Synergistic role of potassium fertilizer and kinetin in mitigating iron toxicity and enhancing yield in lowland rice

Lowland rice in humid Asian regions is prone to iron toxicity. High Fe²⁺ in the soil can reduce yield by 12-100% depending on genotype, stress severity, and soil fertility. Accordingly, two years of field experiment coined with split-plot design was conducted during the wet seasons of 2022 and 2023 at the Central Farm, Odisha University of Agriculture and Technology, Bhubaneswar. Where three replicated plots with five rice genotypes as main, while subplots received five K fertilizer levels with or without foliar kinetin (200 mg/L). Percent yield increased with both sole K application (62.42%-72.85%) and combined K with kinetin (86.39%-113.36(%), indicating that K alone was insufficient to overcome iron toxicity. Kinetin enhanced sink capacity and promoted efficient translocation of photosynthates into filled grains, improving grain weight per panicle. Increasing K doses with kinetin improved morphological traits, photosynthetic pigments, and translocation of proteins and carbohydrates from source to sink. The combined treatment alleviated Fe toxicity by limiting Fe uptake, reducing ROS, MDA, proline, and phenolics and regulating antioxidant enzyme activity. Tejaswini, treated with 100-120 kg K₂O/ha and two kinetin sprays, achieved the highest yield gains (110-113%), demonstrating its potential for sustainable rice production in iron-toxic lowlands.