Nitrogen-Doped Carbon Dots Increased Light Conversion and Electron Supply to Improve the Corn Photosystem and Yield

Abstract

Fluorescent carbon dots (CDs) have been reported as an artificial antenna to amplify the harvesting ability of light and enhance photosynthesis in plants. However, the main mechanism of this promotive effect and contributions of CDs’ structure are unclear. Herein, CDs and nitrogen (N)-doped CDs (N-CDs) with blue fluorescence were synthesized, and they could promote photosynthesis and growth of corn at an application concentration of 50 mg·L–1 or lower, compared to the control. Foliar application of N-CDs (5 mg·L–1) on corn could increase the net photosynthesis rate (21.51%), carbohydrate content (66.43% in roots and 42.03% in shoots), fresh weight (24.03% in roots and 34.56% in shoots), and dry weight (72.30% in roots and 55.75% in shoots), which were much higher than those of CDs. Principal component analysis and density functional theory calculation demonstrated that, compared with undoped CDs, N doping enhanced the light conversion and electron supply via altering the structure of CDs, making N-CDs effective light conversion materials and electron donors to promote the photoelectron transfer rate. Furthermore, foliar application of N-CDs could increase the yield and 1000-grain weight by 24.50 and 15.03%, respectively. Therefore, the application of N-CDs could be a promising approach for increasing agricultural production.

Carbon dots can strongly promote photosynthesis in lettuce (Lactuca sativa L.)

“…In these studies, the investigators studied the impacts of CDs on photosynthesis mainly by directly applying CDs to chloroplasts, [7][8][9] seed priming 10 or foliar spraying. 11,13 However, little information is available on whether root applied CDs can enhance photosynthesis in leaves after translocating from plant roots to leaves through vascular system. Recent studies mainly focused on the roles of CDs in promoting growth of plants.…”

The role of fluorescent carbon dots in crops: Mechanism and applications

“…A recent study has shown that N-doping blue-emitting CDs could increase maize yield by 24.5%. 40 Further studies have shown that N-doping can increase the electron density and forbidden bandwidth of CDs compared to undoped CDs, and reduce the recombination efficiency of electron hole pairs, thus providing electrons to the photosystem as electron donors. The net photosynthetic rate was increased by accelerating electron mobility.…”

“…Published studies on precursors, synthesis methods, quantum yields, absorption and emission wavelengths, crop species, and mechanisms of CDs are summarized in Table 1. 32,34,[39][40][41][42][43][44][45][46] Next, we will discuss the influence of PL color of CDs on photosynthesis.…”

“…CDs have excellent light‐harvesting ability and can be used as artificial photo‐antennae to absorb UV light that plants cannot absorb, and convert them into blue‐violet or red light that plants can use to increase the photosynthetic rate of leaves, thereby promoting plant growth. Published studies on precursors, synthesis methods, quantum yields, absorption and emission wavelengths, crop species, and mechanisms of CDs are summarized in Table 1 32,34,39–46 . Next, we will discuss the influence of PL color of CDs on photosynthesis.…”

“…By upregulating the expression of chlorophyll synthesis and metabolism‐related enzymes gene in rice, chlorophyll content and Rubisco activity were increased, and the fresh biomass of rice was increased by 70.60%. A recent study has shown that N‐doping blue‐emitting CDs could increase maize yield by 24.5% 40 . Further studies have shown that N‐doping can increase the electron density and forbidden bandwidth of CDs compared to undoped CDs, and reduce the recombination efficiency of electron hole pairs, thus providing electrons to the photosystem as electron donors.…”