Foliar L-Ascorbic Acid (Vit-C) Application Enhances Antioxidant Defense and Alleviates Heat- Induced Oxidative Stress in Wheat (Triticum aestivum L.) Genotypes
Priyanka Sharma
Department of Crop Physiology, Assam Agricultural University (AAU), Jorhat 785013, Assam, India and Department of Plant Physiology, Institute of Agricultural Sciences, Banaras Hindu University (BHU), Varanasi 221 005, Uttar Pradesh, India.
Gali Suresh
*
Department of Plant Physiology, Institute of Agricultural Sciences, Banaras Hindu University (BHU), Varanasi 221 005, Uttar Pradesh, India and Department of Botany and Plant Physiology, Chaudhary Charan Singh Haryana Agricultural University (CCS HAU), Hisar 125004, India.
Pravin Prakash
Department of Plant Physiology, Institute of Agricultural Sciences, Banaras Hindu University (BHU), Varanasi 221 005, Uttar Pradesh, India.
Asha Kumari
ICAR-Indian Agricultural Research Institute (ICAR-IARI), Gauria Karma, Hazaribagh 825405,Jharkhand, India.
Vinay Pratap Singh
Plant Physiology, ABV, COA, Khurai, District Sagar (JNKVV, Jabalapur), India.
Basant Kumar Dadrwal
*
Department of Plant Physiology, Sri Karan Narendra Agriculture University (SKNAU), Jobner 302024, Rajasthan, India.
Madisetty Sai Venkata Ravi Teja
Department of Crop Physiology, University of Agricultural Sciences (GKVK), Bengaluru 560065, Karnataka, India.
*Author to whom correspondence should be addressed.
Abstract
High temperature stress disrupts cellular metabolism in plants by increasing the accumulation of reactive oxygen species (ROS) resulting in oxidative injury and impaired physiological function. This study investigated the mitigative role of foliar-applied L-ascorbic acid (Vit-C) in two contrasting wheat genotypes HUW-510 (heat-tolerant) and HUW-468 (heat-susceptible) subjected to normal and late-sown heat stress conditions. Heat stress significantly elevated ROS levels by 35–55%, while reducing chlorophyll content (20–30%), nitrate reductase activity (18–28%), total protein (25–35%), membrane stability index (MSI) and relative water content (RWC) indicating marked oxidative and metabolic impairment. Activities of key antioxidant enzymes catalase (CAT), superoxide dismutase (SOD) and ascorbate peroxidase (APX) also declined under heat stress suggesting suppression of the enzymatic defense system.
Foliar application of L-ascorbic acid at 1.0, 5.0 and 10.0 mM substantially alleviated oxidative stress with 10.0 mM exhibiting the strongest mitigative effect. Ascorbic acid reduced ROS accumulation by 25–35%, enhanced CAT, SOD and APX activities by 30–50%, improved chlorophyll and NR activity and increased osmolyte levels (proline and soluble sugars). The tolerant genotype HUW-510 consistently displayed superior antioxidant recovery compared to HUW-468 demonstrating genotype-specific responsiveness to AA. Overall L-ascorbic acid effectively strengthened antioxidant defense, stabilized cellular metabolism and mitigated heat-induced oxidative damage highlighting its potential as a practical strategy for improving thermotolerance in wheat.
Keywords: Antioxidant defense, Ascorbate peroxidase (APX), Catalase (CAT), heat stress, L-ascorbic acid (Vit C), Nitrate reductase (NR), oxidative stress, proline, Reactive oxygen species (ROS), Soluble sugars, Superoxide dismutase (SOD)