• Horticultural Science & Technology
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• v.34 no.5
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• pp.708-718
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• 2016

Two different pest control programs were applied on 8-year-old 'Ryoka'/M.26 apple trees (Malus domestica Borkh.). Lime sulfur or Bordeaux mixture with emulsified oil were applied 12 times from late March to mid-September as organic treatment, and synthetic chemicals were 7 times applied as control treatment. Over the entire apple-growing season, photosynthesis rates of apple trees were significantly lower in the organic treatment than in the control, and this photosynthetic differences were larger in July and August. Photosynthesis-related parameters such as stomatal conductance and transpiration behaved similarly to photosynthesis. The leaf area in the organic treatment was significantly smaller ($24.7cm^2$) than that in the control treatment ($30.7cm^2$). Organic leaves contained significantly less Chl. a ($15.5mg{\cdot}g^{-1}$) than did control leaves ($17.6mg{\cdot}g^{-1}$). Fruit yield per tree was significantly lower in the organic treatment (18.8 kg) than in the control (24.5 kg), because organic fruits experienced a higher rate of disease infection such as white rot (Botryosphaeria dothidae) and bitter rot (Glomerella cingulata) than did control fruits. Organic fruits had high flesh firmness but less color development (lower Hunter's a values). In this experiment, the pest control program with frequent applications of organic fungicides showed negative effects on photosynthesis and disease infection on leaves and fruits, and thus reduce the fruit quality and yield in 'Ryoka'/M.26 apple trees.

• Plant Biotechnology Reports
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• v.4 no.3
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• pp.213-222
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• 2010

Within their natural habitat, crops are often subjected to drought and heat stress, which suppress crop growth and decrease crop production. Causing overaccumulation of glycinebetaine (GB) has been used to enhance the crop yield under stress. Here, we investigated the response of wheat (Triticum aestivum L.) photosynthesis to drought, heat stress and their combination with a transgenic wheat line (T6) overaccumulating GB and its wild-type (WT) Shi4185. Drought stress (DS) was imposed by controlling irrigation until the relative water content (RWC) of the flag leaves decreased to between 78 and 82%. Heat stress (HS) was applied by exposing wheat plants to $40^{\circ}C$ for 4 h. A combination of drought and heat stress was applied by subjecting the drought-stressed plants to a heat stress as above. The results indicated that all stresses decreased photosynthesis, but the combination of drought and heat stress exacerbated the negative effects on photosynthesis more than exposure to drought or heat stress alone. Drought stress decreased the transpiration rate (Tr), stomatal conductance (Gs) and intercellular $CO_2$ concentration (Ci), while heat stress increased all of these; the deprivation of water was greater under drought stress than heat stress, but heat stress decreased the antioxidant enzyme activity to a greater extent. Overaccumulated GB could alleviate the decrease of photosynthesis caused by all stresses tested. These suggest that GB induces an increase of osmotic adjustments for drought tolerance, while its improvement of the antioxidative defense system including antioxidative enzymes and antioxidants may be more important for heat tolerance.

• ALGAE
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• v.31 no.1
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• pp.49-59
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• 2016

Ulva pertusa, a common bloom-forming green alga, was used as a model system to examine the effects of elevated carbon dioxide (CO₂) and temperature on growth and photosynthetic performance. To do this, U. pertusa was grown under four temperature and CO₂ conditions; ambient CO₂ (400 μatm) and temperature (16℃) (i.e., present), elevated temperature only (19℃) (ET; i.e., warming), elevated CO₂ only (1,000 μatm) (EC; i.e., acidification), and elevated temperature and CO₂ (ET and EC; i.e., greenhouse), and its steady state photosynthetic performance evaluated. Maximum gross photosynthetic rates (GP_max) were highest under EC conditions and lowest under ET conditions. Further, ET conditions resulted in decreased rate of dark respiration (R_d), but growth of U. pertusa was higher under ET conditions than under ambient temperature conditions. In order to evaluate external carbonic anhydrase (eCA) activity, photosynthesis was measured at 70 μmol photons m⁻² s⁻¹ in the presence or absence of the eCA inhibitor acetazolamide (AZ), which inhibited photosynthetic rates in all treatments, indicating eCA activity. However, while AZ reduced U. pertusa photosynthesis in all treatments, this reduction was lower under ambient CO₂ conditions (both present and warming) compared to EC conditions (both acidification and greenhouse). Moreover, Chlorophyll a and glucose contents in U. pertusa tissues declined under ET conditions (both warming and greenhouse) in conjunction with reduced GP_max and R_d. Overall, our results indicate that the interaction of EC and ET would offset each other’s impacts on photosynthesis and biochemical composition as related to carbon balance of U. pertusa.

• Korean Journal of Agricultural and Forest Meteorology
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• v.1 no.1
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• pp.52-59
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• 1999

Vegetation canopy plays an important role in $CO_2$/$H_2$O exchange between the biosphere and the atmosphere by controlling leaf stomata. In this study, rice (Oryza sativa L.), a staple crop in Asia was investigated to formulate its single leaf model of photosynthesis and stomatal conductance. Photosynthesis and stomatal conductance were measured with a portable infrared gas analyzer system. Other plant and meteorological variables were also measured. To evaluate empirical constants in this biochemical leaf model, nonlinear least squares technique was used. The maximum catalytic activity of enzyme and the maximum rate of electron transport were $ 100\mu$㏖ $m^{-2}$ $s^{-1}$ and $140 \mu$㏖ m$^{-2}$ s$^{-1}$ (@ 35$^{\circ}C$), respectively. The empirical constants, m and b, associated with stomatal conductance model were 9.7 and $0.06 m^{-2}$ $s^{-1}$ , respectively. On a leaf scale, agreements between the modeled and the measured values of photosynthesis and stomatal conductance were on average within 20%, and the simulation of diurnal variation was also satisfactory On a canopy scale, the Simple Biosphere model(SiB2) was tested using the derived parameters. The modeled energy fluxes were compared against the micrometeorologically measured fluxes over a rice canopy. Agreements between the modeled and the measured values of net radiation, sensible heat and latent heat fluxes, and $CO_2$ flux (i.e., net canopy photosynthesis) were on average within 25%.

• The Plant Pathology Journal
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• v.35 no.5
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• pp.521-529
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• 2019

Tomato yellow leaf curl China virus is a species of the widespread geminiviruses. The infection of Nicotiana benthamiana by Tomato yellow leaf curl China virus (TYLCCNV) causes a reduction in photosynthetic activity, which is part of the viral symptoms. ${\beta}C1$ is a viral factor encoded by the betasatellite DNA ($DNA{\beta}$) accompanying TYLCCNV. It is a major viral pathogenicity factor of TYLCCNV. To elucidate the effect of ${\beta}C1$ on plants' photosynthesis, we measured the relative chlorophyll (Chl) content and Chl fluorescence in TY-LCCNV-infected and ${\beta}C1$ transgenic N. benthamiana plants. The results showed that Chl content is reduced in TYLCCNV A-infected, TYLCCNV A plus $DNA{\beta}$ (TYLCCNV A + ${\beta}$)-infected and ${\beta}C1$ transgenic plants. Further, changes in Chl fluorescence parameters, such as electron transport rate, $F_v/F_m$, NPQ, and qP, revealed that photosynthetic efficiency is compromised in the aforementioned N. benthamiana plants. The presense of ${\beta}C1$ aggravated the decrease of Chl content and photosynthetic efficiency during viral infection. Additionally, the real-time quantitative PCR analysis of oxygen evolving complex genes in photosystem II, such as PsbO, PsbP, PsbQ, and PsbR, showed a significant reduction of the relative expression of these genes at the late stage of TYLCCNV A + ${\beta}$ infection and at the vegetative stage of ${\beta}C1$ transgenic N. benthamiana plants. In summary, this study revealed the pathogenicity of TYLCCNV in photosynthesis and disclosed the effect of ${\beta}C1$ in exacerbating the damage in photosynthesis efficiency by TYLCCNV infection.

• Journal of Plant Biotechnology
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• v.50
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• pp.127-136
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• 2023

Water scarcity decreases the rate of photosynthesis and, consequently, the yield of banana plants (Musa spp). In this study, transcriptome analysis was performed to identify photosynthesis-related genes in banana plants and determine their expression profiles under water stress conditions. Banana plantlets were in vitro cultured on Murashige and Skoog agar medium with and without 10% polyethylene glycol and marked as BP10 and BK. Chlorophyll contents in the plant shoots were determined spectrophotometrically. Two cDNA libraries generated from BK and BP10 plantlets, respectively, were used as the reference for transcriptome data. Gene ontology (GO) enrichment analysis was performed using the Database for Annotation, Visualization, and Integrated Discovery (DAVID) and visualized using the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway prediction. Morphological observations indicated that water deficiency caused chlorosis and reduced the shoot chlorophyll content of banana plantlets. GO enrichment identified 52 photosynthesis-related genes that were affected by water stress. KEGG visualization revealed the pathways related to the 52 photosynthesisr-elated genes and their allocations in four GO terms. Four, 12, 15, and 21 genes were related to chlorophyll biosynthesis, the Calvin cycle, the photosynthetic electron transfer chain, and the light-harvesting complex, respectively. Differentially expressed gene (DEG) analysis using DESeq revealed that 45 genes were down-regulated, whereas seven genes were up-regulated. Four of the down-regulated genes were responsible for chlorophyll biosynthesis and appeared to cause the decrease in the banana leaf chlorophyll content. Among the annotated DEGs, MaPNDO, MaPSAL, and MaFEDA were selected and validated using quantitative real-time PCR.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.16 no.4
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• pp.335-340
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• 1983

The effects of water temperature, salinity, and silt and clay on the photosynthetic activity of Porphyra yezoensis were measured. The rate of photosynthesis of P. yezoensis increases as the water temperature rises in the range of $8{\sim}16^{\circ}C$ and begin to decrease at $18^{\circ}C$. In the salinity range of $21.5{\sim}33.5\%0$, the rate of photosythesis of P. yezoensis was increased in the sea water of $29.5\%0$ salinity and decreased in $21.5\%0$ salinity. The rates of photosynthesis of P. yezoensis were significantly decreased with increase of the concentration of silt and clay and the time of exposure to suspended silt and clay. Of the combined effects of salinity, and silt and clay on the photosynthetic activity of P. yezoensis, the effects of silt and clay were higher in the low salinity of $21.5\%0$ and $33.5\%0$. The wet weight of P. yezoensis showed a remarkable loss with increase of the concentration of silt and clay and the time of exposure to silt and clay.

• Journal of Korean Society of Forest Science
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• v.63 no.1
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• pp.42-50
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• 1984

Photosynthetic ability and net assimilation rate were compared between two-year-old seedlings of Pinus rigida and of Pinus rigida ${\times}$ P. taeda $F_1$ to examine whether growth potential could be predicted at young stages. Six families per each species used in this study were grown at the nursery of the Institute of Forest Genetics in Suweon. Photosynthesis and net assimilation rate showed seasonal and genetic variations among the families. Photosynthetic ability of most of the families except for three families of Pinus rigida decreased with increasing ages, while net assimilation rate of all the families decreased with increasing ages. The rank of photosynthetic ability and net assimilation rate among the families varied during the experimental period. Thus, growth potential was better predicted from total photosynthetic ability and total net assimilation rate rather titan from photosynthetic ability and net assimilation rate at a certain period. Total photosynthetic ability and total net assimilation rate were correlated with total dry weight. Correlation coefficients were 0.6394 and 0.7998, respectively. Thus, growth potential of the two species could be predicted by the measurement of total photosynthetic ability and total net assimilation rate. Family K.G. No. $13{\times}7-107$ from Pinus rigida ${\times}$ P. taeda $F_1$ and family K.G. No. 1 from Pinus rigida were the best in total photosynthetic ability and total net assimilation rate within species.

• Korean Journal of Medicinal Crop Science
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• v.2 no.1
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• pp.86-94
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• 1994

This study was carried out to get information on the cause of low photosynthesis ofKorean ginseng, a shade plant. Photosynthesis, water content, stomatal conductance and water potential in leaves of ginseng and soybean were investigated. The light intensity for maximum photosynthesis was about $300{\mu}E\;/\;m^2\;/\;s^2$ in ginseng and about $800{\mu}E\;/\;m^2\;/\;s^2$ in soybean, respectively Photosynthesis was remarkably lower in ginseng than in soybean under the same light intensity and $temperature(at\;20^{\circ}C)$. Photosynthesis of detached leaves was stopped in shorter time in ginseng than in soybean particularly at high $temperature(30^{\circ}C)$. The decreasing rate of water content in detached leaves was slower in ginseng than that of soybean, while the remained water level in the leaves was much higher in $ginseng(70{\sim}71%)\;than\;in\;soybean(50{\sim}53%)$ when photosynthesis was stopped. Water content had a positive correlationwith photosynthesis in both plants. However, at the same water level, the ratio of photosynthesis to water content was remarkably lower in ginseng than In soybean. The relationship between the stomatal conductance and photosynthesis was significantly positive correlation in the both plants. The ratio of photosynthesis to stomatal conductance was similar in booth plants below about 40 $mmol\;/\;m^2\;/\;s\;at\;20^{\circ}C$. Water potential was remarkably lower in ginseng than in soybean, and waterpotential had a significantly positive correlation with water content, stomatal conductance and photosynthesis in both plant. These results suggested that the low stomatal conductance and low water potential might cause the low photosynthesis in ginseng compared to soybean.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.60 no.3
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• pp.266-272
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• 2015

High temperature impairs rice grain yield and quality. To understand the effect of high temperature on leaf physiological activity and grain filling, two cultivars of rice that Dongan and Ilpum were exposed to high temperature during ripening stage. Grain filling rate, perfect grain ratio and grain weight of high temperature ($27^{\circ}C{\pm}4^{\circ}C$) treated both rice cultivars were decreased than those of control temperature ($22^{\circ}C{\pm}4^{\circ}C$) treated. The reduction rates of grain filling ratio, perfect grain ratio and grain weight of high temperature treated to control treated rice were higher in Ilpum than Dongan. Chlorophyll contents of rice leaves under high temperature at early ripening stage were higher than those of control temperature, but those were slowly decreased with no difference between temperature treatment since at mid ripening stage. Although chlorophyll a/b ratio under high temperature was decreased from heading to 15 days after heading, that was gradually increased since 15 days after heading. Protein concentrations of rice leaves for ripening stage was a similar pattern with chlorophyll changes. The rate of photosynthesis at 14 days after heading under high temperature was higher than those of control temperature, but there was no difference at those of 7 and 34 days after heading between two temperature treatment. Free sugars under high temperature treated leaves were lower than control temperature. Consequently, these results exhibit that high temperature accelerate leaf physiological activity as chlorophyll synthesis and photosynthesis rate unlike the deterioration of grain filling.