Open Access

ARTICLE

Appraisal of Improvement in Physiological and Metabolic Processes by Exogenously Applied Natural and Synthetic Ascorbic Acid in Okra (Abelmoschus esculentus L.) Fruit Subjected to Water Deficit Stress

by Muhammad Younis¹, Nudrat Aisha Akram^1,*, Arafat Abdel Hamed Abdel Latef^2,*, Muhammad Ashraf³

1 Department of Botany, Government College University, Faisalabad, 38000, Pakistan
2 Department of Botany and Microbiology, Faculty of Science, South Valley University, Qena, 83523, Egypt
3 Department of Botany, University of Lahore, Lahore, Pakistan

* Corresponding Authors: Nudrat Aisha Akram. Email: ; Arafat Abdel Hamed Abdel Latef. Email:

Phyton-International Journal of Experimental Botany 2023, 92(10), 2761-2784. https://doi.org/10.32604/phyton.2023.028801

Received 08 January 2023; Accepted 16 June 2023; Issue published 15 September 2023

Abstract

To counteract the effects of drought stress, scientists have adopted several approaches including the use of different chemicals both inorganic and organic, which is contemplated as a highly efficient and cost-effective shot-gun approach. Ascorbic acid (AsA) is a potential organic substance, which widely occurs in plants, and is considered to be an effective antioxidant to counteract reactive oxygen species (ROS). Thus, a pot experiment was performed to assess the relative mitigating impacts of synthetic AsA and naturally occurring AsA in the form of lemon juice (LJ) and orange juice (OJ) on two cultivars of okra (Abelmoschus esculentus L.) namely Sabz Pari and Bhindi Sanwali under varying water deficit conditions. After 30 days of seed germination, okra seedlings were subjected to different irrigation regimes, i.e., water deficit stress [(65% and 50% F.C.) and control conditions (100% F.C.)]. Different levels of AsA [control (no spray), 14 mg L⁻¹ LJ, 24 mg L⁻¹ OJ and 150 mg L⁻¹ AsA] obtained from different sources were applied as a foliar spray to control and water-stressed plants. Drought stress prominently reduced plant growth and yield attributes of the okra cultivars. Water-deficit conditions (65% and 50% F.C.) substantially decreased the fruit chlorophyll (a, b) pigments and the activity of superoxide dismutase (SOD) enzyme, while an increase was observed in the contents of fruit’s hydrogen peroxide (H₂O₂), malondialdehyde (MDA), total phenolics, total soluble sugars, AsA, and total soluble proteins. Drought stress also increased the activities of antioxidant enzymes like peroxidase (POD) and catalase (CAT). However, plant growth and yield attributes, fruit chlorophyll pigments, total phenolics, total soluble sugars, total free amino acids, total soluble proteins, AsA, GB, H₂O₂, and the activities of antioxidant enzymes (POD and CAT) were increased by the AsA exogenous treatment in both okra cultivars under water deficit and control conditions. Overall, LJ and OJ were more effective than the synthetic AsA in upregulating the physiological and metabolic processes of okra plants. So, cost-effective as well as multi-nutrient natural sources of AsA could be suggested for alleviating the harmful effects of water deficit stress on plants.

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