Graphene oxide (GO), as a novel carbon-based nanomaterial (CBN), has been widely applied to every respect of social life due to its unique composite properties. The widespread use of GO inevitably promotes its interaction with heavy metal cadmium (Cd), and influences its functional behavior. However, little information is available on the effects of GO on greening hyperaccumulators under co-occurring Cd. In this study, we chose a typical greening hyperaccumulator (Lonicera japonica Thunb.) to show the effect of GO on Cd accumulation, growth, net photosynthesis rate (P_n), carbon sequestration and oxygen release functions of the plant under Cd stress. The different GO-Cd treatments were set up by (0, 10, 50 and 100 mg L⁻¹) GO and (0, 5 and 25 mg L⁻¹) Cd in solution culture. The maximum rate of Cd accumulation in the roots and shoots of the plant were increased by 10 mg L⁻¹ GO (exposed to 5 mg L⁻¹ Cd), indicating that low-concentration GO (10 mg L⁻¹) combined with low-concentration Cd (5 mg L⁻¹) might stimulate the absorption of Cd by L. japonica. Under GO treatments without Cd, the dry weight of root and shoot biomass, P_n value, carbon sequestration per unit leaf area and oxygen release per unit leaf area all increased in various degrees, especially under 10 mg L⁻¹ GO, were 20.67%, 12.04%, 35% and 28.73% higher than the control. Under GO-Cd treatments, it is observed that the cooperation of low-concentration GO (10 mg L⁻¹) and low-concentration Cd (5 mg L⁻¹) could significantly stimulate Cd accumulation, growth, photosynthesis, carbon sequestration and oxygen release functions of the plant. These results indicated that suitable concentrations of GO could significantly alleviate the effects of Cd on L. japonica, which is helpful for expanding the phytoremediation application of greening hyperaccumulators faced with coexistence with environment of nanomaterials and heavy metals.

“Hormesis” is considered a dose–response phenomenon mainly observed at hyperaccumulator plants under heavy metals stress. In this study, the effects of electric fields on hormesis responses in Lonicera japonica Thunb. under cadmium (Cd) treatments were investigated by assessing the plant growth and photosynthetic characteristics. Under Cd treatments without electric fields, the parameters of plant growth and photosynthetic characteristics increased significantly when exposed to 5 mg L⁻¹ Cd, and decreased slightly when exposed to 25 mg L⁻¹ Cd, showing an inverted U-shaped trend, which confirmed that low concentration Cd has a hormesis effect on L. japonica. Under electric fields, different voltages significantly promoted the inverted U-shaped trend of the hormesis effect on the plant, especially by 2 V cm⁻¹ voltage. Under 2 V cm⁻¹ voltage, the dry weight of the root and leaf biomass exposed to 5 mg L⁻¹ Cd increased significantly by 38.38% and 42.14%, and the photosynthetic pigment contents and photosynthetic parameters were also increased significantly relative to the control, indicating that a suitable electric field provides better improvements for the hormesis responses of the plant under Cd treatments. The synergistic benefits of the 5 mg L⁻¹ Cd and 2 V cm⁻¹ electric field in terms of the enhanced hormesis responses of growth and photosynthetic characteristics could contribute to the promoted application of electro-phytotechnology.

In recent years, there has been a significant growth in scholarly attention to the effects of Cd stress on horticultural plants, as reflected by the abundance of research articles on this issue in academic publications. Therefore, it is necessary to conduct a review of current research and provide a comprehensive perspective to quickly grasp the latest developments and future trends in the research field of “horticultural plants-Cd responses”. By utilizing a visualizing bibliometric analysis software CiteSpace, this study integrated and analyzed a total of 4318 relevant research records—2311 from the Web of Science (WOS) database and 2007 from the China National Knowledge Infrastructure (CNKI) database—related to “horticultural plants-Cd responses”, covering the period from 1999 to 2024. A visual analysis was conducted in the form of knowledge mappings, including the current research status of “horticultural plants-Cd responses”, as well as the differences in publications’ temporal distribution, spatial distribution (cooperation networks) and intellectual base between China and foreign countries, precisely uncovering the core aspects of research topics related to the field. The results indicated the following: (1) Scientific research on “horticultural plants-Cd responses” has experienced a significant increase in publication volume and has entered a phase of rapid development. Globally, there has been an annual average increase of 217 articles in the WOS since 2019, while in China, the annual average increase has been 134 articles in the CNKI since 2015. (2) China is the most productive country in terms of publication volume (1165 articles, 52.79%), engaging in active partnerships with other countries worldwide. Chinese scholars (Lin L. and Liao M.) are leading researchers in both domestic and international research fields of “horticultural plants-Cd responses”. The network of collaborations among authors and institutions in the WOS database seemed denser compared to that in the CNKI database. (3) International research hotspots have focused on accumulation, tolerance and oxidative stress, while domestically, the focus has been on antioxidant enzymes, growth and seed germination. Phytoremediation, subcellular distribution and the transcriptome are the world’s emerging topics, while in China, growth and physiological characteristics are still emerging topics. (4) In comparison, China exhibited a lagging development trend, which is reflected in the fact that it began to focus on gene expression and transcriptome research only after the global frontier shifted towards biochar and cadmium co-stress and yield response. Based on these, this study provides a systematic theoretical basis for subsequent research on “horticultural plants-Cd responses”, aiding scholars in their efforts to understand the dynamic frontiers and address the challenges in this field.