INTERNATIONAL JOURNAL OF AGRICULTURE & BIOLOGY ISSN Print: 1560–8530; ISSN Online: 1814–9596 17–0084/2017/19–4–771–778 DOI: 10.17957/IJAB/15.0356 http://www.fspublishers.org Full Length Article To cite this paper: Sarwar, M., M. Amjad and C.M. Ayyub, 2017. Alleviation of salt stress in cucumber (Cucumis sativus) through seed priming with triacontanol. Int. J. Agric. Biol., 19: 771‒778 Alleviation of Salt Stress in Cucumber (Cucumis sativus) through Seed Priming with Triacontanol Mubeen Sarwar * , Muhammad Amjad and C.M. Ayyub Institute of Horticultural Sciences, University of Agriculture, Faisalabad, Pakistan, 38000 * For correspondence: mubeensarwar4@yahoo.com Abstract The present study elucidated the role of triacontanol in regulating seed germination and seedling vigour of four cucumber cultivars under salt stress (50 mM NaCl). Seeds were soaked in aerated solution of triacontanol @ 25 μM, 50 μM for 12 h prior to sowing and untreated seeds were used as control. Priming enhanced the emergence rate, uniformity and early growth of cucumber seedlings under normal and saline conditions. Though, plants exposed to salt stress and seeds not treated with triacontanol showed poor performance in growth, physiology and biochemical attributes. However, priming with 25 and 50 μM triacontanol was very effective in decreasing time to start emergence, improved final emergence, shoot/root lengths, seedling dry weight, gas exchange attributes, chlorophyll and proline contents under saline conditions. Nonetheless, maximum relief from salt stress in all attributes was observed at 50 μM triacontanol. In conclusion, triacontanol can be successfully employed to improve the germination capacity and stand establishment of cucumber under saline conditions by reducing the deleterious effects of salinity. © 2017 Friends Science Publishers Keywords: Priming; Germination; Salt stress; Cucumber; Gas exchange attributes Abbreviations: Triacontanol = Tria, Photosynthesis rate = pn, Stomatal conductance = gs, Transpiration = E, Water use Efficiency = WUE, Mean emergence time = MET, Final emergence percentage = FEP, Emergence index = EI Introduction Plants reveal many adaptive strategies against abiotic stresses which finally mislead the plant growth (McCue and Hanson, 1990). It is recognized that beside other stresses, salt stress drastically restricts the plant growth and production (Abbas et al., 2010). In order to manage these stresses, plants adapt many variations in their physiology (Vinocur and Altman, 2005). It is reported that world 900 million hectare areas are affected by saline stress (Munns and Tester, 2008). Salinization disrupts the plant life cycle because of osmotic disturbance and specific ions toxicity (Vinocur and Altman, 2005) and osmotic stress produced water deficient environment that lead to physiological drought (Munns, 2005). Such hyper-osmotic disturbance and hyper ionic toxic lead to hang-up seed germination and growth of seedlings (Hasegawa et al., 2000). Salt stress causes cell dehydration due to accumulation of Na + and Cl - ions in soil (Gupta et al., 1993) which decreases the availability of K + ions, such conditions restricted the seeds to absorb water for embryo expansion; consequently inactivation of enzymes, nutrient starvation, ionic toxicity and oxidative stress in tissues (Gao et al., 2014). Moreover, excessive salt ions disintegrate radicle and plumule tissues and inhibited radicle growth, which delayed emergence of seedlings (Shahid et al., 2011; El Harfi et al., 2016). Seed germination significantly contributes to the establishment of vigorous crop stand (Ashraf et al., 2007). Seed priming is very effective strategy to improve seed germination and seedling establishment in several horticultural and agronomic crops under saline and non- saline environments (Ashraf and Foolad, 2005; Afzal et al., 2015). Seed priming in aerated solutions trigger metabolic activities which are essential for germination and improves uniformity, germination rate, final germination and stand establishment (Bradford, 1976; Afzal et al., 2016). Usually seed treatment is conducted in low water potential solution and incorporation of plant growth hormones for priming significantly improved the seed performance of several crops (Afzal et al., 2011) rice (Basra et al., 2006) and rice (Farooq et al., 2007). Triacontanol is a plant hormone (Singh et al., 2012) that stimulates plant growth at very low concentration when exogenously applied to various plant species like groundnut (Verma et al., 2011), pigeonpea (Pujari et al., 1998), maize, rice and wheat (Perveen et al., 2011; 2012 2013). It has described that triacontanol enhanced the photosynthetic activity (Eriksen et al., 1981) mineral nutrients and water uptake (Ivanov and Angelov, 1997; Chen et al., 2003) and improved the quantity of many organic solutes in leaf