Phytotoxicity effect study on Vigna radiata as affected by variation of palm oil mill effluent (POME) concentrations

The palm oil industry is a major source of water pollution in Southeast Asia. Its wastewater normally contains a complex mixture of organic matter and is high in chemical oxygen demand, biochemical oxygen demand and suspended solids. Thus, this study aims to screen the phytotoxic effects of different concentrations of palm oil mill effluent (POME). The phytotoxicity of POME was studied using mung beans (Vigna radiata), whereby the seedling growth and germination were monitored. In this study, mung beans were allowed to germinate under hydroponics conditions in different concentrations of POME solution. The relative root length, shoot length, percentage of germination and the germination index were evaluated. After 5 days of germination, results from phytotoxicity analysis suggest that the seedling growth declined with the increase in concentration of POME solution. POME at a concentration of 100% (v/v) has resulted in the worst seedling growth condition with 60% of seed germination, null shoot length, root elongation at 1.02 cm, wet biomass at 0.19 g and the lowest germination index at 7.98%. Mung beans might have experienced stress conditions due to the excessive amount of complex and highly biodegradable organic matter and pollutants in POME which stunted the growth of plants. Overall, phytotoxicity assessment of POME using V. radiata as a plant receptor is such a simple technique and applicable to evaluate the effect of chemical pollution of effluent on seed growth.