Promotion effect of nitrogen-doped functional carbon nanodots on the early growth stage of plants

The objective of this paper is to study the effects of nitrogen-doped functional carbon nanodots (N-FCNs) on the early growth stage of plants. Hydrosoluble and biocompatible N-FCNs with high content of available N (ammonium and amino groups) and carboxyl groups are synthesized by a super green electrochemical method. N-FCNs universally express good eurytopic influence on different species of plants by inducing seeds germination, promoting root development, biomass accumulation, root cell length, chlorophyll level and transpiration of young seedlings. When functional carbon nanodots without N doping (FCNs) promote tomato and corn seeds germination rate by 92.4% and 76.2% maximally, N-FCNs could further improve the germination rate by about 17.0% and 25.5%. N-FCNs can even significantly raise the green vegetable (pakchoi) yield to 2.1 and 1.4 times on the 18th and 30th day. Leaf chlorophyll content is also increased to 1.36 and 1.55 times compared with FCNs treated group and the control group, respectively. The promotion effect of the nanodots is apparently depended on their composition, nanostructure, as well as plant species and age. Nanoscale structure and abundant hydrophilic functional groups can enable N-FCNs regulating the seed germination and plant growth by promoting the uptake and transportation of water and nutrients. The accumulation and transport of N-FCNs are investigated, which reveals N-FCNs are friendly to cells because they are absorbed and transported through nonprotoplast pathway in plant. As a result, N-FCNs have great potential for horticulture application as a biocompatible nano-medium to regulate both metabolism and early development of plants.