Wastewater irrigation impacts on seed germination and seedling growth of rice (Oryza sativa), tomato (Solanum lycopersicum), and mustard (Brassica napus) crops†

Wastewater, particularly industrial water, is being utilised to irrigate agricultural fields owing to the scarcity of freshwater for irrigation. In the present experiment, irrigation wastewater was collected from three different agriculture farms in the Sylhet region of Bangladesh, and their suitability for seed germination and the growth performance of rice (Oryza sativa), tomato (Solanum lycopersicum), and mustard (Brassica napus) crops were evaluated. Biochemical analysis revealed that untreated irrigation wastewater (UTW) contained the heavy metals Cd, Cr, Cu, Ni, Pb and Zn at moderate toxicity levels and Ca and Fe at higher toxicity levels. Consequently, wastewater irrigation showed a significant inhibitory effect on seed germination and seedling growth performance (biomass accumulation and root/shoot length ratio) in all crop varieties and regions. Additionally, wastewater irrigation increased seedling mortality by approximately 10–30% and elevated levels of H₂O₂, electrolyte leakage (EL), and malondialdehyde (MDA) in all crop species, indicating enhanced reactive oxygen species (ROS) accumulation. Similarly, industrial wastewater treatment showed inhibitory effects on antioxidant content together with high oxidative stress, reflecting adverse impacts on seed germination and seedling growth.