• Plant Resources
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• 제3권1호
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• pp.71-78
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• 2000

Autotoxicity restricts reseeding of new alfalfa(Medicago sativa L.) after alfalfa until autotoxic chemical(s) breaks down or is dispersed into external environments, often requiring up to a year or more. One solution for reducing autotoxicity would be to select germplasms or cultivars with tolerance to the autotoxic chemical(5) and use genetically breeding program. Bioassay of seed germination and early seedling growth was conducted to evaluate autotoxic responses of 3 varieties of alfalfa to the water-soluble extracts(at 4 and 8g/L) from alfalfa ‘Cody’leaf by using agar and filter paper medium in a petri-dish assay. Root length at 5 days after seeding was more sensitive to the extract than was hypocotyl length or seed germination, and was a better parameter of autotoxic effects of alfalfa leaf extracts. Use of an agar medium gave better sensitivity of root length than did use of filter paper. Evaluating tolerance with percent of control was more important indicator than was mean of root length because of significant variation among varieties in root length of control treatment. Bioassay ranked varieties in the following order of tolerance on the basis of relative root length; “Cody” >“ Pioneer 5373” >“ Alfagraze”. Seedling growth from old “Cody” seed was more sensitive to the autotoxic chemical(5) than was that from newly produced seed.

• 한국작물학회지
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• 제43권3호
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• pp.161-167
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• 1998

Root and shoot development of two rice (Oryza sativa L.) cultivars with different genetic backgrounds was studied with reference to their relative growth. Tongil type (indica-japonica hybrid) cultivar 'Kuemkangbyeo' and japonica cultivar 'Koshihikari' were grown in $5000^{-1}$ a Wagnar pots under flooded condition. Three plants with roots of both cultivars were taken in every phyllochron through the heading stage to record morphological characteristics of shoot and root system. Compared to Koshihikari, Kuemkangbyeo produced more tillers and had greater shoot weight and leaf area per hill. Length and weight of the root system in both cultivars increased exponentially with time. At the same time, root system development was significantly faster in Kuemkangbyeo than in Koshihikari after the panicle initiation stage. As a result, Kuemkangbyeo has a vigorous root system which consists of larger number of nodal roots compared to Koshihikari. Also, the root length and weight per unit leaf area of Kuemkangbyeo were larger than those of Koshihikari in the later half of growing period, which suggests possible higher physiological activity of the root system of Kuemkangbyeo which is known as a high-yielding cultivar. The relationship between root traits (crown root number, total root length, and root dry weight) and shoot traits (leaf area and leaf+culm dry weight) in both cultivars closely showed allometry until the flag leaf stage.

• The Korean Journal of Ecology
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• 제19권1호
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• pp.36-46
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• 1996

Variation of Al tolerance in Pinus densiflora, P. rigida and P. thunbergii was investigated in a solution culture. Root length decreased as Al concentration increased, and decreased more in dilute culture media than in dense one. Aluminum tolerance based on relative root length was in the order of P. rigida ＞ P. densiflora ＞ P. thunbergii. Al content in tissue increased as Al concentration of the media increased, but the reverse was true for content of Ca and Mg. Al tolerance for root length showed intraspecific variation, even under the same Al concentration in the media.

• 한국연초학회지
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• 제19권1호
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• pp.18-23
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• 1997

The study was carried out to clarify reasonable production of healthy seedling, optimal Pot depth, and appropriate transplanting time, which can be deduced from understanding of seedling quality. Seedling quality results from growth of root and shoot, morphology and distribution of root system under influence of Pot depth during seedling growing period. Stem height, shoot dry weight, leaf area and leaf number were increased in proportion to depth of pots. Growth of shoot and root during seedling growing period showed the most dramatic development between 20th and 25th day after temporary planting. Root number increased as pot depth decrease and total root length and dry weight increased as pot depth increase. In 5cm pot, relative multiplication rate was higher and mean extension rate was lower than other depth of Pot. The limitation of pot volume in which rhizosphere was located enhance the development of roots of second and third order. At 20th days after temporary Planting root distribution was relatively uniform in length and development of adventitious root on stem base was poor as Pot depth decreased.

• Journal of Ginseng Research
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• 제5권2호
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• pp.163-169
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• 1981

In order to clarify the biological effects of chemical mutagen, ethyl methane sulphonate (EMS), in M, seedling(Ponax ginseng C. A. Meyer) . the dehiscent seeds of ginseng were treated with EMS for 12 hours at 20t and Post-washed for 24 to 72 hours. The differences of biological injuries in M, generation due to the concentration of EMS were quite obvious in rate and date of germination, stem length, stem diameter, leaf length, leaf width, root length, root diameter, and root weight . Especially, the seeds treated with the high concentration of EMS , above 0.8%, were not germinated The growth injury was directly proportional to the concentration of EMS but not relative to the post-washing time of afire 25 hours. The useful range of EMS concentration and post-washing time in ginseng seeds were 0.4 % - 0.6% and above 24 hours, respectively.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.231-231
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• 2017

Drought limits rice production under upland condition. This study quantified the effect of rhizobacteria inoculation on rice root system developmental response to drought and its role in maintaining high soil water use, and dry matter production under drought using NSIC Rc192 (rainfed lowland rice variety). The source of inoculant was Streptomyces mutabilis, a recently isolated rhizobacteria containing plant growth promoting compounds such as ACC deaminase, indole-3-acetic acid and phosphatase (Cruz et al., 2014, 2015). In the first experiment, pre-germination inoculation of seeds with S. mutabilis significantly increased the shoot and root (radicle) length as well as root hair lengths, relative to the non-inoculated control. In the second experiment, rice plants inoculated with S. mutabilis and grown in rootbox with soil generally had greater total root length under drought regardless of the timing of inoculations, relative to the non-inoculated control. Consequently, improved root system development contributed to the increase in soil water uptake under drought and thus, dry matter production. Among inoculation treatments, one-time inoculation of S. mutabilis either at pre-germination or pre-drought stress at 14 days after sowing (DAS), had significantly greater shoot dry matter production than three-time inoculation at pre-germination, at thinning (3 DAS) and at pre-drought (14 DAS). This study demonstrated the effectiveness of rhizobacteria (S. mutabilis) containing growth promoting compounds for enhancing drought dehydration avoidance root traits and improving the growth of rice plants under drought condition.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.211-211
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• 2017

This experiments were conducted to investigate seed germination to evaluate the influence of anaerobic digestate on seed germination of perennial ryegrass seeds. The study conducted a germination experiment in petri-dishes, using perennial ryegrass seeds. The treatments were compared: non-treated control treated with distilled water, different concentration of anaerobic digestate. The germination percentage of perennial ryegrass seeds was highest in the fermented anaerobic digestate treatment. Root length of perennial ryegrass seeds was long by 4~5cm in the fermented anaerobic digestate with unfermented anaerobic digestate. In the relative root length ratio was by 30% higher in the in the fermented anaerobic digestate with unfermented anaerobic digestate. The germination index of perennial ryegrass seeds was high by 113% in the fermented anaerobic digestate compared to no treatment. The fermented anaerobic digestate have shown stimulatory effects in germination and development of root. Use of fermented anaerobic digestate can be recommended to farmers as a ecofriendly practice for better germination and growth.

• 대한전기학회논문지
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• 제37권10호
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• pp.694-701
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• 1988

분포형 레일건은 전기자가 이동하는 공안 전기자전류를 거의 일정하게 유지할수 있으며 전류공급영성과 전기자 사이의 거리를 최소로 유지할수 있게 한다. 이 논문은 분포형 레일건에서 전류분포실효저항 및 전류의 실효확산 깊이에 영향을 미치는 인자를 규명한 것이다. 정상상태의 간단한 2차원 모델로 부터 레일의 전류분포와 실효저항을 나타내는 식을 유도하였다. 전류의 확산이 불충분한 조건에서 레일의 실효저항은 레일의 상대속도, 투자솔, 전기자와 전류공급영성과의 거리의 1/2승에 비례하고 도전솔의 1/2승에 반비례하였으며, 전류의 실효확산 깊이는 전기자와 전류공급영성과의 거리의 1/2승에 비례하고 투자솔, 도전솔 및 속도의 1/2승에 반비례하였다.

• 한국작물학회지
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• 제42권2호
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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.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.230-230
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• 2017

About 200 rice varieties for irrigated and rainfed lowland ecosystems were released in the Philippines, which were bred for improving yield under favorable conditions. Root plasticity plays key roles in maintaining crop productivity under abiotic stressed conditions. We hypothesized that some of these varieties possess root plasticity traits in response to water stressed conditions. This study aimed to evaluate the root system development and dry matter production of 14 randomly selected rice varieties (6 irrigated lowland and 9 rainfed varieties) under progressive drought (PDR) and soil moisture fluctuations (SMF) stress conditions. Two experiments were done in rootbox and line source sprinkler systems (LSS). Each of the varieties was subjected to well-watered (WW), PDR and SMF conditions during vegetative stage in rootbox system while the same genotypes were subjected to different intensities of drought stress under LSS. Under rootbox system, PDR and SMF significantly reduced shoot dry matter production in all varieties relative to their WW controls. Among varieties, NSIC Rc238 (irrigated lowland) showed the least reduction in shoot dry weight (SDW) in both PDR (by 11.8%) and SMF (by 26.9%) conditions. Less reductions in SDW of NSICRc238 were partially attributed to the promotion of L-type lateral roots, thus increasing total lateral root length by 24.2% and 30.7% under PDR and SMF, respectively. In LSS, SDW of NSIC Rc238 under mild drought stress (16-21% soil moisture content (SMC) had 31.8% reduction relative to its WW control (${\geq}22%SMC$) and had lower sensitivity drought index. Compared with the IR64 susceptible check and NSIC Rc9 tolerant check, NSIC Rc238 had higher SDW by 90.8% and 38.6%, respectively. Furthermore, no rainfed lowland varieties included in the experiment performed well under different water stress treatments. The results implied that some other irrigated lowland rice varieties may also possess drought dehydration avoidance root plasticity traits under water-stressed growing environments.