Applications of Carbon Dots in Agriculture: Synthesis, Functionalization, and Plant Interaction Mechanisms

Abstract Carbon dots (CDs) are an emerging carbon-based nanomaterial with steadily increasing prospects across agricultural applications, which is mostly due to their easy synthesis, functionalization, small particle size, high biocompatibility, low toxicity, and peculiar optical properties. However, existing studies have largely focused on individual functions or localized mechanisms, with insufficient attention paid to the systemic relationships among material design, functional expression, and plant response. Therefore, this paper adopts a cross-scale perspective to provide a systematic review of the synthesis strategies, functionalization designs, and interaction mechanisms of CDs with plants in agricultural applications. This article also summarizes biomass-based green synthetic methods, highlighting the advantages of simple and scalable approaches, such as hydrothermal and microwave methods in agricultural applications, and further outlines the principles of functionalization design based on the regulation of surface functional groups. The study focuses on the synergistic role of CDs in multifunctional applications, such as promoting nutrient utilization, enhancing stress resistance, and enabling the detection of endogenous plant signals, and proposes their potential role as a multifunctional agricultural nanoplatform. The fundamental interaction mechanisms between CDs and plants, including their absorption, distribution, and transport via the symplastic and apoplastic pathways, are addressed, and emphasize the fundamental links connecting these different processes to real-world agricultural applications. In summary, the recent advances and innovations offer novel strategies for efficient crop yield enhancement, and this review aims to serve as a guide toward targeted design and precise application of high-performance CDs tailored to agricultural needs.