Pallvi Singh1, Awanish2 and Parikshit Kumar Singh3
1 & 2- Department of Botany, Mahatma Gandhi P G College, Gorakhpur, Uttar Pradesh, India
3-Department of Botany, Digvijay Nath P.G. College, Gorakhpur, Uttar Pradesh, India
Corresponding Author- Prof. Awanish, E Mail: drawanish@gmail.com,
Mobile Number: 9412395081, Orcid Id – 0009-0009-5156-0810
Abstract
The biochemical responses of plants to wastewater irrigation reflect the complex interplay between nutrient enrichment and contaminant-induced stress. This study investigated the effects of irrigation with heavy metal-contaminated water from Ramgarh Lake, Gorakhpur, on photosynthetic pigments, stress-related metabolites, and primary metabolic compounds in tomato (Solanum lycopersicum L. cv. Mahyco NO.63 F1 Hybrid). A two-year pot experiment (2024–2025) compared tap water irrigation (control) with raw wastewater from the lake’s outflow channel. Polluted water irrigation significantly enhanced photosynthetic pigment concentrations, with chlorophyll a increasing by 34.9%, chlorophyll b by 41.2%, and total chlorophyll by 36.7%. Carotenoid content rose by 38.3%, indicating improved photosynthetic capacity. Stress-adaptive metabolites showed substantial increases: proline by 109.6%, anthocyanin by 73.3%, total phenolics by 51.1%, and ascorbic acid by 36.7%. Primary metabolites in fruits also increased, with carbohydrates rising by 31.7% and proteins by 46.7%. These biochemical changes demonstrate that tomato plants mounted a coordinated physiological response to wastewater irrigation, simultaneously benefiting from nutrient enrichment while activating protective mechanisms against heavy metal-induced oxidative stress. The findings highlight the remarkable physiological plasticity of tomato under moderate contamination stress and provide insights for managing wastewater-irrigated vegetable production.
Keywords: Solanum lycopersicum, wastewater irrigation, photosynthetic pigments, antioxidant metabolites, proline, heavy metal stress, oxidative stress