The response of the freshwater microalga Chlorella vulgaris to mercuric ion (Hg2+) stress was examined using chlorophyll a fluorescence image analysis and O-J-I-P analysis as a way to monitor the toxic effects of mercury on water ecosystems. The levels of photosynthetic pigments, such as chlorophyll a and b and carotenoids, decreased with increasing Hg2+ concentration. The maximum photochemical efficiency of photosystem Ⅱ(Fv/Fm) changed remarkably with increasing Hg2+ concentration and treatment time. In particular, above 200 μM Hg2+, considerable mercury toxicity was seen within 2 h. The chlorophyll a fluorescence transient O-J-I-P was also remarkably affected by Hg2+; the fluorescence emission decreased considerably in steps J, I, and P with an increase in Hg2+ concentration when treated for 4 h. Subsequently, the JIP-test parameters (Fm, Fv/Fo, RC/CS, TRo/CS, ETo/CS, ΦPO, ΨO and ΦEO) decreased with increasing Hg2+ concentration, while N, Sm, ABS/RC, DIo/RC and DIo/CS increased. Therefore, a useful biomarker for investigating mercury stress in water ecosystems, and the parameters Fm, ΦPO, ΨO, and RC/CS can be used to monitor the environmental stress in water ecosystems quantitatively.

As cool-season plant, Panax ginseng C. A. Meyer is planted under shade-installation with tall front and low rear. However, at different planting positions, distinct differences come out because ginseng grows at the same position within 3~5 years and the growth circumstance changes a lot by the shade-installation. So, in this study, changes of temperature, photosynthesis and chlorophyll fluorescence with varieties of shading material and planting position were investigated. Light transmittances by polyethylene shade net and silver-coated shading plate as planting materials were measured according to different planting positions. Photosynthetic rate and chlorophyll fluorescence were measured by LI-6400-40 (Li-Cor). According to different planting positions, light intensity was higher in silver-coated shading plate than in polyethylene shade net, and higher at front than rear. Also, photosynthetic rate showed the same tendency, which had a positive correlation to light intensity. But this treatment caused a lower Fo compared with polyethylene shade net because of the stress by light and temperature. Also, Fv/Fm and ETR were higher in silver-coated shading plate. Fo was similar at front and rear according to silver-coated shading plate and ETR was higher at front.

The effects of Cd2+ ions on the Chl a fluorescence of 5 hydrophytes (e.g. Lemna, Salvinia, Ricciocarp, Nymph, Typha plants) were investigated in order to select Cd2+-sensitive plant species and to get informations on physiological responses of plants to Cd2+ stress. Lemna plants were most sensitive to cadmium stress, while Nymph plants were tolerant. However, in all Cd2+-treated plants, Fv/Fm, the maximum photochemical efficiency of PSⅡ, decreased in proportion to the increase of Cd2+ concentration and treatment time. The Chl a fluorescence transient O-J-I-P was also considerably affected by Cd2+ ions; the fluorescence yield decreased considerably in steps J, I and P in Cd2+ treated plants, although it followed a typical polyphasic rise in non-treated plants. In Lemna plants, the functional parameters, ABS/CS, TRo/CS와 ETo/CS and RC/CS, decreased in proportion to the increase of Cd2+ concentration, while N, Mo and Kn increased. The structural parameters, Φpo, Φpo/(1-Φpo), Plabs, SFlabs, Kp and RC/ABS, also decreased according to the increase of Cd2+ concentration. Consequently, Lemna plants will be useful as a experimental model system to investigate responses of plants. And several functional or structural parameters could be applied to determine quantitatively the physiological states of plants under stresses.

This study was conducted to investigate the influence of shading material on the chlorophyll fluorescence, photosynthesis, transpiration, stomatal conductance and its any correlations in Panax ginseng C.A.Meyer. Fo was higher in polyethylene shade net than in silver-coated shading plate, but this treatment caused a lower Fm in comparison with silver-coated shading plate. Also, Fv/Fm and PhiPS2 showed higher in silver-coated shading plate than in polyethylene shade net. The relationship between net photosynthetic rate and transpiration, stomatal conductance were increased as the PAR (Photosynthetic active radiation) was increased and reached maximum at the 200-400 μmol/m2/s of PAR in all of leaves, and the higher in silver-coated shading plate than in polyethylene shade net. A linear equation was obtained between net photosynthetic rate and transpiration, net photosynthetic rate and stomatal conductance. SPAD was higher in silver-coated shading plate than in polyethylene shade net.

The diurnal changes of chlorophyll fluorescence and antioxidative enzyme activity were investigated in the leaves from four subtropical plant species (Crinum asiaticum var. japonicum Bak., Osmanthus insularis Koidz., Asplenium antiquum Makino and Chloranthus glaber Makino) under the natural habitats in summer and winter. The intensity of chlorophyll fluorescence was lower in O-, I-, J-, P-steps of O-J-I-P transient in winter than summer, and prominent diurnal change was not found in the fluorescence intensity of four subtropical plant species in winter. The activity and isoenzyme pattern of SOD and catalase did irregularly change seasonally and diurnally in four subtropical plant species. In contrast, the peroxidase activity and isoenzyme pattern was different depending on plant species and growth seasons; The activity increased slightly more in winter than in summer in four subtropical plant species, and several isoenzymes appeared in the leaves from C. asiaticum var. japonicum, O. insularis and A. antiquum in winter.

This study was conducted to investigate the changes of chlorophyll contents and chlorophyll fluorescence in barley(Hordeum vulgare L.) 7 day old seedling treated with 0.2M, 0.4M, 0.6M, 0.8M, and 1.0M NaCl concentration containing Hepes buffer(pH 7.5). Barley was affected by NaCl treatment. The chlorophyll a, b and carotenoid of barley decreased with an increase in NaCl concentration. However, chlorophyll a, b and carotenoid of barley were not greatly influenced by o.8M and 1.0M NaCl. Fv, Fv/Fm and qP were gradually decreased by higher concentration of NaCl. qP, qNP, qR and qE were gradually decreased by 6hr. During barley chloroplast was development NaCl affected chlorophyll synthesis than photosynthetic activity. Whereas barley seedling leaves were more influenced photosynthetic activity than chlorophyll contents by NaCl.