Impact of Alpha-Tocopherol Seed Priming on Accumulation of Osmolytes and Ion Homeostasis in Sunflower (Helianthus annuus) under Salt Stress

Salt stress induces ion toxicity and nutritional disparity drastically affecting physiological functions in glycophytes. Previous studies reported that salt tolerant plant species maintain turgor by accumulating organic osmolytes and inorganic ions especially K +/-. This study was conducted to evaluate the role of alpha-tocopherol (alpha-toc) in accumulation of osmolytes and ion homeostasis in sunflower under salt stress. Seeds of sunflower cultivars FH-572 and FH-621 were immersed for 16 h in four levels [0 (dist. H2O), 100, 200 and 300 mg L-1] of alpha-toc before sowing in sand. Salt stress (120 mM NaCl) was applied with full strength Hoagland's nutrient solution, 35 days after seed sowing till maturity. Sunflower leaves were sampled 61 days after sowing seeds for analyses. Seed priming with alpha-toc boosted accumulation of glycine betaine, free amino acids and total soluble sugars to 53.25, 75 and 30% in FH-572 and 75, 31.25 and 25% in FH-621 respectively, under salt stress. Seed priming with alpha-toc caused significant reduction in Na conc., 5.71 and 25.15% in shoots of the FH-572 and FH-621 respectively in salt stress. Plants raised from alpha-toc primed seed showed increase in K+/Na+ ratio (4.76%) and Ca2+ conc. (6.5%) and decrease in Na+ conc. (8%) in roots of cv. FH-621 in salt stress but these modulations were non-significant. In conclusion, seed priming with 200 mg L-1 alpha-toc was effective in improving salinity tolerance in sunflower at early growth stages. (C) 2020 Friends Science Publishers