Foliar Application of Carbon Quantum Dots Photosynthesis Enhancer for Enhancing the Growth and Development of Green Mustard (Brassica Juncea) in Indoor Hydroponics

Abstract

Sustainable agriculture faces significant challenges in enhancing crop yields while reducing chemical inputs and adapting to climate variability. This study investigates the potential of carbon quantum dots (CQDs) as photosynthesis enhancers in hydroponically grown green mustard (Brassica juncea). CQDs, zero-dimensional nanomaterials functioning as artificial photosynthetic pigments, were applied as foliar sprays at concentrations ranging from 0 to 400 ppm. The study evaluated both morphological parameters and photosynthetic efficiency metrics under different lighting conditions. Results demonstrated that treatment with 150 ppm CQDs significantly enhanced plant growth, increasing CO₂ assimilation rate and Rubisco activity by 58% and 33% respectively, compared to controls. This concentration also exhibited the highest intrinsic water use efficiency (iWUE), indicating optimal water utilization during photosynthesis. The study further examined CQDs' performance under white light versus red/blue (R/B) light combinations, analyzing chlorophyll fluorescence (Fv/Fm), effective quantum yield (ΦPSII), and light response curves. Results revealed that CQDs function differently under various light spectra, acting primarily as light converters under white light and as photosensitizers under R/B light. Electron transfer mechanisms in the CQDs/chloroplast complex were elucidated through spectroscopic analysis, providing insights into the fundamental interactions driving enhanced photosynthetic efficiency. This comprehensive investigation demonstrates the significant potential of CQDs for improving agricultural productivity through enhanced photosynthetic efficiency, particularly in controlled environment agriculture.

Keywords: Carbon quantum dots, growth, photosynthesis parameters, electron transfer mechanism, green mustard