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.

The key algal response mechanisms to cope with NP toxicity and implications for algal bloom control by NPs.

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This study explores ibuprofen (IBP) uptake and transformation in the wetland plant species Phragmites australis and the underlying mechanisms. We grew P. australis in perlite under greenhouse conditions and treated plants with 60 μg/L of IBP. Roots and rhizomes (RR), stems and leaves (SL), and liquid samples were collected during 21 days of exposure. Results show that P. australis can take up, translocate, and degrade IBP. IBP was completely removed from the liquid medium after 21 days with a half-life of 2.1 days. IBP accumulated in RR and was partly translocated to SL. Meanwhile, four intermediates were detected in the plant tissues: hydroxy-IBP, 1,2-dihydroxy-IBP, carboxy-IBP and glucopyranosyloxy-hydroxy-IBP. Cytochrome P450 monooxygenase was involved in the production of the two hydroxy intermediates. We hypothesize that transformation of IBP was first catalyzed by P450, and then by glycosyltransferase, followed by further storage or metabolism in vacuoles or cell walls. No significant phytotoxicity was observed based on relative growth of plants and stress enzyme activities. In conclusion, we demonstrated for the first time that P. australis degrades IBP from water and is therefore a suitable species for application in constructed wetlands to clean wastewater effluents containing IBP and possibly also other micropollutants.