We evaluated surface-based analysis for assessing the possible relationship between the microstructural properties and particulate matter (i.e., two size fractions of PM_2.5 and PM₁₀) adsorption efficiencies of their leaf surfaces on ten woody species. We focused on the effect of PM adsorption capacity between micro-morphological features on leaf surfaces using a scanning electron microscope and a non-contact surface profiler as an example. The species with higher adsorption of PM₁₀ on leaf surfaces were Korean boxwood (Buxus koreana Nakai ex Chung & al.) and evergreen spindle (Euonymus japonicus Thunb.), followed by yulan magnolia (Magnolia denudata Desr.), Japanese yew (Taxus cuspidata Siebold & Zucc.), Japanese horse chestnut (Aesculus turbinata Blume), retusa fringetree (Chionanthus retusus Lindl. & Paxton), maidenhair tree (Ginkgo biloba L.), and royal azalea (Rhododendron schlippenbachii Maxim.). There was a higher capacity for the adsorption of PM_2.5 on the leaf surfaces of B. koreana and T. cuspidata, followed by A. turbinata, C. retusus, E. japonicus, G. biloba, and M. denudata. In wax layer tests, T. cuspidata, A. turbinata, R. schlippenbachii, and C. retusus showed a statistically higher PM_2.5 capturing capacity than the other species. Different types of trichomes were distributed on the adaxial and abaxial leaves of A. turbinata, C. retusus, M. denudata, pagoda tree (Styphnolobium japonicum (L.) Schott), B. koreana, and R. schlippenbachii; however, these trichomes were absent on both sides of the leaves of G. biloba, tuliptree (Liriodendron tulipifera L.), E. japonicus, and T. cuspidata. Importantly, leaf surfaces of G. biloba and S. japonicum with dense or thick epicuticular leaf waxes and deeper roughness revealed lower PM adsorption. Based on the overall performance of airborne PM capture efficiency, evergreen species such as B. koreana, T. cuspidata, and E. japonicus showed the best results, whereas S. japonicum and L. tulipifera had the lowest capture. In particular, evergreen shrub species showed higher PM_2.5 depositions inside the inner wall of stomata or the periphery of guard cells. Therefore, in leaf microstructural factors, stomatal size may be related to notably high PM_2.5 holding capacities on leaf surfaces, but stomatal density, trichome density, and roughness had a limited effect on PM adsorption. Finally, our findings indicate that surface-based microstructures are necessarily not a correlation for corresponding estimates with leaf PM adsorption.

Natural regeneration is an essential component of forest dynamics and the recovery of ecosystem functions. Therefore, understanding regeneration status, and how abiotic and biotic factors affect it, is important for ecological studies. This study discovered different regeneration statuses of tropical forests in response to differences in rainfall in Myanmar, and the environmental and overstory factors that had the most influence on understory regeneration. Study sites were set up in regions with 625 to 2035 mm of annual rainfall, and ecological characteristics were measured. According to the results, natural regeneration increased with rainfall, showing a good regeneration status at all sites. Forests within a range of 1411–2035 mm of annual rainfall had a significantly higher density and species diversity at specific natural regeneration stages than those with 625–1029 mm. Not only abiotic but also overstory structure affected the natural regeneration of forests. However, not all factors influenced natural regeneration status. Overstory size distribution parameters did not show a significant influence on natural regeneration. Average annual rainfall (abiotic), as well as ecosystem complexity, density, species richness, and diversity (overstory), were found to be the most influential factors for the density and diversity of natural regeneration. The results of this study will support silviculture and the management of tropical forests.

Global warming and ozone (O₃) pose serious threats to crop yield and ecosystem health. Although neither of these factors will act individually in reality, most studies have focused on the responses of plants to air pollution or climate change. Interactive effects of these remain poorly studied. Therefore, this study was conducted to assess the effects of optimal (22/20 °C day/night) and elevated temperature (27/25 °C) and/or ambient (10 ± 10 nL L⁻¹) and elevated O₃ concentrations (100 ± 10 nL L⁻¹) on the growth, physiology, and reactive oxygen species (ROS) accumulation of leaf mustard (Brassica juncea L.). The aim was to examine whether elevated temperature increase the O₃ damage due to increasing stomatal conductance, and thus, O₃ flux into the leaf. Significant reductions in photosynthetic rates occurred under O (elevated O₃ with optimal temperatures) and OT (elevated O₃ and temperature) conditions compared to C (controls). Stomatal conductance was significantly higher under T than in the C at 7 DAE. Under OT conditions, O₃ flux significantly increased compared to that in O conditions at 7 days after exposure (DAE). Significant reductions in total fresh and dry weight were observed under OT conditions compared to those under O. Furthermore, significant reductions in levels of carotenoids and ascorbic acid were observed under OT conditions compared to O. Lipid peroxidation and accumulation of ROS such as hydroxyl radical, hydrogen peroxide, and superoxide radical were higher under O and OT conditions than in C conditions at 7 and 14 DAE. As a result of O₃ stress, the results of the present study indicated that the plant injury index significantly increased under OT compared to O conditions. This result suggested that elevated temperature (+5 °C) may enhance O₃ damage to B. juncea by increasing stomatal conductance and O₃ flux into leaves.

We investigated net photosynthetic rate and antioxidative enzyme activities in Erythrina orientalis grown in three different sites: Makati and Quezon (cities with high levels of air pollution, HP) and La Mesa (a non-polluted area, NP). Photosynthetic activity of E. orientalis was significantly reduced in the HP cities. In contrast, activities of the antioxidative enzymes ascorbate peroxidase and glutathione reductase were significantly higher in HP cities than in the NP area.

Plants can undergo external fluctuations in the natural light and dark cycle. The photosynthetic apparatus needs to operate in an appropriate manner to fluctuating environmental factors, especially in light. Yellow-poplar seedlings were exposed to nighttime artificial high-pressure sodium (HPS) lighting to evaluate night light-adaptation strategies for photosynthetic apparatus fitness relative to pigment contents, photosystem II photochemistry, photosynthetic parameters, histochemical analysis of reactive oxygen species, and plant biomass. As a result, seedlings exhibited dynamic changes including the enhancement of accessory pigments, the reduction of photosystem II photochemistry, increased stomatal limitation, downregulation of photosynthesis, and the decreased aboveground and belowground biomass under artificial night lighting. Histochemical analysis with 3,3′-diaminobenzidine (DAB) and nitroblue tetrazolium (NBT) staining indicates the accumulation of in situ superoxide radicals (O₂⁻) and hydrogen peroxide (H₂O₂) in leaves exposed to the lowest level of artificial night lighting compared to control. Moreover, these leaves exposed to artificial night lighting had a lower nighttime respiration rate. These results indicated that HPS lighting during the night may act as a major factor as repressors of the fitness of photosynthesis and growth patterns, via a modification of the photosynthetic light harvesting apparatus.