EVALUATING MICRONUTRIENTS AND TOXIC ELEMENTS IN RICE (ORYZA SATIVA) UNDER ALTERNATE WETTING AND DRYING (AWD) USING CONTROLLED GROWTH CHAMBER EXPERIMENTS

Rice (Oryza sativa), a dietary cornerstone for billions globally, plays a critical role in micronutrient security, particularly in the Global South, where malnutrition and contamination risks converge. Building on prior field research, this study investigates the effects of alternate wetting and drying (AWD) irrigation on micronutrient availability (Fe, Mg, Cu, Zn) and the mitigation of toxic element accumulation (As, Cd) in rice grains. Controlled growth chamber experiments provided tightly regulated conditions for comparing clay loam rice paddy soil from Arkansas with silty clay loam soil from New York, simulating both AWD and flooded controls. The arsenic-resistant Cocodrie cultivar was planted using direct-seeding and pre-germinated transplanting methods. Soil moisture, air and soil temperature, and CO₂ concentrations were continuously monitored. Weekly porewater samples were collected, filtered, and analyzed for elemental composition and arsenic speciation. Drying cycles simulated AWD, and biomass and mature rice grains were digested for elemental analysis to assess nutrient dynamics and contaminant mobility. Preliminary results indicate that soil type and irrigation strategy significantly shape porewater chemistry, with AWD reducing arsenic accumulation in rice grains and enhancing micronutrient availability, particularly in silty clay loam soils. These findings demonstrate the potential of AWD to improve nutritional quality while mitigating toxic risks in rice cultivation. This research highlights the value of sustainable irrigation practices for global food security. By further exploring the interplay between soil type, irrigation strategy, and elemental dynamics, this study provides a framework for optimizing rice production under changing environmental conditions. Future work will focus on refining AWD protocols to enhance rice nutritional quality and minimize contaminant risks.