• Journal of the Korean Institute of Landscape Architecture
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• v.28 no.4
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• pp.21-28
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• 2000

This study is conducted to analyze effects of soil moisture on the growth of maple(Acer palmatum) under indoor low light intensity. Maples grew under three different light intensities such as sunny place(average 353.2W/$m^2$), half shade(average 7.7 W/$m^2$) and shade/(average 1.9W/$m^2$).Under half shady and shady condition, each 24 planters(2 maples planted in each planter) were used and divided into 3 groups treated with different watering points. Three levels of soil water potential were set for watering points, such as -200mbar, -300mbar or -500mbar. Under sunny condition, there were only group of 8 planters, as comparison. Watering was applied when soil water potentials reached -500maber. The results of plant growth experiment are as followed. 1. Under the shady condition, 32 maples died among 48 maples for 7 months. 9 maples survived, watered at soil water potential -200mbar, 5maples at -300mbar and 2maples at -500mbar. 2. Leaf water content ratios were higher under lower light intensity. For the cell wall became thinner under lower light intensity. 3. Maples in shady were easy to die due to having thin cell wall, therefore they were easy to loss the turgor pressure. 4. In case of half shady condition, the group, watered at soil water potential -200mbar, had much smaller amount of rootlet than -300mbar, because there were excessive soil water. The group, watered at soil water potential -500mbar, had smaller amount of rootlet than -300mbar and there was a remarkable difference in leaf water potential in spite of nearly same soil water potential, because leaves received the water stress under lower soil water potential. 5. When maples grew soundly, the leaf water potential was largely influenced by the soil water potential.

• Korean Journal of Plant Resources
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• v.11 no.3
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• pp.307-314
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• 1998

The response of water stree under high and low temperatures, was shown differently according to the longer the suspension period of water supply. Leaf photosynthetic rate(LPS), leaf water potential(WP), relative leaf water content and relative soil water content were lower. At the higher temperatures, the percentate of reduction in LPS and WP was greater than at low temperatures. It is suggested that evaporation rate should be higher in the high temperature than the lower temperature. Also leaf water potential was lower at high temperature than at low temperature. After the 9 th day of treatment , LSP was remarkably reduced at high temperature, but the reduction of LPS was not significant at low temperature. Solidago virga-aurea var. asiatic that maintained LPS of 3rd day after treatment was more strong than other varieties at low temperatures. The silting and curling of leaves were observed symptoms of stress on the 9th day at the both temperatures. The leaves of aster scaber and Ligularia fischeri turned red on the 9th day after treatment at low temperature.

• 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 CROP SCIENCE
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• v.48 no.6
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• pp.506-515
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• 2003

Six barley varieties that showed different degree of drought tolerance were grown with and without drought stress treatment (control), and investigated for the temporal changes in growth and several physiological traits after drought treatment. Soil water potential was -0.05 ㎫ at the initial stage of drought treatment and dropped to -0.29 ㎫ at 19 days after withholding irrigation. Soil water potential (SWP) maintained at -0.05 ㎫ in the control. The dry weight (DW) under the drought treatment were reduced compared to the control as follows: Dicktoo-S (short awn), 69% ; Dicktoo-L (long awn), 70%; Dicktoo-T (tetra), 86%; Dongbori-1, 69%; Suwonssalbori-365, 55% and Tapgolbori, ,37%. Dicktoo lines and Dongbori-1 were more tolerant than Suwonssalbori-365 and Tapgolbori. Leaf relative water contents (RWC) and leaf water potential (LWP) decreased obviously under the drought condition, the decrease being greater especially in the less drought-tolerant barley genotypes. Dongbori-1 and Dicktoo-L in drought treatment showed net photosynthesis of 38% and 17% compared to the control, respectively, and the other four genotypes much lower photosynthesis of 1.1% to 7.0%. Stomatal conductance, mesophyll conductance, and the photochemical efficiency (Fv/Fm) of PS II were reduced by drought treatment, the reduction being greater in drought-sensitive genotypes. The drought-tolerant genotypes had greater osmotic adjustment (OA) capacity under water stress. Thus, the decrease of RWC and LWP was lower and the turgor pressure conservation capacity was higher under water stress in drought-tolerant genotypes. Drought-tolerant genotypes showed less decrease of photosynthesis because stomatal conductance, mesophyll conductance and the ratio (Fv/Fm) of the variable to maximal fluorescence of drought-resistant genotype was decreased less in the drought stress condition. In conclusion, the drought-tolerant genotypes had better water conservation capacity through efficient OA, and this led to the lower decrease of photosynthesis and growth in water stress condition.

• Journal of Korean Society of Forest Science
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• v.63 no.1
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• pp.28-34
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• 1984

This study was to elucidate the relation between the water relations parameters obtained from P-V curves and stomatal closure. The results obtained are as follows: 1) The water potential at incipient plasmolysis obtained from P-V curves was similar to the water potential at critical stomatal closure. 2) The critical stomatal closure of sun leaves appear at -21 bar (-17 bar, shade leaves) in Pinus koraiensis, -20 bar in Pinus rigida, -22 bar in Pinus densiflora, and -24 bar in Larix leptolepis. On a relative water content basis, the critical stomatal closures of sun leaves appear at 85% (82%, shade leaves) in Pinus kordiensis, 77% in Pinus ragida, 85% in Pinus densiflora, and 70% in Larix leptolepis. 3) The incipient stomatal closures of sun leaves appear at -14 bar (-12 bar, shade leaves) in Pinus koraiensis, -10 bar in Pinus rigida, -15 bar in Pinus densiflora, and -6 bar in Larix leptolepis. On a relative water content basis, the incipient stomatal closures of sun leaves appear at 90% in Pinus koraiensis, 93% in Pinus rigida, 90% in Pinus densiflora, and 93% in Larix leptolepis. 4) The leaf conductance was increased by increase in volume-averaged turgor pressure was linearly increased by increase in relative water content.

• Journal of the Korean Society of Tobacco Science
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• v.4 no.2
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• pp.3-10
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• 1982

This experiment was conducted to study the effect of soil water potenial on the growth and internal changes of stressed plants. The experimental imposition of soil water potential ( $\Psi$soil) were -0.1 to -0.2, -0.2 to -0.5, -0.5 to -3.0, -3.0 to -10.0 bar respectively. During water stress all growth rates were depressed, and the most sensitive period to water stress was found to be 10 to 25 days after transplanting. The water potential of leaf was declined rapidly within 12 hours after with holding of water. Nitrate reductase activity was decreased progressively as water deficit was built up in tobacco leaves, but the activity of alpha- amylase and super contents were increased. There were differences in peroxidase isozyme patterns between tile control and water stressed plant. New isozymes started to appear as tobacco leaf water potential decreased.

• Journal of Applied Biological Chemistry
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• v.43 no.3
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• pp.170-175
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• 2000

A pot-lysimeter experiment was conducted with 3-year-old 'Tsugaru' apple (Malus domestica Borkh) trees to examine the changes in oxygen diffusion rate (ODR) with lateral flow velocity of water through soil. The influence of lateral water flow velocity on water relations and elemental content in leaf, and sap temperature distribution patterns of the xylem of trees were also determined. Trees were grown under four soil water regimes: (1) fast laterally flowing (FWT, $2.50{\times}10^{-4}cm\;s^{-1}$), (2) slow laterally flowing (SWT, $0.25{\times}10^{-4}cm\;s^{-1}$), and (3) stagnant water table (WLT) at 60-cm, and (4) drip-irrigation at -40 kPa of soil matric potential as a control. The rate of $O_2$ diffusion converged near $2{\times}10^{-3}g\;m^{-2}\;min^{-1}$ for FWT and control soils, but decreased below $1{\times}10^{-3}g\;m^{-2}\;min^{-1}$ 40 days after treatment (DAT) for WLT soils. For SWT soils, however, the ODR at 15 cm below the soil surface was similar to that of control, but at 45 cm below the soil surface, ODR was similar to that of the WLT treatment. Leaf water potential of FWT and SWT plants was similar to that of control plants, but the values for SWT plants declined by 98 DAT. Leaf water potential of WLT plants decreased from -1.86 MPa (9 DAT) to -2.41 MPa (59 DAT) and finally down to -2.70 MPa. The sap temperature measured at 1100-hr was lowest at top and highest at bottom for FWT and control plants, but this pattern of SWT and WLT plants was disturbed from 29 DAT. However, for SWT plants, such thermal disturbance of sap temperature disappeared from 63 DAT.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.5
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• pp.632-639
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• 1997

The experiment which imposed the water stress to tobacco(Nicotiana tabacum L.) plant was carried at the late of maximum growth period. In order to know the influence of drought stress on the growth and developmemt of tobacco leaves of different position and to elucidate the physiological response of plant to various soil water content, stomatal conductance, and leaf water potential were measured. The drought stress at the maximum growth period negatively affected to the overall growth characteristics of shoot. The response of the growth was small at the middle and the lower leaves, and great at the upper leaves. The relative water content of upper, middle, and lower leaves at the fifth day after treatment were 74, 64, and 59%, respectively, as soil water content was reduced by 4.3%. This suggested that the wilting point of tobacco leaf was about 75%. The leaf water potential was -0.58 MPa in control and dropped to -1.20 MPa at the fifth day after treatment. This indicated that wilting of leaf may occur at the condition in which the difference of water potential between treatment and control, well watered, was greater than about 20%. Stomatal conductance at the fifth day after treatment dropped from 12 mol /$\textrm{m}^2 sec^{-1}$ to 0.8 mol /$\textrm{m}^2 sec^{-1}$ in the middle and the upper leaves. Stomatal conductance of lower leaves already matured were not affected highly by drought stress at the maximum growth period, but maturing leaves, middle and upper leaves, were highly affected by limitation of soil water.

• Magazine of the Korean Society of Agricultural Engineers
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• v.28 no.2
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• pp.31-41
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• 1986

Knowledge of the degree of yield reduction due to water stress at different crop growth stages in rice production is important for rational scheduling of irrigation during periods of insufficient water supply. Previous studies to determine the degree of yield reduction duo to water stress suffered from interruptions by rain during experiment. Also the findings did rot relate the degree of water stress to the soil water potential and water deficit status of rice plants. In this study, two years experiments were conducted using the high yielding rice varieties, an Indica x Japonica (Nampoong) and a Japonica variety(Choochung). These were grown in 1/200$^{\circ}$ plastic pots placed under a rainfall autosensing, sliding clear plastic roof facility to control rainfall interruptions. The results obtained were as follows. 1.The two varieties differed in the growth stage most sensitive to water stress as well as the degree of yield reductions. When rice plants were stressed to the leaf rolling score 4 and soil water potential of about - 20 bar at major crop growth stages which included heading, booting, non-effective tillering, panicle initiation and early tillering stages, the yield reductions in the Indica x Japonica variety were 58%, 34%, 27%, 22%, and 21%, respectively, whereas in the Japonica vairety they were 23%, 36%, 1%, 13% and 22%, respectively. This result show that the recommended drainage during non-effective tillering is valid only for the Japonica variety. Sufficient irrigation at booting, heading and early tillering stages are necessary for both varieties. 2.The two varieties showed visible wilting symptoms when the soil water potential dropped to about - 3.0 bar. The Japonica variety showed more leaf rolling than the Indica X Japonica. However, it had a higher retention of leaf water content and greater stomatal diffusive resistance. When the soil water potential dropped, the Japonica variety showed leaf rolling score (LRS) 1 at 0 soil-5. 0 bar and LRS 2 at 0 soil -6.0 bar while the Indica X Japonica showed LRS 1 at 0 soil - 5.5 bar and LRS 2at 0 Soil - 9.0 bar. The stomatal diffusive resistance was maximum at the second top leaf blade in both varieties at intermediate water stress of 0 soil - 4.5 bar. 3.The number of days that was required for the soil water potential to drop to-3. 0 bar and to - 20.0 bar after drainage of irrigation water from the 20cm deep silty clay loam soil in the pots were 6 and 13 days, respectively for booting stage, and 7 and 11 days, respectively for heading stage, 9 and 12 days, respectively for panicle initiation stage, and 12 and 19 days, respectively for early tillering stage. 4.Water stress during the early tillering stage recorded the longest delay in beading time, the largest reduction in panicle numbers and a substantial yield decrease of 20%. This calls for better water management to ensure the availability of water at this stage, particularly during drought periods. In addition, a reexamination of the conventional inter-drainage practice during the non-effective tillering stage is necessary for the high yielding Indica X Japonica varieties.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.2
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• pp.146-152
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• 1997

Development of shoot and root, leaf water potential and photosynthetic rate affected by water stress in early growing stage of tobacco were surveyed to interpret stress response in terms of plant physiological and agricultural aspects. The growth of shoot and root was highly suppressed by water stress and the difference in dry weight by rewatering was smaller in root than in shoot. The total root length was highly decreased by water stress and the lengths of root for water stress and non-stress were 74m and 84m, respectively, after rewatering. The root growth treated by water stress was increased between 2nd and 3rd day after treatment indicating that temporary water stress at early growing stage might have increased of root zone activity for early growth stage. The leaf water potentials were decreased to -7.63MPa, -9.47MPa, -11.89MPa, -13MPa at the 2nd, 3rd, 4th and 5th day by water stress. The relative water contents were 75%, 62% and 57% at the 3rd, 4th and 5th day after treatment. Photosynthesis was reduced largely by water stress. The photosynthetic rate after treatment at 2nd day and 3rd day was dropped to 18.15$\mu$mol. $CO_2$/$m^2$ㆍsec$^{-1}$ and 9.35$\mu$mol. $CO_2$/$m^2$ㆍsec$^{-1}$. It was never recovered to the normal, even after rewatering. Stomatal conductance had been reduced since 2nd day after treatment and increased after rewatering.