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.

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.

In tropical forests, the shade provided by tree canopies and extreme climate causes inhibition of plant seedling growth due to the lack of light. However, the plants can acclimate to such environmental stress by generating specific responses. The present study aimed to investigate the effects of shading conditions on ecophysiological performance of Narra seedlings (Pterocarpus indicus L.) via a mesocosm experiment. A pot experiment was conducted for 20 weeks in a greenhouse with different shading treatments, 75% (control), 25%, and 4% of full sunlight (FS). As a result, the photosynthetic rate (P_N), Rubisco enzyme activity, maximum carboxylation rate (V_Cmax), and maximum electron transport rate (J_max) in 25% FS treatment were higher or similar to those in control after three weeks of the beginning of shade treatment, whereas the highest values after ten weeks were observed in control. In contrast, the photosynthetic pigments were highest in control after three weeks, while the values were highest in 25% FS treatment after ten weeks. The growth parameters, such as biomass and leaf area, were highest in 75% FS treatment. The expression of Rubisco, phosphoglycerate kinase, glyceraldehyde-3-phosphate dehydrogenase, and fructose-1,6-bisphosphatase were up-regulated in 4% FS treatment compared to control after ten weeks, contributing to tolerating the shade stress. Our findings indicated the capacity of P. indicus seedlings to tolerate and acclimate low light conditions causing shade stress by generating specific physiological and morphological responses, especially Rubisco enzyme activity as well as gene expression related to photosynthetic activity. The present study will improve our understanding of the tolerance mechanism of Narra plant under light-deficient conditions, thereby providing a better strategy for efficiently growing seedlings of this species in tropical rainforests.

Background/Objectives: Globally, antibiotic contamination has become an emerging issue in agricultural lands. The presence of antibiotic residues in farmlands, especially through the application of manure fertilizers containing veterinary antibiotics, e.g., tetracycline (TC), can cause severe toxicity, which inhibits crop growth and performance, subsequently threatening human health via consumption of contaminated products. This study was conducted to evaluate the phytotoxicity of TC on Kimchi cabbage (Brassica campestris L.) during seed germination, seedling, and vegetative growth stages, along with its physiological responses and bioaccumulation under TC stress. Methods: The responses of cabbage plants to TC stress were assessed through a germination test and a pot experiment, conducted for three days and six weeks, respectively, under different doses of TC (0, 5, 10, 25, and 50 mg/L). Results: As a result of the germination test, higher TC doses (25 and 50 mg/L) tended to delay seed germination, but all treatments achieved a 100% germination percentage by Day 3 after sowing. Eight days after sowing, the length of shoots and roots of seedlings exhibited a TC dose-dependent decline, specifically under 50 mg TC/L, showing a considerable decrease of 24% and 77%, respectively, compared to control. Similar results were observed in the plants transitioning from the seedling to vegetative stages in the pot experiment. Four and six weeks after sowing, the 50 mg TC/L dose showed the strongest phytotoxicity in cabbage plants with physiological parameters, such as the maximum photosystem II quantum yield (F_v/F_m), pigment content (chlorophyll and carotenoid), biomass, and leaf number, significantly reduced by 26 to 60% compared to control. Interestingly, at lower TC doses (5 and 10 mg/L), a hormesis effect was observed in the phenotype and biomass of the plants. In addition, the degree of TC accumulation in the plants was highly dose-dependent at Week 4 and Week 6, but a temporal decline in TC accumulation was noted between these time points in all TC treatments. This phenomenon might affect the value of the bio-concentration factor (BCF) as an indicator of the plant’s tendency to uptake TC. That is, in Week 6, the dose-dependent reduction in BCF for TC in the plants was likely attributed to a dilution effect caused by plant biomass increase or a degradation mechanism within the plant. Conclusions: Overall, our findings suggest that tetracycline toxicity induces seed germination delay and influences seedling elongation and photosynthetic functions, ultimately impairing crop growth and performance. Also, the antibiotic dynamics related to accumulation and degradation in plants were identified. These results will not only suggest the toxicity threshold of TC for cabbage but also provide insights into effective soil management strategies for food production safety and agroecosystem sustainability in antibiotic-contaminated soils.

In recent decades, airborne allergens for allergic respiratory diseases have been found to increase significantly by a process of converting coniferous forests into broad-leaved forests in Korea. This study was conducted to evaluate factors, including airborne pollen counts, micromorphology, and flowering phenology, that can affect oak pollen-related allergic symptoms. The catkin of Mongolian oak (Quercus mongolica Fisch. ex Ledeb.) showed the most rapidly blooming catkin on Julian day 104 in flower development. Among six species, the last flowering was observed on Julian day 119 in Korean oak (Quercus dentata Thunb.). The pollen dispersal was persisted for about 32 days from Julian day 104 to Julian day 136. Airborne pollen was observed about 2 weeks after flowering phase H, the senescence phase. Pollen size varied by species, with the largest from Q. mongolica (polar axis length, PL = 31.72 µm, equatorial axis length, EL = 39.05 µm) and the smallest from Jolcham oak (Quercus serrata Murray) (PL = 26.47 µm, EL = 32.32 µm). Regarding pollen wall structure, endexine of Q. dentata was coarsely laminated or fragmented. The endexine thicknesses of Sawtooth oak (Quercus acutissima Carruth.) and Q. serrata were thick and stable, whereas Galcham oak (Quercus aliena Blume), Q. mongolica, and Oriental cork oak (Quercus variabilis Blume) had thinner endexines. The area occupied by pollenkitt of Q. variabilis was significantly larger than that of Q. acutissima. Importantly, Q. variabilis had a distinctly thick 17 kDa protein band, a presumed major allergen. Oak species differ in pollen protein composition, and thus there is a possibility that the allergenic activity of pollen proteins vary depending on oak species. This study highlights the fact that native oak species in Korea differ in flowering pattern of male flowers, pollen morphology, and pollen chemical constituents. These discrepancies in flowering and pollen properties imply variable allergic responses to oak pollen from different species.

Green algae have been receiving widespread attention for their use as biofertilizers for agricultural production, but more studies are required to increase the efficiency of their use. This study aimed to investigate the effects of different levels of Chlorella fusca CHK0059 application on strawberry plant growth and fruit quality. A total of 800 strawberry seedlings were planted in a greenhouse and were grown for seven months under different Chlorella application rates: 0 (control), 0.1, 0.2, and 0.4% of the optimal cell density (OCD; 1.0 × 10⁷ cells mL⁻¹). The Chlorella application was conducted weekly via an irrigation system, and the characteristics of fruit samples were monitored monthly over a period of five months. The growth (e.g., phenotype, dry weight, and nutrition) and physiological (e.g., Fv/Fm and chlorophylls) parameters of strawberry plants appeared to be enhanced by Chlorella application over time, an enhancement which became greater as the application rate increased. Likewise, the hardness and P content of strawberry fruits had a similar trend. Meanwhile, 0.2% OCD treatment induced the highest values of soluble solid content (9.3–12 °Brix) and sucrose content (2.06–2.97 g 100 g⁻¹) in the fruits as well as fruit flavor quality indices (e.g., sugars:acids ratio and sweetness index) during the monitoring, whilst control treatment represented the lowest values. In addition, the highest anthocyanin content in fruits was observed in 0.4% OCD treatment, which induced the lowest incidence of grey mold disease (Botrytis cinerea) on postharvest fruits for 45 days. Moreover, a high correlation between plants’ nutrients and photosynthetic variables and fruits’ sucrose and anthocyanin contents was identified through the results of principal component analysis. Overall, C. fusca CHK0059 application was found to promote the overall growth and performance of strawberry plants, contributing to the improvement of strawberry quality and yield, especially in 0.2% OCD treatment.