Abstract
In this study, rice husk-based carbon quantum dots (RCQDs) were synthesized and characterized by using Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Fourier Transmission Infrared spectroscopy (FTIR), UV-visible spectroscopy, X-ray Diffraction (XRD), photoluminescence, zeta potential, and fluorescence lifetime analysis. The RCQDs synthesized were further identified to be spherical in shape with 5 nm size and were also amorphous with a strong photoluminescence at 410 nm, along with abundant oxygen-containing functional groups. Upon interaction with the rice seeds, the RCQDs were found to significantly enhance the seed germination, seedling vigor, and growth parameters. In addition, under the induced drought condition ( - 1.2 MPa PEG), the RCQD treated rice seedlings were found to have enhanced shoot (~ two fold) and root length, increased chlorophyll content, and a significant enhancement in the antioxidant activity when compared to the untreated controls. Further elemental analysis could demonstrate the improved mobilization of macronutrients and elevated uptake of key micronutrients such as sodium, zinc, and iron in rice due to RCQD treatment. The same was also observed to confer the resistance to rice from biotic stress caused by Xanthomonas oryzae and Rhizoctonia solani as evidenced by the reduced lesion development in the detached leaf assay monitored over a period of 5 days post-treatment. These bio-stimulatory and protective effects suggest the RCQDs to have multimechanistic effects in rice by promoting the plant growth and enhancing the tolerance to abiotic and biotic stress factors. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13205-025-04454-8.