Comparative Effectiveness of Iodine Nanoparticles and Potassium Iodide on Nitrogen Assimilation, Biomass, and Yield in Lettuce

Efficient nitrogen assimilation in crops remains a priority for sustainable agriculture. This study evaluated the effects of foliar iodine nanoparticles (INPs) on nitrogen metabolism, yield, and physiological performance in Lactuca sativa L. cv. Butterhead, in comparison with potassium io-dide (KI). Plants were treated with INPs and (KI) at concentrations of 40, 80, and 160 µM under a passive hydroponic system. Results showed that INPs at 40 µM significantly enhanced total bi-omass and soluble amino acid content compared to the control, without inducing phytotoxic ef-fects on photosynthetic pigments. While yield differences were not statistically significant, INPs promoted favorable biochemical responses, particularly in nitrogen-related metabolism, sug-gesting a more efficient nutrient utilization. (KI) treatments increased nitrate reductase activity and soluble protein levels yet did not outperform INPs in biomass accumulation. These findings indicate that iodine delivered in nanoparticulate form may offer a sustained, low-dose alterna-tive for improving nitrogen use efficiency, without adverse effects on plant physiology. The study supports the use of INPs as a promising strategy for enhancing nitrogen assimilation and biochemical quality in leafy vegetables, contributing to the development of precision fertiliza-tion technologies within sustainable nitrogen management systems.