• 한국약용작물학회지
• /
• 제26권2호
• /
• pp.181-187
• /
• 2018

Background: This study aimed to investigate out the influence of drought stress on the physiological responses of Dendropanax morbifera seedlings. Methods and Results: Drought stress was induced by discontinuing water supply for 30 days. Under drought stress, photosynthetic activity was significantly reduced with decreasing soil water content (SWC), as revealed by the parameters such as Fv/Fm, maximum photosynthetic rate ($P_{N\;max}$), stomatal conductance ($g_s$), stomatal transpiration rate (E), and intercellular $CO_2$ concentration (Ci). However, water use efficiency (WUE) was increased by 2.5 times because of the decrease in $g_s$ to reduce transpiration. Particularly, E and $g_s$ were remarkably decreased when water was withheld for 21 days at 6.2% of SWC. Dendropanax morbifera leaves showed osmotic adjustment of -0.30 MPa at full turgor and -0.13 MPa at zero turgor. In contrast, the maximum bulk modulus of elasticity ($E_{max}$) did not change significantly. Thus, Dendropanax morbifera seedlings could tolerate drought stress via osmotic adjustment. Conclusions: Drought avoidance mechanisms of D. morbifera involve reduction in water loss from plants, through the control of stomatal transpiration, and reduction in cellular osmotic potential. Notably photosynthetic activity was remarkably reduced, to approximately 6% of the SWC.

• 한국초지조사료학회지
• /
• 제20권2호
• /
• pp.77-84
• /
• 2000

Eight-week old perennial ryegrass (Lolium perenne L. cv. Reveille) plants were exposed to different NO3-concentrations or osmotic stress with NaCI. Previously labeled "N was chased during 14 days of non-labeled'NO3 feeding in order to investigate NO3 metabolism in relation to osmoregulation. The short termmeasurement of osmotic potential showed that the extemal concentration of Nos- had not great effect on theosmotic potential, but that osmotic adjustment was observed in NaCl-treated plants. Total uptake of NO 3 - waslargely increased by increasing supply level of NO3 while it was depressed by exposing to osmotic stress.Nitrate reduction increased to more than 29% by increasing extemal NO,- concentration from 1 mM to 10mM. When osmotically stressed with NaCI, nitrate reduction was depressed to about 37% as compared to thecontrol. The decrease in translocation of reduced N into leaves was also observed in NaCl exposed plants. Inthe medium exposed to 10 mM NO,., osmotic contribution of nitrate to cumulative osmotic potential wasdecreased, and it was osmotically compensated with soluble carbohydrate. When osmotically stressed withNaC1, the contribution of chloride was much higher than that of nitrate. The present data indicate that N03-in plant tissues, factually affected by the assimilation of this ion, plays an active role in osmotic regulation incorrelation with other osmotica such carbohydrate and chloride.(Key words : Nitrate metabolism, Osmotic stress, Nitrate supply level, Osmoregulation)ate supply level, Osmoregulation)

• The Korean Journal of Ecology
• /
• 제24권4호
• /
• pp.223-226
• /
• 2001

The leaf water relations and photosynthetic rate during acute soil drying were compared in potgrown grapevine cultivars, Vitis vinifera cv. Chardonnay and V. vinifera cv. Riesling. Leaf water potential in Riesling decreased significantly from day 2 after water had been withheld, while in Chardonnay leaf water potential for the water-stressed plants was almost identical with that in well watered plants during the first 4 days. Higher stomatal conductance and photosynthetic rate in Chardonnay than Riesling were observed until day 3 after withholding water. Photosynthetic rate in water-stressed Chardonnay was not different from that in control plants until day 3 after withholding water, while that in water-stressed Riesling was reduced markedly from day 2. In Riesling, osmotic potential at turgor loss point was not changed irrespective of watering conditions. However, in Chardonnay osmotic potential at turgor loss point decreased more in the water stressed conditions than in well watered conditions. The osmotic adjustment in Chardonnay under water stress conditions must contribute to the maintenance of higher stomatal conductance and photosynthetic rate than those in Riesling for a significant period of the drying process. Though difference in stomatal conductance between the two cultivars was shown in the process of soil drying, stomatal conductance of both cultivars responded to vapor pressure difference between leaf and ambient air, rather than soil water status and leaf water potential.

• Journal of Plant Biology
• /
• 제37권3호
• /
• pp.343-347
• /
• 1994

In order to compare the adjustment of 6 oak species to water stress, the components of water status, tissue elastic modulus, free proline content of leaves and morphological characteristics were determined in pot culture. uercus dentata and . mongolica responded effectively to drought with high root : shoot (R/S) ratio or maintenance of high turgor pressure by large and fast osmotic adjustment and . variabilis with maintenance of high turgor pressure by low elastic modulus under drought. Meanwhile, . aliena and . serrata responded effectively with low omotic potential (Ψo) at full saturation and . acutissima with long root in spite of rigid cell wall and high osmotic potential (Ψo) at full saturation. Proline content in leaves of . dentata, . mongolica and . aliena increased early and rapidly at high leaf water potential (Ψleaf). The results indicate that 6 oak species have adjustment different from each other to water stress.

• 한국환경과학회지
• /
• 제10권1호
• /
• pp.79-84
• /
• 2001

To assess resistance of transgenic tobacco plants which overexpress superoxide dismutase (SOD) and ascorbate peroxidase (APX) in chloroplasts to water stress, changes in leaf water potential, turgor potential, stomatal conductance and transpiration rate were measured. Leaf water potential in all plants remained high up to day 4 after withholding water but thereafter decreased markedly. In spite of a remarkable decrease in leaf water potential, some of transgenic plants maintained higher turgor potential compared with control plant on day 12. In particular, the transgenic plant expressing MnSOD showed an outstanding maintenance in turgor pressure by osmotic adjustment throughout the experiment, resulting in high stomatal conductance and transpiration rate. However, among transgenic plants, osmotic potential was reduced more effectively in multiple transformants such as the double transformant expressing both MnSOD and APX, and the triple transformant expressing CuznSOD, MnSOD and APX than single transformants. Consequently, further research is needed to get general agreement on the tolerance of transgenic plants to water stress at different growth stages for each transgenic plant.

• 한국자원식물학회지
• /
• 제7권1호
• /
• pp.97-101
• /
• 1994

The effects of NaCl salinity on the leaf photosynthesis and water relation of two cultivars of rice(Oryza sativa L.) , the salt-tolerant cultivar Seohae and the salt-senstive cultivar Iri-380 were exam-ined. Two cultivars of rice were grown for 14 days in nutrient solution at SOmM NaCl. Comparing theieaf Na content of two cultlvars, Seohae showed high accumulation of Na content in the leaf blade, while Iri-380 showed low. The Na content in leaf blade reduced the rate of leaf photosynthesis. Salt-tolerant cultivar Seohae was less decreased the rate of leaf photosynthesis than salt- sensitive cultivarIri-380. And Seohae showed larger decreased the osmotic potential in the leaves than Iri-380. This in-dicates that in the salt-tolerant cultivar, osmotic adjustment is developed under saliniEation.

• 한국가시화정보학회지
• /
• 제4권1호
• /
• pp.31-40
• /
• 2006

In this study a newly designed electro-osmotic micro-mixer is proposed. This study is composed of a channel and metal electrodes attached locally on the side wall surface ultimately to control the mixing effect. To obtain the flow patterns, numerical computation was performed by using a commercial code, CFD-ACE. The fluid-flow solutions are the cast into studying the characteristics of stirring in terms of the mixing index. It was shown that the local control of the electric potential can indeed contribute to the enhancement of mixing effect.

• 한국작물학회지
• /
• 제48권6호
• /
• pp.506-515
• /
• 2003

이 논문은 한발저항성이 다른 6개 보리 품종의 한발에 따른 생장, 잎의 수분포텐셜(leaf water potential, LWP), 상대함수량(leaf relative water content, RWC), 삼투압(leaf osmotic potential, OP), 삼투조정(osmotic adjustment, OA), 팽압(leaf turgor pressure, LTP), 순광합섬, 기공전도도, 엽육전도도, 엽록소형광 등의 변화를 조사하여 비교한 결과를 요약하면 다음과 같다. 1 한발 처리시 토양수분포텐셜은 -0.05㎫이었고. 종료시에는 -0.29㎫로 저하하였다. Dicktoo-S 동보리 1호, Dicktoo-L, Dicktoo-T, 수원쌀보리 365호, 탑골보리 품종의 한발처리구 건물중은 각각 대조구(처리기간종 -0.05㎫ 유지)에 비하여 68%, 69%, 70%, 86%, 55%, 37%를 나타내어 Dicktoo 계통과 동보리1호의 한발저항성이 강하였고, 수원쌀보리 365호와 탑골보리는 한발저항성이 약하였다. 2. 한발저항성이 강한 품종은 삼투조정능력이 커서 한발처리에 따른 RWC와 LWP의 저하가 작았고 팽압유지능력이 컸다. 3. 한발처리에 따라 순광합성이 저하하였고 그 저하정도는 한발저항성이 큰 품종이 작았는데, 이는 한발저항성이 큰 품종이 기공전도도, 엽육전도도 및 PSII 최대양자수율(Fv/Fm)의 저하가 적었기 때문이었다. 4. 결론적으로 저항성이 큰 품종은 삼투조정에 의한 수분유지능력이 크고 이에 따라 광합성저하가 적어 상대적으로 생장의 감소가 적은 것으로 판단되었다.

• The Korean Journal of Ecology
• /
• 제28권4호
• /
• pp.231-235
• /
• 2005

상록활엽수의 저온스트레스에 대한 저항성과 내 건성을 파악하고자 대표적인 상록활엽수인 붉가시나무와 구실잣밤나무의 초겨울 비교 수분 관계 특성을 기온 변화와 함께 해석하였다. 10월 이후 강수량과 기온이 급격하게 감소하였으며, 이러한 감소에 대해 붉가시나무와 구실잣밤나무는 세포 내 용질의 양을 증가시켜 삼투 포텐셜을 저하시키는 삼투조절을 행하였다. 그 결과, 두 종 모두 원형질 분리점과 팽윤 상태에서의 삼투 포텐셜은 11월에서 보다 12월에 더욱 낮은 값을 기록하였으며, 이러한 삼투조절 능력은 같은 수분 포텐셜에서도 11월보다 12월에 더욱 높은 팽압을 유지할 수 있게 하였다. 또한, 구실잣밤나무는 이러한 삼투조절 능력에다 붉가시나무에 비해 세포벽 유연성을 높게 가짐으로서 겨울철의 저온 스트레스와 수분 스트레스 하에서 팽압을 유지하는데 기여하고 있는 것을 나타내었다.

• Journal of Ecology and Environment
• /
• 제29권5호
• /
• pp.479-484
• /
• 2006

Ecophysiological parameters of non-transgenic sweetpotato (NT) and transgenic sweetpotato (SSA) plants were compared to evaluate their resistance to multiple environmental stresses. Stomatal conductance and transpiration rate in NT plants decreased markedly from Day 6 after water was withheld, whereas those values in SSA plants showed relatively higher level during this period. Osmotic potential in SSA plants was reduced more negatively as leaf water potential decreased from Day 8 after dehydration treatment, while such reduction was not shown in NT plants under water stressed condition. SSA plants showed less membrane damage than in NT plants. As water stress and high light stress, were synchronously applied to NT and SSA plants maximal photochemical efficiency of PS II ($F_v/F_m$) in NT plants markedly decreased, while that in SSA plants was maintained relatively higher level. This trend of changes in $F_v/F_m$ between SSA plants and NT plants was more conspicuous as simultaneously treated with water stress, high light and high temperature stress. These results indicate that SSA plants are more resistive than NT plants to multiple environmental stresses and the enhanced resistive characteristics in SSA plants are based on osmotic adjustment under water stress condition and tolerance of membrane.