujita, “Selenium pretreatment upregulates the antioxidant defense and methylglyoxal detoxification system and confers enhanced tolerance to drought stress in rapeseed seedlings,” Biological Trace Element Research, vol. 143, no. 3, pp. 1758–1776, 2011.
[22]
S. Bittman, W. T. Buckley, K. Zaychuk, and E. A. P. Brown, “Seed coating for enhancing the level of selenium in crops,” USA Patent No. 6,058, 649, 2000.
[23]
L. D. Temmerman, N. Waegeneers, C. Thiry, G. D. Laing, F. Tack, and A. Ruttens, “Selenium content of Belgian cultivated soils and its uptake by field crops and vegetables,” Science of the Total Environment, vol. 468–469, pp. 77–82, 2013.
[24]
P. F. Boldrin, V. Faquin, S. J. Ramos, K. V. F. Boldrin, F. W. ávila, and L. R. G. Guilherme, “Soil and foliar application of selenium in rice biofortification,” Journal of Food Composition and Analysis, vol. 31, pp. 238–244, 2013.
[25]
Y. Wang, X. Wang, and Y. Wong, “Generation of selenium-enriched rice with enhanced grain yield, selenium content and bioavailability through fertilisation with selenite,” Food Chemistry, vol. 141, no. 3, pp. 2385–2393, 2013.
[26]
A. D. C. Chilimba, S. D. Young, C. R. Black, M. C. Meacham, J. Lammel, and M. R. Broadley, “Agronomic biofortification of maize with selenium (Se) in Malawi,” Field Crops Research, vol. 125, pp. 118–128, 2012.
[27]
J. Yan, F. Wang, H. Qin et al., “Natural Variation in Grain Selenium Concentration of Wild Barley, Hordeum spontaneum, Populations from Israel,” Biological Trace Element Research, vol. 142, no. 3, pp. 773–786, 2011.
[28]
F. Yang, L. Chen, Q. Hu, and G. Pan, “Effect of the application of selenium on selenium content of soybean and its products,” Biological Trace Element Research, vol. 93, no. 1–3, pp. 249–256, 2003.
[29]
E. Kápolna, K. H. Laursen, S. Husted, and E. H. Larsen, “Bio-fortification and isotopic labelling of Se metabolites in onions and carrots following foliar application of Se and 77Se,” Food Chemistry, vol. 133, no. 3, pp. 650–657, 2012.
[30]
E. Kápolna, P. R. Hillestr？m, K. H. Laursen, S. Husted, and E. H. Larsen, “Effect of foliar application of selenium on its uptake and speciation in carrot,” Food Chemistry, vol. 115, no. 4, pp. 1357–1363, 2009.
[31]
K. R. Hladun, D. R. Parker, K. D. Tran, and J. T. Trumble, “Effects of selenium accumulation on phytotoxicity, herbivory, and pollination ecology in radish (Raphanus sativus L.),” Environmental Pollution, vol. 172, pp. 70–75, 2013.
[32]
P. P？ldma, T. T？nutare, A. Viitak, A. Luik, and U. Moor, “Effect of selenium treatment on mineral nutrition, bulb size, and antioxidant properties of garlic (Allium sativum L.),” Journal of Agricultural and Food Chemistry, vol. 59, no. 10, pp. 5498–5503, 2011.
[33]
D. Curtin, R. Hanson, T. N. Lindley, and R. C. Butler, “Selenium concentration in wheat (Triticum aestivum) grain as influenced by method, rate, and timing of sodium selenate application,” New Zealand Journal of Crop and Horticultural Science, vol. 34, no. 4, pp. 329–339, 2006.
[34]
N. Terry, A. M. Zayed, M. P. de Souza, and A. S. Tarun, “Selenium in higher plants,” Annual Review of Plant Physiology and Plant Molecular Biology, vol. 51, pp. 401–432, 2000.
[35]
R. L. Mikkelsen, A. L. Page, and F.T. Bingham, “Factors affecting selenium accumulation by agricultural crops,” in Selenium in Agriculture and the Environment, L. W. Jacobs, Ed., SSSA Special Publication Number 23, pp. 65–94, Soil Science Society of America, Madison, Wis, USA, 1989.
[36]
A. Kabata-Pendias and H. Pendias, Trace Elements in Soils and Plants, CRC Press, Boca Raton, Fla, USA, 2nd edition, 1992.
[37]
C. Kahakachchi, H. T. Boakye, P. C. Uden, and J. F. Tyson, “Chromatographic speciation of anionic and neutral selenium compounds in Se-accumulating Brassica juncea (Indian mustard) and in selenized yeast,” Journal of Chromatography A, vol. 1054, no. 1-2, pp. 303–312, 2004.
[38]
A. Zayed, C. M. Lytle, and N. Terry, “Accumulation and volatilization of different chemical species of selenium by plants,” Planta, vol. 206, no. 2, pp. 284–292, 1998.
[39]
M. Y. Ashraf, F. Hussain, J. Akhter, A. Gul, M. Ross, and G. Ebert, “Effect of different sources and rates of nitrogen and supra optimal level of potassium fertilization on growth, yield and nutrient uptake by sugarcane grown under saline conditions,” Pakistan Journal of Botany, vol. 40, no. 4, pp. 1521–1531, 2008.
[40]
F. Nawaz, Wheat response to exogenous selenium supply under drought stress [Ph.D. dissertation], University of Agriculture, Faisalabad, Pakistan, 2014.
[41]
A. Latif and M. M. Iqbal, “Fertigation techniques,” in Proceedings of the Workshop on Technologies for Sustainable Agriculture (NIAB '01), pp. 155–159, Faisalabad, Pakistan, 2001.
[42]
M. Djanaguiraman, D. D. Devi, A. K. Shanker, J. A. Sheeba, and U. Bangarusamy, “Selenium—an antioxidative protectant in soybean during senescence,” Plant and Soil, vol. 272, no. 1-2, pp. 77–86, 2005.
[43]
K. L. Larson, “Drought injury and resistance of crop plants,” in Physiological Aspects of Dry Land Farming, S. U. Gupta, Ed., pp. 147–162, Oxford & IBH Publishing, New Delhi, India, 1992.
[44]
H. Hartikainen, “Biogeochemistry of selenium and its impact on food chain quality and human health,” Journal of Trace Elements in Medicine and Biology, vol. 18, no. 4, pp. 309–318, 2005.
[45]
P. Smrkolj, M. Osvald, J. Osvald, and V. Stibilj, “Selenium uptake and species distribution in selenium-enriched bean (Phaseolus vulgaris L.) seeds obtained by two different cultivations,” European Food Research and Technology, vol. 225, no. 2, pp. 233–237, 2007.
[46]
B. Z. Bai, J. Z. Jin, S. Bai, and L. P. Huang, “Improvement of TTC method determining root activity in corn,” Maize Science, vol. 2, pp. 44–47, 1994 (Chinese).
[47]
C. L. Carlson, D. I. Kaplan, and D. C. Adriano, “Effects of selenium on germination and radicle elongation of selected agronomic species,” Environmental and Experimental Botany, vol. 29, no. 4, pp. 493–498, 1989.
[48]
S. A. Valadabadi, A. H. Shiranirad, and H. A. Farahani, “Ecophysiological influences of zeolite and selenium on water deficit stress tolerance in different rapeseed cultivars,” Journal of Ecology and the Natural Environment, vol. 2, pp. 154–159, 2010.
[49]
G. Ok？u, M. D. Kaya, and M. Atak, “Effects of salt and drought stresses on germination and seedling growth of pea (Pisum sativum L.),” Turkish Journal of Agriculture and Forestry, vol. 29, no. 4, pp. 237–242, 2005.
[50]
M. Ya？mur and D. Kaydan, “Alleviation of osmotic stress of water and salt in germination and seedling growth of triticale with seed priming treatments,” African Journal of Biotechnology, vol. 7, no. 13, pp. 2156–2162, 2008.
[51]
J. L. Hopper and D. R. Parker, “Plant availability of selenite and selenate as influenced by the competing ions phosphate and sulfate,” Plant and Soil, vol. 210, no. 2, pp. 199–207, 1999.
[52]
P. Ximénez-Embún, I. Alonso, Y. Madrid-Albarran, and C. Camara, “Establishment of selenium uptake and species distribution in lupine, Indian mustard, and sunflower plants,” Journal of Agricultural and Food Chemistry, vol. 52, pp. 832–838, 2004.
[53]
M. ？abanowska, M. Filek, J. Ko？cielniak, M. Kurdziel, E. Kuli？, and H. Hartikainen, “The effects of short-term selenium stress on Polish and Finnish wheat seedlings-EPR, enzymatic and fluorescence studies,” Journal of Plant Physiology, vol. 169, no. 3, pp. 275–284, 2012.
[54]
M. Vítová, K. Bi？ová, M. Hlavová, V. Zachleder, M. Rucki, and M. Cí？ková, “Glutathione peroxidase activity in the selenium-treated alga Scenedesmus quadricauda,” Aquatic Toxicology, vol. 102, no. 1-2, pp. 87–94, 2011.
[55]
Y. Wang, X. Wang, and Y. Wong, “Proteomics analysis reveals multiple regulatory mechanisms in response to selenium in rice,” Journal of Proteomics, vol. 75, no. 6, pp. 1849–1866, 2012.
[56]
T. Xue, H. Hartikainen, and V. Piironen, “Antioxidative and growth-promoting effect of selenium on senescing lettuce,” Plant and Soil, vol. 237, no. 1, pp. 55–61, 2001.
[57]
Q. Hu, G. Pan, and J. Zhu, “Effect of selenium on green tea preservation quality and amino acid composition of tea protein,” Journal of Horticultural Science and Biotechnology, vol. 76, no. 3, pp. 344–346, 2001.
[58]
M. Turakainen, H. Hartikainen, and M. M. Sepp？nen, “Effects of selenium treatments on potato (Solanum tuberosum L.) growth and concentrations of soluble sugars and starch,” Journal of Agricultural and Food Chemistry, vol. 52, no. 17, pp. 5378–5382, 2004.
[59]
M. Germ, “The response of two potato cultivars on combined effects of selenium and drought,” Acta Agriculturae Slovenica, vol. 91, no. 1, pp. 121–137, 2008.
[60]
G. Habibi, “Effect of drought stress and selenium spraying on photosynthesis and antioxidant activity of spring barley,” Acta Agriculturae Slovenica, vol. 101, no. 1, pp. 31–39, 2013.
[61]
P. Wójcik, “Uptake of mineral nutrients from foliar fertilization,” Journal of Fruit and Ornamental Plant Research, vol. 12, pp. 201–218, 2004.
[62]
H. Marschner, Mineral Nutrition of Higher Plants, Academic Press, London, UK, 1995.
