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Crop yield increases with a sustained increase in leaf photosynthesis. Due to many limitations, plants do not sufficiently use their photosynthetic capacity. Carbon dots (CDs) have a high light harvest capability, which may be used to improve the photosynthesis efficiency of plants. In this study, nontoxic orange CDs (o-CDs) were foliarly applied to boost the maize (Zea mays L.) and green beans (Phaseolus vulgaris L.) productivity in the field. Leaves of both plant species were sprayed three times with 1 and 5 mg/L of the o-CDs aqueous solutions in equal intervals during the vegetative growth stage until flowering. To find the best geometries for CO2 adsorption on o-CD, modeling of o-CDs-CO2 interaction was performed. Photosynthesis parameters and fruit yield were measured during plant growth. Total phenolic content and antioxidative activity were monitored as oxidative stress indicators. Computational simulations and spectroscopic measurements suggest that o-CDs, acting as a "CO2 delivery" system, can enhance photosynthetic efficiency. Photosynthesis was enhanced in both plant species, but only green beans showed an increased fruit yield. CO2 use in tested species was discussed in light of two mechanisms. Plant species show different, but no significant antioxidative responses. The chemical surface composition has shown that o-CDs were not contained in either the leaves or fruits of the treated plants. The results indicate that o-CDs may be applied as a simple and safe biostimulator on plants. That could have an environmental benefit in capturing CO2 in the atmosphere. [ABSTRACT FROM AUTHOR]

Urban vegetation affects the environment in several ways. It improves air quality, the height of drainage water, and soil properties, balances temperature variations (temperatures are lower in summer and higher in winter in the presence of urban vegetation), reduces UV radiation, reduces noise, increases relative air humidity and contributes to certain types of social development (ecological, aesthetic, economic aspects of urban development). Urban vegetation especially improves microclimatic conditions in large cities and considerably contributes to the urban increase of oxygen. It is of vital interest to pay attention to its size and quantity in urban areas. To assess CO2 absorption and O2 release, the photosynthesis of five tree species and three types of herbaceous plants species was measured. The obtained results show that there is a certain variability in terms of the species that was analyzed. Thus, fast-growing woody deciduous species are more suitable due to the greater and faster growth of biomass, which requires a larger amount of CO2 compared to herbaceous species. The careful calculation indicates the requirement of two to four trees per person or 30-40 m2 of a grassy area per person to balance the inhabitant oxygen consumption. For the overall contribution of green vegetation, the multiple qualitative benefits of green areas in urban areas should certainly be considered.

Continuous increasing leaf photosynthesis may enhance plant yield. As an evolutionary property, plants use less photosynthetic capacity than is theoretically possible. Plant nanobionics is a bioengineering field that improves plant functions using nanoparticles. We applied orange carbon dots (o-CDs) onto the foliage of green beans (Phaseolus vulgaris ) grown in hydroponics to improve their photosynthetic performance and CO2 assimilation. Photosynthesis parameters, photosynthetic pigments content, total phenolic content (TPC) and antioxidative activity (TAA) were measured. Results show that photosynthetic pigments remained unchanged, while photosynthesis was improved. Both o-CDs concentrations decreased TPC and TAA. The light response curve showed higher CO2 assimilation at both o-CDs concentrations, particularly at lower light intensity. Correlation analysis confirmed increased CO2 binding and assimilation at 1mg L-1 . This study demonstrated the potential of using o-CDs as a safe biostimulator through photosynthesis increase and CO2 assimilation without toxic effects on plants. This may stimulate yield increase that paves the way for their agricultural application.

The aim of the present study was to analyze the chemical composition of parsley, parsnip, carrot, and celeriac cultivated at different localities (urban, or suburban/village). The concentrations of heavy metals (cadmium, nickel, chromium) and essential elements (potassium, sodium, calcium, phosphorus) in edible plant parts were determined. Human health risks associated with chronic consumption of potentially contaminated vegetables were assessed through the use of hazard quotients. The concentrations of heavy metals and essential elements in the edible parts of the tested plants varied among plant species, cultivation locality and plant organ (leaf/root). Carrots showed the lowest levels of cadmium, nickel, and chromium accumulation, while the highest concentrations were measured for parsley leaves, with respect to average values. Metal pollution index values obtained for cities were lower than those obtained for some villages and a suburban settlement. The hazard quotient revealed the highest values for cadmium. Positive Pearson's correlation between chromium and nickel was found in many cases. Principal component analysis indicated differences in plants ability to accumulate certain nutrients and pollutants, while sample diversification was closely related to growth site properties. We sincerely hope that the present study will inspire similar investigations in other developing countries, as well as in the Western Balkans region, to obtain broader insight into vegetable food safety and local human health risk. Considering that food quality and safety are major concerns, our results should inform the relevant government authorities and provide a foundation for implementation of a system of controls over cultivation processes and vegetable quality in Serbia., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Rapid industrialization, urbanization, and mine tailings runoff are the main sources of heavy metal contamination of agricultural land, which has become one of the major constraints to crop growth and productivity. Finding appropriate solutions to protect plants and agricultural land from heavy metal pollution/harmful effects is important for sustainable development. Phytoremediation and plant growth-promoting rhizobacteria (PGPR) are promising methods for this purpose, which both heavily rely on an appropriate understanding of the anatomical structure of plants. Specialized anatomical features, such as those of epidermis and endodermis and changes in the root vascular tissue, are often associated with heavy metal tolerance in legumes. This review emphasizes the uptake and transport of heavy metals by legume plants that can be used to enhance soil detoxification by phytoremediation processes. Moreover, the review also focuses on the role of rhizospheric organisms in the facilitation of heavy metal uptake, the various mechanisms of enhancing the availability of heavy metals in the rhizosphere, the genetic diversity, and the microbial genera involved in these processes. The information presented here can be exploited for improving the growth and productivity of legume plants in metal-prone soils.