• Korean Journal of Breeding Science
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• v.42 no.5
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• pp.540-546
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• 2010

This study was conducted to understand the role of soybean pathogenesis-related 10 (GmPR10) gene in salt tolerance and to develop salt-tolerant rice using GmPR10 cDNA. GmPR10 transgene was expressed constitutively in the shoot and root of the $T_1$ transgenic rice plants. Interestingly, however, the levels of the transgene expression were increased temporally up to over four- to five-fold in the shoot and root by 125 mM NaCl treatment, peaking at six hours after the treatment and decreasing thereafter. Electrolyte leakage of leaf cells under 125 mM NaCl treatment was lower in all the transgenic lines than in the control variety, Dongjin-byeo. Ability of seedlings to recover from 125 mM NaCl treatment for two weeks was higher in the transgenic plants than in the control plants. These results demonstrated that GmPR10 had function to increase cell integrity and promote growth under the saline stress imposed by NaCl. The transgenic line GmPR10-3 which showed highest ability to recover from the saline stress could be used as a potential source for salt tolerance in rice breeding programs.

• Journal of Korean Society of Forest Science
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• v.102 no.4
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• pp.522-529
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• 2013

Climate change will affect the physiological traits and growth of forest trees. This study was conducted to investigate the effects of an experimental warming on growth and physiological characteristics of Pinus densiflora S. et Z. seedlings. One-year-old P. densiflora seedlings were planted in control and warmed plots in April 2010. The air temperature of warmed plots was increased by $3^{\circ}C$ using infrared lamps from November 2010. We measured shoot height, root collar diameter, above and below ground biomass, chlorophyll contents and leaf nitrogen concentration from March 2011 to March 2013. Seedling height and root collar diameter showed no significant difference between warmed and control plots except for root collar diameter measured in June 2012. Seedling leaf biomass was lower in the warmed ($23.94{\pm}2.10g$) than in the control ($26.08{\pm}1.72g$) plots in 2013. Shoot to root ratio (S/R ratio) was lower in the warmed ($1.09{\pm}0.07$) than in the control ($1.31{\pm}0.10$) plots in 2013. Leaf nitrogen concentrations and chlorophyll contents were not significantly different between warmed and control plots except for leaf nitrogen concentration in 2011. Leaf C/N ratio was increased in 2012 under the warming treatment. Low growth and S/R ratio in warmed plots might be related to the higher temperature and water stress. In the future, the below-ground carbon allocation of P. densiflora might be increased by global warming due to temperature and water stress.

• Journal of Bio-Environment Control
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• v.29 no.4
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• pp.388-398
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• 2020

Watermelon yield mainly depends on soil water content controlled by irrigation in a plastic greenhouse. In this study, we investigated the effect of different soil moisture contents affected by irrigation starting point on growth, yield, and physiological responses of small-sized watermelons. Irrigation was initiated at 5 different levels of soil water content as a starting point with soil moisture detecting sensor after 14 days of transplanting, and stopped at 7 ~ 10 days before harvest. These treatments were compared with the conventional periodic irrigation as control. When soil had the lowest moisture content (-50 kPa), the overall shoot growth was retarded, but the root length and root dry weight increased. The photosynthetic parameters (photosynthetic rate, stomatal conductance, and transpiration rate) of watermelon leaves decreased significantly in the lowest soil moisture content (-50 kPa). On the other hand, the photosynthetic rates of watermelon leaves grown with irrigation starting point between -20 and -40 kPa were observed to be higher than those of other treatments. Fruit set rate and marketable fruit yield increased significantly at -30 kPa and -40 kPa. Proline, abscisic acid (ABA), total phenol and citrulline, which are known to contribute to stress tolerance under drought condition, increased as soil water content decreased, particularly, the largest increases were recorded at -50 kPa. From these results, it was found that an appropriate water supply adjusted with an irrigation starting point between -30 and -40 kPa could help to keep favorable soil water content during the cultivation of small-sized watermelons, promoting the marketable fruit production as well as inducing the vigorous plant growth and reproductive development.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.2 no.3
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• pp.10-17
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• 1999

In order to confirm the effectiveness of the natural river improvement technique, the analysis of vegetation was carried out in Yangjae stream between 1996 and 1998. The results of this study showed the numbers of riparian plants had increased from 41 species to 53 species, and the dominant species had changed from annual and biannual(Humulus japonicus, Persicaria thunbergii, Persicaria hydropiper, Panicum dichotomiflorum, Echinochloa crus-galli) to perennials (Phragmites communis). The variation in biomass and biodiversity index were measured and calculated according to the rehabilitation method. Biomass were varied 302 to $828g/m^2$ and biodiversity index was varied 1.53 to 1.52 at point bar plots(A treatment plots) from 1996 to 1998. In conclusion, the natural river improvement technique which has operated in Yanjaecheon for three years has contributed to restoration of riparian plants. Additionally, subsequent study using this technique should be followed in the near future.

• Journal of the Korean Institute of Landscape Architecture
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• v.48 no.5
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• pp.59-66
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• 2020

Recently, cultivation and management technologies have been needed to adapt due to climate change, which is causing abnormal weather conditions. One technique is to increase the utilization of evergreen broad-leaved species with high ornamental value. A total of five treatments were installed (1m×22.5m), including 60g/㎡ and 80g/㎡ using two types mulching material with an overlapping and hole-drilling mulching method and these were compared to un-mulching treatment a total of planted 92㎡ attheWol-aTestSiteForestattheForestforBiomaterialsResearchCenterinJinju-si, Gyeongsangnam-dofor 10monthsusing3-years-oldQuercusglaucaThunb. In comparison with the control site, the 60g/㎡ overlapping method was about 1.9 times higher than the root collar diameter, but there was no statistical significance between the treatments. Healthy seedlings were found to meet these conditions due to high biomass values and below and T/R ratios of 3.0 or lower and H/D ratios of 7.0 or lower. Comparing the values of LWR, SWR, and RWR, which can be evaluated for seedling due to the mulching treatments, as compared to the control, the growth of the ground areas including leaves and stems was enhanced, but the growth of the underground areas containing roots tended to have high control values. Based on this, the SQI value, which can be evaluated for the comprehensive quality of seedlings, was found to be significantly different between the control site and the mulching treatment sites, confirming that the growth and growth improvement effects were achieved with mulching treatments. The chlorophyll content analysis showed that there was a significant difference from the control site, and it was judged that weed generation in the control acted as an environmental stress, causing a decrease in chlorophyll content. It was found that the overlapping 80g/㎡ of polypropylene mulching material generated about 4 times fewer weeds than the control, and the manpower required for the mulching test field and weeding were equal at 3.3 people/100㎡/1 day. Mulching treatments have demonstrated a significant difference in the promotion of growth and quality of the seedlings and are judged as an alternative that can reduce the economic burden incurred by the purchase of the supplies and the manpower required to weed forestry plantations.

• Horticultural Science & Technology
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• v.29 no.6
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• pp.561-567
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• 2011

Cold tolerance of the native Rhododendron species which are on the verge of extinction in Korean nature were compared with the introduced species and its mechanism were studied physiologically with the investigation of the leaf angle, leaf curling, and photosynthetic activity. The degree of cold tolerance measured with the leaf burning after winter season was higher in the native species, Rhododendron brachycarpum and Rhododendron brachycarpum var. roseum than all the introduced species. 'Nova Zembla', an introduced species, showed high sensitivity to the low temperature. Changes in leaf angle by the low temperature were bigger in 2 native species and 'Parker's Pink' than the other introduced species and small comparatively in 'Nova Zembla' and 'Cunningham's White' cultivar. Leaf curling also occurred strongly in 2 native species by the low temperature. While, it was comparatively little and mild in the other introduced species. Therefore these results suggested that the leaf movement such as leaf angle change and curling adapted to the low temperature is positively related to the cold tolerance of 2 native species. By the way, such relationship is not explainable in the cold-sensitive 'Parker's Pink' cultivar showing comparatively stronger leaf movement. Photosynthetic activity measured before the winter season was high in the cold-tolerant R. brachycarpum and its recovery after winter season was faster in the 2 native species and the introduced 'Cynosure' cultivar than the other introduced species. They were the lowest in the most cold-sensitive 'Nova Zembla'. This phenomena occurred similarly even in the stomatal conductivity, suggesting that the movement of water from the roots to the leaves is better and then the leaf burning after winter season become small in the cold-tolerant species. The recovery of photosynthetic activity and stomatal conductivity was comparatively slower in the cold-sensitive 'Parker's Pink'. From the above results, leaf behavior adapted to the low temperature during the winter season and water movement to the leaves are related collectively to the cold tolerance represented as the leaf burning in the Rhododendron species is suggested.

• Journal of Plant Biotechnology
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• v.34 no.1
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• pp.61-68
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• 2007

To develop rice (Oryza sativa L.) cultivars to be planted on salt-affected sites, cell lines with enhanced proline content and resistance to growth inhibition by Azetidine-2-carboxylic acid (AZCA), a proline analogue, were screened out among calli irradiated with gamma ray of 50, 70, 90, and 120 Gy. The calli had been derived from embryo culture of the cultivar Donganbyeo. Selected AZCA resistant lines that had high proline accumulation were used as sources for selection of NaCl resistant lines. To determine an optimum concentration for selection of NaCl resistant lines, Donganbyeo seeds were initially cultured on the media containing various NaCl concentrations (0 to 2.5%) for 40 days, and 1.5% NaCl concentration was determined as the optimum concentration. One hundred sixteen salt-tolerant (ST) lines were selected from bulked 20,000 seeds of the AZCA resistant $M_{3}$ seeds in the medium containing 1.5% NaCl. The putative 33 lines ($M_{4}$ generation) considered with salt-tolerance were further analyzed for salt tolerance, amino acid and ion contents, and expression patterns of the salt tolerance-related genes. Out of the 33 lines, 7 lines were confirmed to have superior salt tolerance. Based on growth comparison of the entries, the selected mutant lines exhibited greater shoot length with average 1.5 times, root length with 1.3 times, root numbers with 1.1 times, and fresh weight with 1.5 times than control. Proline contents were increased maximum 20%, 100% and 20% in the leaf, seed and callus, respectively, of the selected lines. Compared to control, amino acid contents of the mutants were 24 to 29%, 49 to 143%, 32 to 60% higher in the leaf, seed and callus, respectively. The ratio of $Na^{+}/K^{+}$ for most of the ST-lines were lower than that of control, ranging from 1.0 to 3.8 for the leaf and 11.5 to 28.5 for the root, while the control had 3.5 and 32.9 in the leaf and root, respectively. The transcription patterns for the P5CS and NHXI genes observed by RT-PCR analysis indicated that these genes were actively expressed under salt stress. The selected mutants will be useful for the development of rice cultivar resistant to salt stress.

• Journal of Bio-Environment Control
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• v.11 no.4
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• pp.151-156
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• 2002

Root zone cooling, such as soil or nutrient solution cooling, is less expensive than air cooling in the whole greenhouse and is effective in promoting root activity, improving water absorption rate, decreasing plant temperature, and reducing high temperature stress. The heat transfer of a soil cooling system in a plastic greenhouse was analyzed to estimate cooling loads. The thermal conductivity of soil, calculated by measured heat fluxes in the soil, showed the positive correlation with the soil water content. It ranged from 0.83 to 0.96 W.m$^{[-10]}$ .$^{\circ}C$$^{[-10]}$ at 19 to 36％ of soil water contents. As the indoor solar radiation increased, the temperature difference between soil surface and indoor air linearly increased. At 300 to 800 W.m$^{-2}$ of indoor solar radiations, the soil surface temperature rose from 3.5 to 7.$0^{\circ}C$ in bare ground and 1.0 to 2.5$^{\circ}C$ under the canopy. Cooling loads in the root zone soil were estimated with solar radiation, soil water content, and temperature difference between air and soil. At 300 to 600 W.m$^{-2}$ of indoor solar radiations and 20 to 40％ of soil water contents,46 to 59 W.m$^{-2}$ of soil cooling loads are required to maintain the temperature difference of 1$0^{\circ}C$ between indoor air and root zone soil.

• Journal of Plant Biology
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• v.37 no.3
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• pp.387-394
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• 1994

Effects of environmental factors of light, temperature, nitrogen sources and water stress were analyzed quantitatively on the nodule formation and nitrogen fixation activity of autumn olive plant (Elaeagnu$ umbellala Thunb.) during the seedling growth. Seedlings showed the maximum nitrogenase activity of $72.5\;\mu\textrm{M}\;C_2H_4{\cdot}g\;fr\;wt\;nodule^{-1}{\cdot}h^{-1}$ in the early nodulation stage. The relative growth rate and T/R ratio changed from $1.60%{\cdot}d^{-1}$ and 1.12 in the earlier stage to $3.75%{\cdot}d^{-1}$ and 2.31 in the later stage, respectively. light conditions of 20-25, 1015 and 4-6% resulted in decreases of 41, 54 and 71% of the nitrogenase activity, respectively. Nodules incubated in 15, 20, 25 and $30^{\circ}C$ showed the activities of 5.4, 24.7, 51.6 and $58.5\;\mu\textrm{M}\;C_2H_4{\cdot}g\;fr\;wt\;nodule^{-1}{\cdot}h^{-1}$ respectively. Pretreatment with low temperature ($15^{\circ}C$) followed incubation at $30^{\circ}C$ attained higher nitrogenase activity ($66.5\;\mu\textrm{M}\;C_2H_4{\cdot}g\;fr\;wt\;nodule^{-1}{\cdot}h^{-1}$) than that with higher temperature ($35^{\circ}C$). The oxygen pressure above 16 kPa is necessary for saturation of the nodule activity, but the activity was inhibited severely by physical impact such as the exision or isolation of nodules from the root. The relative activities of early nodules grown in pH 5.5, 6.5 and 8.0 were 89, 100 and 40% and those grown in 1 and 3 mM of $NO_3\;and\;NH_4$ were 6, 1 and 68, 50%, respectively. Watering levels of 20, 50 and 100 mL during the seedling growth resulted in 35, 120 and 8 mg of nodule formation and 33.6, 58.4 and $8.4\;\mu\textrm{M}\;C_2H_4{\cdot}g\;fr\;wt\;nodule^{-1}{\cdot}h^{-1}$ of the nitrogenase activity, respectively. Water stress with 86% decrease of soil water content caused temporary wilting point of leaf and a complete disappearance of nitrogenase activity of nodules, though the water content and transpiration rate in plant were reduced to 90 and 53%, respectively.tively.