Genetic Diversity and Tolerance Assessment of Rice Varieties to Mercury Contamination in Illegal Gold Mining Affected Areas: A Case Study in Mandailing Natal Regency, North Sumatra, Indonesia

Abstract

Objectives: This study aims to identify rice varieties that accumulate low levels of mercury during the early vegetative growth phase. The research focuses on the toxic effects of mercury on plants, mechanisms of mercury absorption, and the concepts of environmental pollution and phytoremediation. It also examines theories of bioaccumulation and genetic variability in plant responses to heavy metal stress.   Methods: The study utilized a Randomized Complete Block Design (RCBD) with two factors: 23 rice varieties and two mercury concentration levels (0 mg HgCl2 and 60 mg HgCl2). Mercury content in roots, stems, and leaves was measured using a UV-Vis spectrophotometer. Data were analyzed using variance analysis to determine the effects of variety and mercury concentration.   Results: Results indicated significant genetic variation in plant height among the rice varieties, unaffected by mercury concentration. The local variety Siganteng showed the highest plant height. Mercury stress significantly reduced root length, with IF 16 exhibiting the highest tolerance and Sigudang the lowest. The relative root length categorized varieties into tolerant, moderate, and sensitive groups, highlighting genetic diversity in response to mercury contamination.   Conclusion: This research provides insights into selecting rice varieties with high tolerance to mercury for cultivation in contaminated areas, thereby reducing the risk of mercury exposure to consumers and enhancing agricultural sustainability. The study contributes to the literature by identifying rice varieties with low mercury accumulation and high tolerance, offering practical solutions for farmers in mercury-contaminated regions. The findings have significant implications for food safety and environmental health in areas affected by illegal gold mining activities.