Response of Soybean Plants to the Foliar Application of Carbon Quantum Dots Under Drought Stress: A Field Study

Drought stress may be mitigated by the high electron transfer capability of carbon quantum dots, effectively improving the growth and physiological efficiency of plants under stress. Accordingly, a two-year field experiment was conducted to examine the effects of carbon quantum dots on physiological efficiency of soybean plants under drought stress. The carbon quantum dots were applied as a foliar treatment at a concentration of 5 mg L⁻¹ on soybean plants under normal and water-stress conditions. The results showed that the application of carbon quantum dots did not have a noticeable impact on the physiological performance of plants under regular irrigation. However, under drought stress, carbon quantum dots significantly improved various parameters, including soybean ground green cover (about 14%), leaf area (21%), chlorophyll content (18%), maximum efficiency of photosystem II (19%), relative photosynthetic electron transport rate (23%), leaf water content, osmolyte production, antioxidative activities, and grain yield (25%). Additionally, carbon quantum dots reduced the generation of reactive oxygen species, lipid peroxidation, and osmotic stress during drought conditions. These findings suggest that carbon quantum dots can protect plant cells from oxidative and osmotic damage, thereby enhancing physiological performance during periods of drought stress. These results reveal the potential of CQDs as a promising tool for enhancing drought tolerance in soybean plants, with implications extending beyond this crop. The mechanistic insights highlighted the broader applicability of CQD treatments in agriculture, offering a novel strategy to mitigate drought stress across diverse crop species. Our study also offers tangible benefits for farmers and researchers, paving the way for sustainable crop management practices in the face of climate change-induced challenges.