S. Y. Woo

Changes of net photosynthesis, antioxidant enzyme activities, and antioxidant contents of Liriodendron tulipifera under elevated ozone

Liriodendron tulipifera was exposed to gradually elevated ozone concentrations of 100–300 μg kg−1 in the naturally irradiated environment chamber. During 15 d of exposure to O3, net photosynthetic rate (PN) decreased and there was large difference between the control (C) and treatment with ozone (OT), while there was no significant difference in water use efficiency. Total chlorophyll content as well as the value of fluorescence parameter Fv/Fm decreased, while antioxidant enzyme activities related to ascorbate-glutathione cycle increased after 15 d of OT. Unchanged contents of ascorbate and glutathione indirectly suggest that the species hastened the antioxidant’s oxidization/reduction cycle using enzymes instead of expanding their pool against oxidative stress.

Net photosynthetic rate, ascorbate peroxidase and glutathione reductase activities of Erythrina orientalis in polluted and non-polluted areas

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.

Effect of Acacia plantations on net photosynthesis, tree species composition, soil enzyme activities, and microclimate on Mt. Makiling

To determine the effectiveness of rehabilitation on improving ecosystem functions, we examined net photosynthetic rate (PN), tree species composition, soil enzyme activities, and the microclimate (air and soil temperature, relative humidity) of an area on Mt. Makiling that has been rehabilitated and protected from fire for over 12 years. After it was last burned extensively in 1991, restoration was initiated by planting Acacia mangium and Acacia auriculiformis. We selected three areas to study in 2003. Two areas were rehabilitated with A. mangium and A. auriculiformis, and one was still dominated by Imperata cylindrica and Saccharum spontaneum. PN of A. mangium and A. auriculiformis showed significantly lower values than those of I. cylindrica and S. spontaneum. The Acacia plantations had more naturally regenerated tree species than the grassland. Additionally, more tree species appeared in the A. mangium plantation than in the A. auriculiformis plantation. Ficus spetica was present in all of the study sites. Dehydrogenase and phosphatase activities were significantly higher in soil under the Acacia plantations than under grassland. Grassland showed higher air temperature, relative humidity, and soil temperature as well as a larger variation per hour in these parameters compared to the Acacia plantations. The highest air temperature, relative humidity, and soil temperature were measured in April during the dry season. From the regression analysis, soil temperature was significantly correlated with air temperature. Hence plantations, as a rehabilitation activity for grassland, promote natural regeneration and stabilize the microclimate. This stabilization of the microclimate affects establishment and growth of naturally occurring tree species.

Chlorophyll Contents and Growth Performances of the Five Deciduous Hardwood Species Growing Under Different Shade Treatments

We investigated chlorophyll contents and growth performances of five deciduous hardwood species growing in central temperate zone of Korean forest. Cornus controversa, Fraxinus rhynchophylla, Betula schmidtii, Prunus leveilleana, and Acer mono seedlings were grown under four different light intensity regime (full sunlight, , , and, of the full sunlight) for the experiment. The chlorophyll contents of all of the species were highest in of the full sunlight, while lowest under the full sunlight. The relative growth rate of root collar diameter and height were decreased with increasing shading level except for Acer mono that showed the highest relative growth rate under of the full sunlight. Total biomass and root volumes of the seedlings studied decreased as the light intensity decreased with different shade levels. For Acer mono, however, the biomass and root volumes were highest in of the full sunlight. The relative growth rate of root comparing to shoot decreased as shading increased, and as a result, the ratio of aboveground to belowground biomass increased. As the shading level increased, specific leaf area (SLA), leaf area ratio (LAR), and leaf weight ratio (LWR) of most species increased.

Physiological and biochemical responses of two tree species in urban areas to different air pollution levels

We investigated the physiological and biochemical differences in Pterocarpus indicus and Erythrina orientalis grown in four sites at different pollution levels in the Philippines: Makati, Pasig and Quezon (high pollution levels; HP) located in Metro Manila, and La Mesa Watershed (a non-polluted area; NP). Among these four areas, HP sites had higher net photosynthetic rates (PN) than NP sites, except for Makati. Among HP sites, Makati and Quezon had the lowest PN for P. indicus and E. orientalis, respectively. Chlorophyll (Chl) contents were significantly lower in HP than in NP sites. Trees in Makati had the lowest Chl contents among HP sites, and P. indicus had higher Chl contents than did E. orientalis. In addition, the chloroplasts in HP trees had small starch grains with numerous dark, large plastoglobuli. Furthermore, antioxidant enzymes, indicative of the defense mechanism, showed a significantly higher activity in HP than in NP trees.

Recovery of net photosynthetic rate after SO2 fumigation in Quercus acutissima, Pinus densiflora, Populus alba×glandulosa, and Acanthopanax sessiliflorus

After SO2 fumigation, Quercus acutissima and Pinus densiflora maintained high net photosynthetic rate (PN) and did not show visible symptoms of damage. In contrast, Populus alba×glandulosa and Acanthopanax sessiliflorus had significantly reduced PN and showed visible necrosis.

Effects of microenvironment on net photosynthetic rate and growth of four tropical species in the La Mesa watershed

Seedlings of four tree species (Bischofia javanica, Dracontomelon dao, Erythrina orientalis, and Pterocarpus indicus) were planted in flat and sloping grassland in plantation sites established in May 2002 in the La Mesa watershed, Philippines. Tree growth and net photosynthetic rate (PN) were monitored. The height, diameter at the root collar, and PN of the four species grown in the sloping grass site were larger than those of seedlings grown in the flat grass site. In addition, soil moisture contents in the sloping grass site were higher than those of the flat grass site. Growth of the four species was probably strongly associated with microenvironments (e.g. air temperature) in both tested sites.

Physiological changes and growth promotion induced in poplar seedlings by the plant growth-promoting rhizobacteria Bacillus subtilis JS

This study aimed to determine the effects of plant growth-promoting rhizobacteria Bacillus subtilis JS on the growth and physiological changes of Populus euramericana and Populus deltoides × P. nigra. Poplar seedlings were treated with B. subtilis JS and their growth was monitored for up to 120 d. Three different types of treatments [control, B1 (B. subtilis:double-distilled water, 1:100, v/v), and B2 (1:50)] were established. B. subtilis JS enhanced seedling height by 62% and total biomass by 37% after 120 d. Physiologically, the photosynthetic rate increased by 54%, and the total chlorophyll (Chl) content, foliage nitrogen and phosphate content were significantly higher after treatment with B2 than that of the control. These results suggest that the total Chl content is directly related to not only the photosynthetic capacity of the foliage but also to the nitrogen content, indicating that the strain JS may promote the growth of poplar.

Physiological and biochemical responses of roadside trees grown under different urban environmental conditions in Seoul

The present study revealed that Ginkgo biloba and Platanus occidentalis, the most abundant roadside trees in Seoul, grown under polluted environmental conditions, displayed lower contents of total chlorophyll (Chl), carotenoids (Car), and ascorbic acid (AsA) compared to the trees grown under clean conditions. The reduction in Chl, Car, and AsA contents was 59, 53, and 50%, respectively, in G. biloba, contrary to 26, 23, and 24%, respectively, in P. occidentalis. Furthermore, relative ion leakage and leaf temperature was higher in the trees grown under polluted conditions than in those grown under clean conditions. The increase in relative ion leakage and leaf temperature was 58 and 3% for G. biloba and 17 and 4% for P. occidentalis, respectively. Our results, therefore, highlighted the negative impact of urban environmental pollution on the physiological and biochemical parameters in roadside trees.

Stomatal Changes Following Abscisic Acid Treatment in Several Broad-Leaved Trees Undergoing Artificial Shade Treatment

Changes in the resistance of stomatal transpiration following abscisic acid (ABA) treatment were investigated in four species of broad‐leaved trees that underwent artificial shade treatment. In all four species, Betula platyphylla, Betula schmidtii, Zelkova serrata and Acer mono, the light environment exerted a significant influence on the differences of stomatal transpiration and its changes. The time series changes among the four tree species showed varied tendencies according to the type of treatment and level. In the case of Acer mono, Betula platyphylla and Betula schmidtii, transpiration resistance increased following ABA solution treatment at a low concentration of 0.02 mmol. In addition, the differences were increased according to artificial shade treatment levels and with the passage of time. In the case of Zelkova serrata following ABA treatment at a concentration of 0.05 mmol, seedlings which were developed in a high shade treatment with a back‐light rate of 6% showed a high transpiration resistance of 61.36 s-1/cm at 2 hours after treatment, and it increased greatly with increasing shade intensity and treatment concentration. ABA absorption treatment of the branches indicated the strong effect of shade intensity on stomatal diffusive resistance after processing in an artificial light environment. Therefore, we considered that ABA did not affect the physiological characteristics of the tree species but that the damage was caused by the light environment at the time of measurement. We also determined that light was a factor that had some effect on the increase of transpiration resistance through stomatal closure in the case of the seedlings developed in different light environments.