Next generation quantum dot nanofertilizers for sustainable agriculture and soil microbial functionality

Quantum dots (QDs) are emerging as functional nanomaterials with increasing relevance to environmentally sustainable agricultural systems. Conventional chemical fertilizers contribute substantially to nutrient leaching, soil degradation, and water pollution, highlighting the need for alternative fertilization strategies that sustain crop productivity while reducing environmental burdens. In this study, QD-based nanofertilizers were evaluated as a next-generation approach to improve crop performance and soil biochemical functionality. Tomato plants ( Solanum lycopersicum ‘Natavi F1’) were cultivated in Inceptisol soil under controlled conditions using conventional NPK fertilization and QD nanofertilizer treatments, including carbon quantum dots (CQDs) and nitrogen-doped carbon quantum dots (CNQDs) with nitrogen contents of 25% (hereafter referred to as CNQD-N25) and 46% (hereafter referred to as CNQD-N46). Fertilizers were applied in three split doses at 20-day intervals to promote synchronized nutrient availability and minimize nutrient losses. Compared with conventional fertilization, which produced no tomato fruit, QD nanofertilizers yielded 198.5 g of tomato fruit per plant at the early fruiting stage and increased plant height, leaf number, and shoot diameter by 39.22%, 79.21%, and 11.36%, respectively, at the early vegetative stage. Soil enzymatic activities were also significantly enhanced, with dehydrogenase, cellulase, and fluorescein diacetate (FDA) hydrolase activities increasing by 57.08%, 473.72%, and 53.03%, respectively, relative to the conventional fertilizer treatment. In parallel, CQD and CNQD-N25 treatments increased the abundance of Azospirillum spp. and decomposer communities in the rhizosphere, indicating an improvement in soil microbial functional diversity that is consistent with the observed stimulation of soil enzyme activities. FTIR analysis further indicated interactions between QDs and soil microbial functional groups, suggesting favorable compatibility of these nanomaterials within the soil matrix. Overall, the results demonstrate that QD-based nanofertilizers can improve tomato productivity while enhancing soil microbial and biochemical functionality, highlighting their potential as environmentally relevant alternatives to conventional fertilizers. Nevertheless, further studies are required to evaluate their long-term environmental fate and safety before wider agricultural application.