Seed Priming with Alpha Tocopherol Improves Morpho-Physiological Attributes of Okra under Saline Conditions

The alpha-tocopherol (Vitamin E) is naturally occurring antioxidant in plants, which plays a significant role in environmental stress tolerance. A pot trial was conducted to assess the role of exogenously applied alpha-tocopherol as seed priming agent in improving the morpho-physiological attributes of okra [Abelmoschus esculentus (L.) Moench] under saline conditions. Seeds of two okra varieties (Sabzpari and Noori) were treated with four alpha-tocopherol levels [0 (distilled water), 100,200 and 300 mg L-1] before sowing for 16 h and two salinity levels (0 and 100 mM NaCl) were established after seed sowing. Salt stress caused significant decrease in shoot and root dry weight, shoot length, photosynthetic pigments, gas exchange characteristics and Ca(2+)and K(+)ion contents, while increased level of Na(+)ions in shoot, root and fruit tissues was observed in tested okra varieties. Seed priming with 200 mg L-1 alpha-tocopherol increased dry biomass of shoot and root, their lengths, photosynthetic pigments including chlorophyll a, b and carotenoids, water use efficiency (A/E), transpiration rate (E), net CO2 assimilation rate (A), stomatal conductance (g(s)) and sub-stomatal CO2 concentration (C-i). Moreover, seed priming with various alpha-tocopherol levels also increased Ca(2+)uptake, while; no remarkable change was observed in the concentrations of Na+ and K+ ions in shoot, root and fruit tissues of okra. The okra variety Noori performed better than Sabzpari in all parameters. Inclusively, 200 and 300 mg L-1 of alpha-tocopherol were more effective in improving growth by demising brutal effects of salt stress at morpho-physiological levels as seed priming agent. Therefore, use of 200 to 300 mg L-1 levels of alpha-tocopherol as seed priming agent are recommended for growing okra in marginally to moderately saline soils. (C) 2018 Friends Science Publishers