• KOREAN JOURNAL OF CROP SCIENCE
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• v.67 no.2
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• pp.77-84
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• 2022

This study aimed to evaluate the growth, yield, and grain quality characteristics of rice varieties that were subjected to water stress during the tillering stage. We also sought to identify whether water stress could be indicated via the plants' response to chlorophyll fluorescence. In this study, we induced water stress by intentionally cutting off water for 30 days, starting 15 days after transplanting the rice varieties to a greenhouse. We analyzed nine rice varieties, including Ilpum, which is the most frequently cultivated variety in Gyeongsangbuk-do, South Korea. The control group was planted in a paddy field where irrigation was entirely dependent on rainfall. Our results revealed that the heading stage of the nine studied varieties occurred approximately ten days earlier in the rain shelter than in the field. Moreover, the rice yield, head rice rate, and palatability score decreased by 18.6%, 17.1%, and 8.3%, respectively, while protein content increased by 20.2% compared with the control group. The Saenuri and Haimi varieties showed the lowest reduction in yield under the water stress conditions, while the Daebo and Samkwang varieties showed the highest reduction in yield. The chlorophyll fluorescence response after re-irrigation was measured between July 30^th and August 17^th. The ratio of variable fluorescence to maximum chlorophyll fluorescence (F_V/F_M) values failed to recover to their baseline values, resulting in either no change or a reduction in fluorescent response, even after re-irrigation of Daebo and Samkwang varieties. These results can be utilized as empirical data for drought-affected farms to select resistant varieties that can respond to spring drought in the southern plains of Gyeongsangbuk-do.

• Proceedings of the Korean Society of Crop Science Conference
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• 1996.10a
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• pp.78-79
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• 1996

• Proceedings of the Korean Society of Crop Science Conference
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• 2018.10a
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• pp.157-157
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• 2018

• KOREAN JOURNAL OF CROP SCIENCE
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• v.63 no.2
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• pp.164-173
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• 2018

Elevated atmospheric carbon dioxide concentration ($CO_2$) is a major component of climate change, and this increase can be expected to continue into the crop and food security in the future. In this study, Soil-Plant-Atmosphere-Research (SPAR) chambers were used to examine the effect of elevated $CO_2$, temperature, and drought on the canopy architecture and concentration of macronutrients in potatoes (Solanum tuberosum L.). Drought stress treatments were imposed on potato plants 40 days after emergence. Under AT+2.8C700 (30-year average temperature + $2.8^{\circ}C$ at $700{\mu}mol\;mol^{-1}$ of $CO_2$), at maximum leaf area, elevated $CO_2$, and no drought stress, a significant increase was observed in both the aboveground biomass and tuber, and for the developmental stage. Even though $CO_2$ and temperature had increased, AT+2.8C700DS (30-year average temperature + $2.8^{\circ}C$ at $700{\mu}mol\;mol^{-1}$ of $CO_2$ under drought stress) under drought stress showed that the leaf area index (LAI) and dry weight were reduced by drought stress. At maturity, potatoes grown under $CO_2$ enrichment and no drought stress exhibited significantly lower concentrations of N and P in their leaves, and of N, P, and K in tubers under AT+2.8C700. In contrast, elevated $CO_2$ and drought stress tended to increase the tuber Mg concentration under AT+2.8C700DS. Plants grown in AT+2.8C700 had lower protein contents than plants grown under ATC450 (30-year average temperature at $400{\mu}mol\;mol^{-1}$ of $CO_2$). However, plants grown under AT+2.8C700 showed higher tuber bulking than those grown under AT+2.8C700DS. These findings suggest that the increase in $CO_2$ concentrations and drought events in the future are likely to decrease the macronutrients and protein concentrations in potatoes, which are important for the human diet.

• Journal of The Korean Society of Grassland and Forage Science
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• v.17 no.2
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• pp.117-122
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• 1997

This experiment was conducted to evaluate the forage yield and quality and the possibility to provide Festulolium bmunii(Festuca pratensis $Huds{\times}Lolium$ mult~jlotum Lam.) as forage source in Korea. The Festuloliurn braunii were harvested at boot, heading and anthesis stage, respectively. The field trials were performed 6om 1994 to 1996 at the forage experimental field, College of agriculture, Chunpam National University. The results obtained were summarized as follows: 1. The date of boot, heading and anthesis stage of Festulolium bmunii observed in Taejon were May 12, May 23 and June 1 in 1995, and June 1, June 4 and June 9 in 1996, respectively. Winter survival percentage of Festulolium bmunii war ranged 6om 96% to 98% and summer survival percentage were 75-86%. It would suggest that Festulolium brawlii persisted well in the aspect of overwintering, while it wasn' t widely adapted to drought and high temperature in Taejon regions. 2. The CP content and DMD of Festulolium bmunii tended to decline as the growth stage advanced. The CP content and DMD of Festulolium bmunii were high at the boot stage and those at the anthesis stage were low. But fiber contents at the boot stage were lower than those at anthesis stage(P< 0.05). The yields of the DM and DDM with advancing the growing stage tended to increase, while there was no difference in the CPDM yields among stages. On the otherhand, the yields of DM and DDM at the anthesis stage were the highest (P< 0.05), but there was no difference in CPDM yield among stages. Based on the results mentioned above, it is suggested that Festulolium b m n i i has a possibility to use until the anthesis stage under the cutting regimes and that it has a potentiality to provide one of a good forage sources. %'ifqqiZ 43q *(College of Agriculture, Chungnam National Un~versity, Taejon 305-764, Korea)

• Magazine of the Korean Society of Agricultural Engineers
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• v.37 no.5
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• pp.73-80
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• 1995

The uses of stage-storage curve function are diverse in irrigation reservoirs. The curve functions would be used to determine the optimal size of spillway length and the inundation area above full water level based on the flood routing in reservoirs. In addition, the curve function would he used to transform the stage to the storage for the reservoir water management, in which the storage is the supply water. Besides those, the curve is necessary for the planning of dredging, the estimation of the effective and the dead storage, the drought management by reservoir, etc. The curve function data, however, are almost unavailable for these purposes. According to the statistics, about 74% of the 2, 900 resevoirs which are maintained by Farm Land Improvement Association have no more effective data. Therefore, the simulation of the curve function could be better alternative. The curve functions were simulated derivating the regression equations based on the basin relief ratio and the effective depth. The results of the verification show the enough reliability of the application to generate the curve function in some reservoirs which do not have the surveyed stage-storage data. Also, even though the averaged curve function would be applicated without the basin relief ratio data, the result shows that the simulated curve is closer to the real one than the linear function by only the existing effective storage data.

• Journal of Plant Biotechnology
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• v.33 no.2
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• pp.133-137
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• 2006

Evaluation of physiological performance of trehalose-producing transgenic rice line was conducted to investigate drought tolerance at early growth stage. Under artificially induced drought condition of 8% polyethylene glycol 6000, this transgenic rice line had leaf photosynthetic rate of 11.08 uml CO$_2$ $m^{-2}s^{-1}$, leaf transpiration rate of 8.38 mmol $H_2O$ $m^{-2}s^{-1}$ and leaf water potential of -1.12 MPa after 96 hours of treatment. Nakdongbyeo, the parent of this tyansgenic rice line, had photosynthetic rate of 15.42 $\mu$mol CO$_2$ $m^{-2}s^{-1}$, leaf transpiration rate of 8,04 mmol $H_2O$ $m^{-2}s^{-1}$ and leaf water potential of -0.88 MPa. The other variety used in this experiment for comparison, IR 72, showed higher values than both tyansgenic rice line and variety Nakdonbyeo on all three parameters; leaf photosynthetic rate of 20.61 $\mu$mol CO$_2$ $m^{-2}s^{-1}$, leaf transpiration rate of 12.88 mmol $H_2O$ $m^{-2}s^{-1}$, and leaf water potential of -0.82 MPa. So this transgenic rice line did not show superior performance in leaf transpiration rate, leaf photosynthetic rate and leaf water potential compared to variety Nakdongbyeo. This result along with visual observation on leaf rolling and drying during the experimental period indicated poor physiological performance of this transgenic rice line. Further studies on metabolic status of stress-induced trehalose, along with study on physiological response of this transgenic rice line during drought stress would shed more light on overall physiological performance of this transgenic rice line.

• Korean Journal of Environmental Agriculture
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• v.40 no.4
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• pp.290-294
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• 2021

BACKGROUND: Barley sprouts contain a large number of secondary metabolites such as polyphenols, saponarin, and policosanols. The synthesis of such secondary metabolites occurs as a defense mechanism against external environmental stresses. In particular, it has been widely known that drought stress (DS) increases the content of flavonoids in plants. The objective of this study was to investigate the effects of drought stress treatment on the saponarin content in barley sprouts during the growing period. METHODS AND RESULTS: In this study, changes in saponarin content with different DS exposure periods and times were evaluated under the hydroponic system. For establishing different DS treatment periods, water supply was stopped for 1, 2, and 3 days, once leaf length was at 10 cm. To control different DS treatment times, water supply was stopped for 2 days, once leaf lengths were 5, 10, and 15 cm. As a result, the water potential of barley sprouts decreased from -0.8 MPa (before DS treatment) to -1.2, -2.4, and -3.2 MPa (after DS treatment), and reversely recovered to -0.8 MPa after re-irrigation. When 10 cm leaves were subjected to DS for 1 and 2 days, the saponarin content increased by 12 and 10%, respectively, while it increased by 19% when DS was applied to the 5 cm leaves. CONCLUSION(S): The results of this study suggest that drought stress at the early stage of growth (5 cm) is most helpful to increase the saponarin content of barley sprouts.

• Journal of the Korean Institute of Landscape Architecture
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• v.45 no.2
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• pp.51-59
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• 2017

This study evaluated the drought tolerance of Liriope platyphylla F.T.Wang & T.Tang, Dendranthema zawadskii var. lucidum (Nakai) J.H.Park, Hosta longipes (Franch. & Sav.) Matsum., Sedum sarmentosum Bunge and Zoysia japonica Steud. for an extensive green roof. In order to assess drought tolerance of green roof plants, several criteria were measured such as volumetric water content, leaf and soil moisture potential, chlorophyll a and b, chlorophyll fluorescence, photosynthesis, stomatal conductance, transpiration rate and antioxidants. The results of the drought tolerance measurement of green roof plants focused on the gradually withering of plants from lack of volumetric water content. D. zawadskii was the first to show an initial wilting point, followed by Z. japonica, H. longipes and L. platyphylla in order while S. sarmentosum showed no withering. It was concluded that H. longipes, L. platyphylla and S. sarmentosum were highly drought tolerant plants able to survive over three weeks. Furthermore, chlorophyll a and b were divided into two types: Type I, which kept regular content from the beginning to the middle of the period and suddenly declined, like H. longipes and Z. japonica; and Type II, which showed low content at the beginning, sharply increased at the middle stage and decreased, like D. zawadskii, L. platyphylla and S. sarmentosum. Volumetric water content and the amount of evapotranspiration consistently declined in all plant species. The analysis of chlorophyll fluorescence results that S. sarmentosum, which had relatively high drought tolerance, was the last to decline, while Z. japonica and S. sarmentosum withered after rapid reduction. At first, photosynthesis, stomatal conductance and transpiration rate showed high activity, but they lowered as the plant body closed stomata owing to the decrease in volumetric water content. Measuring antioxidants showed that when drought stress increased, the amount of antioxidants grew as well. However, when high moisture stress was maintained, this compound was continuously consumed. Therefore, the variation of antioxidants was considered possible for use as one of the indicators of drought tolerance evaluation.

• Korean Journal of Medicinal Crop Science
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• v.28 no.6
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• pp.412-420
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• 2020

Background: Measurement of chlorophyll fluorescence (CF) is useful for detection the ability of plants to tolerate environmental stresses such as drought, and excessive sunlight. Cnidium officinale Makino is highly sensitive to water stress and excessive sunlight. In this study, we evaluated the effect of soil water and shade treatment on the photosynthesis and leaf temperature change of C. officinale. Methods and Results: C. officinale was cultivated under uniform irrigation for 1 week drought stress (no watering) for 6 days. A significant decrease in CF was observed on the 5th day of withholding water (approximately 6% of soil water content) regardless of shading. Notably, the Rfd_lss parameter (CF decrease rates) with and without shade treatment was reduced by 73.1% and 56.5% respectively, at 6 days compared with those at the initial stage (0 day). The patterns of the degree of CF parameters corresponded to those of the soil water content and difference between leaf temperature (Ts) and air temperature (Ta). Meanwhile, CF parameters recovered to the 3 - 4 days levels after re-watering, while the soil water potential was completely restored. The suitable soil water content for C. officinale optimal growth was between -5 kPa and -10 kPa in this experiment. Conclusions: Lack of soil water in the cultivation of C. officinale, even with shading, decreased latent heat cooling through transpiration. As a result, heat dissipation declined, and the plant was subjected to drought stress. Soil water content plays a major role in photosynthesis and leaf temperature in C. officinale.