Journal of Crop Production and Processing

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Faraji M, Andalib B, Silsepour M, Nasiri S. Evaluation of the Role of Ellagic Acid in Reducing Oxidative Stress in Pinto Bean (Phaseolus vulgaris L.) under Drought Stress Conditions. J Crop Prod Process. 2026; 16 (3) :63-77
URL: http://jcpp.iut.ac.ir/article-1-3413-en.html

Introduction: Drought stress is one of the major environmental factors limiting the growth and productivity of common bean (Phaseolus vulgaris L.). Water deficit disrupts physiological and biochemical processes by increasing the production of reactive oxygen species (ROS), leading to oxidative stress, membrane damage, and reduced photosynthetic efficiency. Although plants possess antioxidant defense systems, severe drought often exceeds their protective capacity. Therefore, the application of natural antioxidant compounds has emerged as an effective approach to enhance plant tolerance to drought stress. Ellagic acid is a naturally occurring phenolic compound with strong antioxidant activity that can scavenge free radicals and improve cellular protection against oxidative damage. However, information regarding its effectiveness in common beans under field conditions in drought-prone areas remains limited. This study was conducted to evaluate the effects of different application methods of ellagic acid on growth, antioxidant activity, membrane stability, and yield of common bean under varying levels of drought stress.

Materials and Methods: A two-year field experiment was carried out using a split-plot arrangement based on a randomized complete block design with three replications. Irrigation treatments were assigned to the main plots and included full irrigation (100% of crop water requirement), moderate drought stress (75% of crop water requirement), and severe drought stress (50% of crop water requirement). Subplots consisted of four ellagic acid treatments (50 mg L⁻¹): untreated control, seed priming, foliar application, and the combined application of seed priming and foliar spraying. Growth traits, including plant height, leaf number, and leaf area index, were recorded during the growing season. Electrolyte leakage was measured to evaluate membrane stability, while superoxide dismutase (SOD) activity was determined as an indicator of antioxidant response. Yield components, biological yield, and grain yield were measured at harvest. Data collected over the two growing seasons were analyzed using analysis of variance, and treatment means were compared at the 5% probability level.

Results: Drought stress significantly reduced vegetative growth, yield components, biological yield, and grain yield while increasing electrolyte leakage. Significant interactions between irrigation regime and ellagic acid application were observed for plant height, leaf number, leaf area index, electrolyte leakage, and grain yield. Application of ellagic acid significantly enhanced superoxide dismutase (SOD) activity under both well-watered and drought conditions, indicating improved antioxidant defense. The combined application of seed priming and foliar spraying produced the highest values of plant height, leaf area index, number of leaves, number of pods per plant, and grain yield under full irrigation. Conversely, untreated plants exposed to severe drought exhibited the lowest performance for all measured traits. Under moderate drought stress, foliar application was more effective than seed priming in reducing electrolyte leakage, whereas under severe drought, the combined treatment provided the greatest protection against membrane damage and resulted in higher grain yield. These findings indicate that the response of common bean to ellagic acid depends on both drought severity and the application method.

Discussion: The positive effects of ellagic acid can be attributed to its antioxidant properties, which enhance ROS scavenging and reduce oxidative damage under drought conditions. Increased SOD activity and reduced electrolyte leakage suggest improved membrane integrity and greater protection of cellular structures. These physiological improvements likely contributed to enhanced plant growth and higher yield under water-limited conditions. The superior performance of the combined seed priming and foliar application indicates that integrating pre-sowing treatment with foliar supplementation provides prolonged protection throughout plant development. In contrast, foliar spraying alone was sufficient to alleviate moderate drought stress by rapidly improving antioxidant capacity. These results support previous findings that exogenous antioxidants enhance drought tolerance through the maintenance of cellular homeostasis and protection of the photosynthetic apparatus.

Conclusions: Ellagic acid effectively alleviated drought-induced oxidative stress in common bean by enhancing antioxidant activity, reducing membrane injury, and improving plant growth and grain yield. Although all application methods were beneficial, their effectiveness varied with drought intensity. Foliar application was more efficient under moderate drought, whereas the combined application of seed priming and foliar spraying was superior under severe drought stress. These findings suggest that ellagic acid is a promising and environmentally friendly strategy for improving drought tolerance and maintaining common bean productivity under limited water availability. Further research should evaluate different application rates and investigate the physiological and molecular mechanisms underlying its protective effects.