Foliar Spray of Alpha-Tocopherol Modulates Antioxidant Potential of Okra Fruit under Salt Stress

Abstract

As an antioxidant, alpha-tocopherol (α-Toc) protects plants from salinity-induced oxidative bursts. This study was conducted twice to determine the effect of α-Toc as a foliar spray (at 0 (no spray), 100, 200, and 300 mg L−1) to improve the yield and biochemical constituents of fresh green capsules of okra (Abelmoschus esculentus L. Moench) under salt stress (0 and 100 mM). Salt stress significantly reduced K+ and Ca2+ ion concentration and yield, whereas it increased H2O2, malondialdehyde (MDA), Na+, glycine betaine (GB), total free proline, total phenolics, and the activities of catalase (CAT), guaiacol peroxidase (GPX), and protease in both okra varieties (Noori and Sabzpari). Foliar application of α-Toc significantly improved the yield in tested okra varieties by increasing the activity of antioxidants (CAT, GPX, SOD, and ascorbic acid), accumulation of GB, and total free proline in fruit tissues under saline and non-saline conditions. Moreover, α-Toc application as a foliar spray alleviated the adverse effects of salt stress by reducing Na+ concentration, MDA, and H2O2 levels and improving the uptake of K+ and Ca2+. Among the tested okra varieties, Noori performed better than Sabzpari across all physio-biochemical attributes. Of all the foliar-applied α-Toc levels, 200 mg L−1 and 300 mg L−1 were more effective in the amelioration of salinity-induced adverse effects in okra. Thus, we concluded that higher levels of α-Toc (200 mg L−1 and 300 mg L−1) combat salinity stress more effectively by boosting the antioxidant potential of okra plants.

Quality Responses of Table Grapes ‘Flame Seedless’ as Effected by Foliarly Applied Micronutrients

“…Such an increase in sugar contents of grape berries could be related to the increased chlorophyll contents and the higher photosynthesis rate achieved through supplemental sprays of Fe, B and Zn [51]; similar findings were reported in apple and grapevines [52][53][54]. Higher sugar contents as a result of foliar sprays of micronutrients have also been reported in strawberry, pomegranate, and grapes [55][56][57].…”

Physiological, Biochemical, and Yield Responses of Linseed (Linum usitatissimum L.) in α-Tocopherol-Mediated Alleviation of Salinity Stress

“…Salinity effects could be alleviated by employing shot-gun approaches, that is, exogenous application of vitamins, nutrients, and antioxidants. One of these antioxidants is α-tocopherol, which can be exogenously applied as it is produced by plants endogenously (Naqve et al, 2021b). In this study, reduction in linseed has been alleviated by foliar spray of α-tocopherol.…”

“…Such treatments may be applied as foliar spraying or presowing seed treatment; alternatively, they may be applied to the growth medium (Hasanuzzaman et al, 2020). Tocopherol (α, β, γ, or δ) is a natural, highly liposoluble antioxidant produced by green photosynthetic organisms (Chen et al, 2016;Naseer et al, 2020), which effectively protects biological membranes from salinity-induced oxidation (Naqve et al, 2021b). α-Tocopherol restores plant growth by detoxifying singlet oxygen species and peroxides, thereby shielding photosystems, and inhibiting lipid peroxidation under saline conditions (Zandi and Schnug, 2022).…”

Chemical priming enhances plant tolerance to salt stress

“…Tocopherols belonging to the vitamin E group are biosynthesized by plants and regulate plant abiotic stress tolerance as an antioxidant and signaling molecule ( Ali et al, 2022 ). Naqve et al (2021) evaluated the impact alpha-tocopherol on salt-stressed okra [ Abelmoschus esculentus (L.) Moench] and observed an improvement in growth and yield via increasing the activity of antioxidants and via accumulation of Pro and GB. Moreover, the authors observed that alpha-tocopherol eased the hostile effects of salt stress by decreasing Na + uptake, MDA, and H 2 O 2 levels while boosting the uptake of K + and Ca 2+ .…”