• Korean Journal of Ecology and Environment
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• v.52 no.2
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• pp.171-177
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• 2019

Smart farm is a breakthrough technology that can maximize crop productivity and economy through efficient utilization of space regardless of external environmental factors. This study was conducted to investigate the optimal growth and physiological conditions of Chinese matrimony vine (Lycium chinense) with LED light sources in a smart farm. The light source was composed of red+blue and red+blue+white mixed light using a LED system. In the red+blue mixed light, red and blue colored LEDs were mixed at ratios of 1:1, 2:1, 5:1, and 10:1, with duty ratios varied to 100%, 99%, and 97%. The experimental results showed that the photosynthetic rate according to the types of light sources did not show statistically significant differences. Meanwhile, the photosynthetic rate according to the mixed ratio of the red and the blue light was highest with the red light and blue LED ratio of 1:1 while the water use efficiency was highest with the red and blue LED ratio of 2:1. The photosynthetic rate according to duty ratio was highest with the duty ratio of 99% under the mixed light condition of red+blue+white whereas the water use efficiency was highest with the duty ratio of 97% under the mixed light of red+blue LED. The results indicate that the light source and light quality for the optimal growth of Lycium chinense in the smart farm using the LED system are the mixed light of red+blue (1:1) and the duty ratio of 97%.

• Journal of Bio-Environment Control
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• v.13 no.4
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• pp.258-265
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• 2004

The experiment was conducted to investigate the effect of EC and pH of nutrient solution on the growth and quality of the single-stemmed rose grown in a rose factory installed with hydroponic system. The growth and quality of the single-stemmed rose were not significantly different from each other with the EC of the nutrient solutions $1.0\~3.5dS{\cdot}m^{-1}$, which resulted in concluding high concentration of the nutrient solution was not necessary. The optimum range of the EC for single-stemmed rose was $1.5\~2.0dS{\cdot}m^{-1}$ considering plant growth, photosynthetic and transpiration rates. The optimum range of the pH for good plant growth without any visible physiological disorder was $4.0\~6.0$. Therefore, to keep the pH of the nutrient solution for rose low compared to other plants was beneficial for plant growth and uptake of the mineral ions.

• Korean Journal of Environmental Agriculture
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• v.20 no.3
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• pp.186-191
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• 2001

Recently, petroleum spray oil(PSO) has been used to control key pests in integrated pest management (IPM) of citrus and other orchards in Australia and USA. In order to clarify the influences of a newly developed PSO (D-C Tron $Plus^{(R)}$) on citrus leaves, 0.33% or 1.0% of PSO were sprayed to potted 4-year-old citrus trees under some kinds of condition, and then the changes of photosynthesis, transpiration, stomatal conductance and chlorophyll fluorescence(Fv/Fm) were determined. When sprayed with 1.0% PSO, the photosynthetic rate, transpiration and stomatal conductance of citrus leaves were decreased by 20%, and then recovered in 20 days after treatment (DAT), while there were little influences by the spray of 0.33% PSO. The value of Fv/Fm decreased more under the $34/24^{\circ}C$ temperature condition than that of under the $30/20^{\circ}C$ and $28/16^{\circ}C$ condition. The high temperature ($50^{\circ}C$ for 10 hours)-treated trees sprayed with PSO 1.0% or PSO 1.0% plus dithianon 1/2000 dilution showed not only the increase of rate in dropped leaf but also the reduced photosynthesis and Fv/Fm compared with $30/20^{\circ}C$ temperature-treated ones. From the results of this study, the spray of 1.0% PSO can inhibit the physiological activities in citrus leaf, particularly under high temperature condition after spray or the mixing-spray with a fungicide (dithianon WP, 75%).

• Journal of The Korean Society of Grassland and Forage Science
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• v.31 no.3
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• pp.269-276
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• 2011

To investigate the physiological effects of mycorrhizal colonization on drought stress tolerance in white clover, the responses of leaf water potential (${\Psi}_{PL}$), relative water content (RWC), leaf dry mass, photosynthesis rate, transpiration, stomatal conductance, proline and ammonia were assessed periodically during 7 days in non-AM and AM plants under wellwatered or drought-stressed conditions. Under well-watered conditions, the examined parameters were not significantly changed or very little affected by AM symbiosis. Drought decreased water potential, relative water content, photosynthesis rate, transpiration and stomatal con ductance by 68.6%, 22.7%, 97.7%, 83.9% and 84.9%, respectively, in non-AM plants, meanwhile 46.8%, 13.4%, 50.3%, 44.8% and 54.7%, respectively, in AM plants. In addition, drought increased ammonia and proline by 31.8% and 162%, respectively, in non-AM plants, while 20.9% and 76.9%, respectively, in AM plants. These results clearly showed that mycorrhizal colonization significantly relieved the responses of physiological parameters to drought stress in white clover.

• Journal of Environmental Science International
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• v.25 no.8
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• pp.1143-1153
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• 2016

Plant biomass, photosystem II (PSII) photochemical activity, photosynthetic function, and zinc (Zn) accumulation were investigated in a sorghum-sudangrass hybrid (Sorghum bicolor ${\times}$ S. sudanense) exposed to various Zn concentrations to determine the elimination capacity of Zn from soils. Plant growth and biomass of the sorghum-sudangrass hybrid decreased with increasing Zn concentration. Symptoms of Zn toxicity, i.e., withering and discoloration of old leaves, were found at Zn concentrations over 800 ppm. PSII photochemical activity, as indicated by the values of $F_v/F_m$ and $F_v/F_o$, decreased significantly three days after exposure to Zn concentrations of 800 ppm or more. Photosynthetic $CO_2$ fixation rate (A) was high between Zn concentrations of 100-200 ppm ($22.5{\mu}mol$ $CO_2{\cdot}m^{-2}{\cdot}s^{-1}$), but it declined as Zn concentration increased. At Zn concentrations of 800 and 1600 ppm, A was 14.1 and $1.8{\mu}mol$ $CO_2{\cdot}m^{-2}{\cdot}s^{-1}$, respectively. The patterns of stomatal conductance ($g_s$), transpiration rate (E), and water use efficiency (WUE) were all similar to that of photosynthetic $CO_2$ fixation rate, except for dark respiration ($R_d$), which showed an opposite pattern. Zn was accumulated in both above- and below-ground parts of plants, but was more in the below-ground parts. Magnesium (Mg) and iron (Fe) concentrations were significantly low in the leaves of plants, and symptoms of Mg or Fe deficiency, such as a decrease in the SPAD value, were found when plants were treated with Zn concentrations above 800 ppm. These results suggest that the sorghum-sudangrass hybrid is able to accumulate Zn to high level in plant body and eliminate it with its rapid growth and high biomass yield.

• Korean Journal of Agricultural and Forest Meteorology
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• v.16 no.4
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• pp.285-296
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• 2014

The impacts of high temperature and drought were studied on the seedlings of three families (superiorgangwon74, intermediate-gangwon77 and inferior-gangwon132) of P. densiflora which had been selected by the based on the growth indexes of 32-year-old. The seedlings were grown in controlled-environment growth chambers with combinations of four temperatures ($-3^{\circ}C$, $0^{\circ}C$, $+3^{\circ}C$ $+6^{\circ}C$; based on the monthly average for 30 years in Korea) and two water conditions (control, drought). The growth performance, photosynthetic parameters and photosynthetic pigment contents were measured at every 30 days under four temperatures and drought condition, and the end of each treatment. The superior family showed higher relative diameter at root collar growth rate and the dry weight than intermediate and inferior family in all treatments. Under elevated temperature and drought condition, growth rate was decreased, and seedlings showed lower growth rate than that of control in three families under low temperature. Photosynthetic rate, stomatal conductance and transpiration rate of three families decreased with the increase of temperature and drought condition, and that of seedlings under low temperature was lower than control. But under elevated temperature and drought condition, water use efficiency increased in three families. Photosynthetic pigment contents of leaves decreased under the increase of temperature and drought condition, but chlorophyll a/b ratio increased with the increase of temperature and drought condition in three families. The superior family showed higher total chlorophyll content than intermediate and inferior family in all treatments. In conclusion, P. densiflora is under changed temperature and drought condition, growth was decreased, seedlings more affected in elevated temperature than that of decreased temperature. The increase in monthly average temperature in Korea of more than $6^{\circ}C$, P. densiflora seedling growth in depending on region may decrease. In this study, the superior family(gangwon74) showed more excellent growth and physiological responses than intermediate (gangwon77) and inferior(gangwon132) family under changes temperature and drought.

• Horticultural Science & Technology
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• v.28 no.6
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• pp.928-936
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• 2010

This study was conducted to select efficient foliage plants for improving indoor environment conditions through the investigation of physiological responses including photosynthetic rate according to temperature, light intensity, and $CO_2$ level. Eight popular foliage plants used in this study were $Hedera$ $helix$ L., $Cissus$ $rhombifolia$ Vahl, $Ficus$ $benjamina$ L. 'Hawaii', $Syngonium$ $podophyllum$ Schott 'Albo-Virens', $Dieffenbachia$ $sp.$ 'Marrianne', $Pachira$ $aquatica$ Aubl., $Spathiphyllum$ $wallisii$ Regel, and $Scindapsus$ $aureus$ Engler. Photosynthetic rate and transpiration rate of the plants subjected to various light intensities (0, 25, 50, 75, 100, 150, 300, and $600{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ PPFD), $CO_2$ levels (0, 50, 100, 200, 400, 700, and $1,000{\mu}molCO_2{\cdot}mol^{-1}$), and two different temperatures (16 and $22^{\circ}C$) were measured. In addition, various parameters in relation to photosynthesis were calculated from the measured data. As a result, the patterns of photosynthesis varied among 8 foliage plants according to light intensity, $CO_2$ level, and temperature. Most foliage plants except $Dieffenbachia$ had high levels of apparent quantum yield, which represents the photosynthetic rate under low light intensity (PPFD $0-100{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$). $Hedera$ $helix$, $Ficus$ $benjamina$, $Pachira$ $aquatica$, and $Spathiphyllum$ $wallisii$ exposed to high light intensity (PPFD $200-600{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$) showed high levels of photosynthesis. $Cissus$ $rhombifolia$ and $Syngonium$ $podophyllum$ were low in $CO_2$ fixation efficiency compared to the other 6 foliage indoor plants. $Hedera$ $helix$ and $Spathiphyllum$ $wallisii$ showed high photosynthetic rate under high $CO_2$ level and vigorous photosynthesis was also observed in $Ficus$ $benjamina$ and $Pachira$ $aquatica$ grown under $22^{\circ}C$. Considering characteristics of indoor environment such as low light, high $CO_2$ level, and low relative humidity, therefore, $Hedera$ $helix$, $Spathiphyllum$ $wallisii$, $Ficus$ $benjamina$, and $Pachira$ $aquatica$ were efficient indoor foliage plants to improve indoor environmental conditions.

• Journal of Korean Society of Forest Science
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• v.83 no.3
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• pp.410-423
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• 1994

Seasonal and diurnal changes of stomatal diffusive resistance(S.D.R.) and transpiration rate(T.R.) were investigated for determining the ecophysiological water relations of economic tree species subjected to chronic water stress or exogenous abscisic acid treatment. Four species of oaks including Quercus serrata, Q. mongolica. Q. acutissima, and Q. variabilis were used as the experimental materials and also Fraxinus rhynchophylla was studied together with oaks. Stomatal diffusive resistances were repeatedly measured on the containerized 1-0 year seedlings subjected to two kinds of soil moisture regime (wet and dry) in June, August, and September by LI-1600 Steady State Porometer of LI-Cor, Inc.. Exogenous abscisic acid (ABA) solutions of 0.5 mM and 0.05 mM in July and August, respectively, were absorbed into shoots cut from the containerized seedlings for determining their effects on stomatal behavior and transpiration. Most of measurements in stomatal diffusive resistance maintained about 5 s/cm in the morning after sunrise despite of different treatments. But the values fluctuated frequently to high level above 20 s/cm through the afternoon until sunset in the seedlings subjected to dry soil moisture regime. Despite of various treatments and environmental conditions, stomatal diffusive resistances of Q. variabilis were more stable than those of Q. serrata or Q. acutissima. Their values of F. rhynchophylla changed more irregularly in comparison with those of oak species. Exogenous abscisic acid absorbed into shoots cut from seedlings increased stomatal diffusive resistance obviously in most of the species studied. The stomatal responses to abscisic acid treatment were more sensitive in July especially in Q. serrata than in Q. variabilis and Q. acutissima. But the effects of ABA treatment were presented more remarkably in Q. acutissima in August. The responses to abscisic acid were not certain in F. rhynchophylla because of their various fluctuation patterns.

• Horticultural Science & Technology
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• v.32 no.6
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• pp.781-787
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• 2014

The effects of elevated temperature and $CO_2$ concentration on vine growth and characteristics of fruits of three-year-old 'Campbell Early' grapevine were investigated. The treatment groups consisted of a control group (ambient temperature and $390{\mu}L{\cdot}L^{-1}\;CO_2$), an elevated temperature group (ambient temperature + $4.0^{\circ}C$ and $390{\mu}L{\cdot}L^{-1}\;CO_2$), an elevated $CO_2$ group (ambient temperature and $700{\mu}L{\cdot}L^{-1}\;CO_2$), and an elevated $CO_2$/temperature group (ambient temperature + $4.0^{\circ}C$ and $700{\mu}L{\cdot}L^{-1}\;CO_2$). The average shoot length was 312.6 cm in the elevated $CO_2$/temperature group, which was higher than the other groups; with 206.2 cm in the control group and 255.6 cm and 224.8 cm in the elevated temperature group and elevated $CO_2$ group respectively. However, the shoot diameter showed a tendency of decreasing in the elevated temperature and elevated $CO_2$/temperature groups. The equatorial diameter of berries was increased in the higher carbon dioxide concentration, and the soluble solid content was the highest in the elevated $CO_2$ group, with $14.6^{\circ}Brix$ among all treatment groups and the lowest in the elevated temperature group ($13.9^{\circ}Brix$). The harvest date was approximately 11 d earlier in the elevated $CO_2$/temperature group and 4 to 2 days earlier in the elevated $CO_2$ group and elevated temperature group, respectively. Regarding the rate of photosynthesis and transpiration during the growth period, higher photosynthetic rates were observed in the elevated $CO_2$ group and the elevated $CO_2$/temperature group during the early stage of growth; however the photosynthetic rate was reduced dramatically in summer, which was contrary to transpiration.

• Journal of Plant Biotechnology
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• v.44 no.4
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• pp.431-437
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• 2017

Mulberry (Morus sp.) of the family Moraceae is very economically important in Asian countries including Korea, because its leaf and fruit have been commercially used in sericulture and horticultural industries. Therefore it is necessary to develop the optimal production system for rapid and cost-effective propagation of mulberry. Our studies focused on establishing an acclimatization method for the successful plantlet production of new cultivar 'Cheongsu' which was transferred ex vitro after in vitro culture. In particular, effect of abscisic acid (ABA) addition into the last subculture medium on plantlet response to subsequent ex vitro transfer and its growth was investigated. During acclimatization, stomatal conductance and transpiration rate of ABA-pretreated plantlets were significantly lower than those of non-treated plantlets. Net photosynthetic rate of ABA-pretreated plantlets decreased after ex vitro transfer but increased after 14 days, and it was mostly higher than that of non-treated plantlets. Moreover, relative water content as well as chlorophyll contents and its ratio were also higher in ABA-pretreated plantlets. On the other hand, proline was considerably higher than in control plantlets. After 1 month of ex vitro transfer, survival rate of ABA-pretreated plantlets was 85.6%, which increased by 29.1% in comparison with control (56.5%). More vigorous growth was also observed in ABA-pretreated plantlets. From these results, it was found that application of ABA to the last subculture medium could improve acclimatization and promote survival of mulberry plantlets after ex vitro transfer, inducing water stress tolerance and alleviating abiotic stresses.