• KOREAN JOURNAL OF CROP SCIENCE
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• v.64 no.3
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• pp.213-224
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• 2019

There is an increasing frequency in the occurrence of abnormal weather phenomena such as sharp increases and decreases in temperature. Under these weather conditions, the heading time of rice changes unexpectedly, which poses problems in agriculture. Therefore, we investigated the effect of temperature on the heading response at different growth stages in rice. During the period from transplanting to heading, the plants were subjected to different temperature treatments, each for a 9-day period, to observe the heading response. For the heading date analysis, "heading date" was defined as the number of days from transplanting to the appearance of the first spikelet. We found that the influence of temperature increased in the order of rooting stage, followed by meiosis, early tillering, spikelet differentiation, and panicle initiation stage in all ecological types and cultivars. In particular, unlike the results reported previously, the effect of temperature on heading during the photo-sensitive period was very small. Meanwhile, the influence of temperature on vegetative growth response at different growth stages was not consistent with heading response. These results can be used as basic data for predicting the variation in heading date owing to temperature variation at each growth stage. In addition, we propose that the concept of day length should be included in determining the influence of temperature on the photo-sensitive period.

• FLOWER RESEARCH JOURNAL
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• v.18 no.4
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• pp.238-243
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• 2010

This study was conducted to investigate effects of nutrient solution pH control agent and foliar spray of ethephon on the reduction of stem inside-cavity and improvement of flower quality in chrysanthemum 'Baekma'. Changes of pH in nutrient solution as affected by the kind of pH control agent showed more settled pattern in the plot of KOH treatment than in others. Plant growth and development such as cut flower length, leaf numbers, cut flower weight and petal number were the greatest in the plot of KOH. However, the size and area of stem cavity was large in KOH rather than $KHCO_3$. As changes in the absorbing patterns of mineral elements as affected by nutrient solution pH control agent in closed system, contents of total nitrate, phosphorus, potassium and calcium by $KHCO_3$ was absorbed into the plant less than KOH, so that it remained a lot of mineral element residues rather than KOH in closed system. Plant growth as affected by the foliar spray of ethephon showed growth retardation effect in the plot of solution diluted to 1 : 500 and growth promotion effect in the plot of solution diluted to 1 : 1,000 or 1 : 2,000. The number of petals was the best in the plot of foliar spray of ethephon solution diluted to 1 : 1,000 before flowering at 45 days showing 331 petals compared to control showing 302 petals. The size and area of stem cavity as affected the foliar spray of ethephon was smaller 1 mm and 7%, respectively, in the plot of solution diluted to 1 : 2,000 before flowering at 30 days than in control. Therefore, treating pH stabilization using KOH after floral initiation stage with the foliar spray of ethephon solution diluted to 1 : 2,000 before flowering at 30 days would help to reduce stem cavity size and improve flower quality in hydroponically grown chrysanthemum 'Baekma'.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.46 no.3
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• pp.195-201
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• 2001

Sowing date experiments were carried out by employing a rice variety "Kwanganbyeo" in both field and phytotron with natural daylength. In phytotron, temperatures were controlled at daily mean of 21$^{\circ}C$ and 24$^{\circ}C$. The responses of final leaf number and beading date were analyzed in relation to daylength during photo-sensitive period (PSP). Based on the component models predicting the final leaf number and leaf appearance rate, a rice phenology model was established and verified. Days from sowing to flowering (DSF) were shortened and final number of leaves (FNL) increased as sowing dates were delayed from 25 April to 5 June in field and phytotron. The increased leaf appearance rate (LAR) and the reduced FNL, respectively, due to the higher temperature and the shorter daylength in delayed sowings in the field brought about greater shortening of DSF than in the phytotron where only FNL was reduced by shorter daylength in delayed sewings. FNL showed very close relationship with the average daylength during PSP of six-leaf stage to panicle initiation, being well fitted to the following rational function ($R^2$=0.98):(equation omitted) where D is daylength and a, b, and c are the constants that were estimated as 14.694, -0.992, and -0.068 in Kwanganbyeo, respectively. The rice phonology model, which was composed of two component models for LAR and FNL, predicted DSF very accurately. The differences between the observed and predicted DSF was less than two days in the sewing date field experiments in 1999 and 2000 of which data were not used for the model construction.struction.

• Korean Journal of Weed Science
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• v.6 no.1
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• pp.1-6
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• 1986

The growth, development, and morphological characteristics of Echinochtoa colons (L.) Link were determined through one life cycle. E. colons emerged 2 to 3 days after seeding (DAS) and reached the two leaf stage by 8 DAS. During the early growth stages, root length was greater than plant height, but the relationship was reversed from 4 weeks after seeding (WAS). Tillering started from the third leaf of the main culm as the sixth leaf on the main calm emerged. The unfolding of the leaves and tillering followed a regular pattern during the vegetative growth period. This resulted in the production of 19 tillers (5 primary, 12 secondary, 1 tertiary, and I nodal) at the 14-leaf stage. Shoot-root weight ratio was highest just before panicle initiation. The second spike from the top of the panicle was the shortest and produced the fewest seeds. Thereafter, spike length and the number of seeds per spike generally increased, the lower the position of the spike on the panicle. Seeds on the lower spikes weighed less and had lower germination ability than those from the upper spikes. Adventitious roots arose from the leaf sheath bases of a flowering stalk. The ability to produce adventitious roots was greater in a younger stalls than in an older stalk.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.77-77
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• 2017

The sensitivities to photoperiod and temperature give guidance to choose an adaptable genotype for specific area in soybean production. However, there is insufficient information about the variation of sensitivities to photoperiod and temperature with wide genetic background. We investigated the sensitivities to photoperiod and temperature using 82 soybean mini core collection lines provided by NIAS gene bank of Japan. The seeds were sown on 28 May and 4 August in 2015, 24 May and 5 August in 2016 at field in Saga, Japan ($33^{\circ}$ 14' 32'' N, $130^{\circ}$ 17' 28'' E) for the early (average photoperiod and temperature: 15.2 h and $25.1^{\circ}C$) and late (13.6 h and $27.2^{\circ}C$) sowing respectively. The plants were also grown in the growth chamber under 12 h photoperiod with three temperature regimes (day/night temperature: $25/18^{\circ}C$, $28/22^{\circ}C$ and $33/28^{\circ}C$). Emergence date, days to first flower were recorded with 10 plants in the field and 2 plants in the growth chamber for each line. The data for daily average temperatures and photoperiodic hours were collected from weather station. The days from emergence to first flower open (DEF) were varied from 23-92 (2015 and 2016) in early sowing whereas 18-68 (2015) and 18-59 (2016) in late sowing. The shortened DEF in late sowing could be caused by both short photoperiod and high temperature in late sowing. However, the accumulated temperatures during emergence to first flower open (ATEF) were less variable in comparison with DEF, suggesting the ATEF is dependent mostly on the photoperiod. The ATEF were found same between early and late sowing in some early flowering lines (e.g. $686.7^{\circ}C$ and $687.6^{\circ}C$ in HEUKDAELIPS, $728.8^{\circ}C$ and $706.3^{\circ}C$ in WILLIAMS'82) which indicated that these would be insensitive to day length. In the growth chamber experiment, the variation in both DEF and ATEF was a little greater at low temperature ($25/18^{\circ}C$) but almost same at middle ($28/22^{\circ}C$) and high ($33/28^{\circ}C$) temperatures. Since the less differences in ATEF were found between the three temperatures, it is suggested that the temperature plays only a quantitative effect on the flower initiation, and the large ATEF in some lines may indicate the stronger photosensitivity even at 12 h or longer juvenile phase. Some lines with the lowest ATEF regardless of growth conditions, such as FISKEBY V, KE 32 (ATEF: 559.6-666.5, 587.7-709.5) might lack the sensitivities to both photoperiod and temperature. The results suggested that soybean genotypes has wider variation in sensitivity to photoperiod, whereas less variation to temperature.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.57 no.2
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• pp.106-112
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• 2012

In order to understand the growth and ecophy -siological response of ginseng to global warming condition, we cultivated one and two year ginseng seedlings in control (ambient $CO_2$ + ambient temperature) and global warming treatment (elevated $CO_2$ + elevated temperature) from March 2010 to July 2011. Shoot appearance and initiation of flowering were advanced by 3-4 days in global warming treatment than in control. However, timing of fruit setting and seed ripeness was similar in both control and global warming treatment. Shoot length was longer in global warming treatment than in control, and also the number of leaves was much in global warming treatment. Fresh root weight was not different between control and global warming treatment. Photosynthetic rate was higher in global warming treatment than at control. Photosynthetic rate and transpiration rate were higher in two year seedlings than in one year seedlings at control, but was not different between seedling age of ginseng in global warming treatment. Water use efficiency was higher in one year seedlings than two year seedlings at control and global warming treatment. These results demonstrated that Korean ginseng more or less positively responds to global warming situation.

• Korean Journal of Environment and Ecology
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• v.28 no.6
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• pp.634-641
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• 2014

In order to elucidate the ecological and phenological responses of bean under global warming situation, we investigated leafing and flowering phenomena and growth traits of Baktae and Seomoktae in control plot (ambient $CO_2$ concentration and temperature) and warmed plot (elevated $CO_2$ concentration and increased temperature than control) in green house. Average $CO_2$ concentration and temperature were set 540 ppm in treatment and higher $2.2^{\circ}C$ in treatment than control. The appearance of leaf unfolding and the initiation of blooming and fruit maturing in Seomoktae were late in treatment than control. In case of Baktae, the number of total pods and seeds per plant in treatment was fewer than that in control. For Seomoktae, the number of total pods per plant and weight of total seeds per plant were decreased in treatment than in control. Thus, the number of pods and seeds of Baktae declined and the production of Seomoktae was decreased under global warming condition. This result indicates that site selection and crop yield for cultivating of the bean may be changed into new area due to global warming condition.

• Korean Journal of Remote Sensing
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• v.23 no.2
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• pp.145-152
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• 2007

The polarimetric backscattering coefficients of a wet-land rice field which is an experimental plot belong to National Institute of Agricultural Science and Technology in Suwon are measured using ground-based polarimetric scatterometers at 1.8 and 5.3 GHz throughout a growth year from transplanting period to harvest period (May to October in 2006). The polarimetric scatterometers consist of a vector network analyzer with time-gating function and polarimetric antenna set, and are well calibrated to get VV-, HV-, VH-, HH-polarized backscattering coefficients from the measurements, based on single target calibration technique using a trihedral corner reflector. The polarimetric backscattering coefficients are measured at $30^{\circ},\;40^{\circ},\;50^{\circ}\;and\;60^{\circ}$ with 30 independent samples for each incidence angle at each frequency. In the measurement periods the ground truth data including fresh and dry biomass, plant height, stem density, leaf area, specific leaf area, and moisture contents are also collected for each measurement. The temporal variations of the measured backscattering coefficients as well as the measured plant height, LAI (leaf area index) and biomass are analyzed. Then, the measured polarimetric backscattering coefficients are compared with the rice growth parameters. The measured plant height increases monotonically while the measured LAI increases only till the ripening period and decreases after the ripening period. The measured backscattering coefficientsare fitted with polynomial expressions as functions of growth age, plant LAI and plant height for each polarization, frequency, and incidence angle. As the incidence angle is bigger, correlations of L band signature to the rice growth was higher than that of C band signatures. It is found that the HH-polarized backscattering coefficients are more sensitive than the VV-polarized backscattering coefficients to growth age and other input parameters. It is necessary to divide the data according to the growth period which shows the qualitative changes of growth such as panicale initiation, flowering or heading to derive functions to estimate rice growth.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.26 no.1
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• pp.69-89
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• 1981

Stevia (Stevia rebaudiana Bertoni) is a perennial herb widely distributed in the mountainous area of Paraguay. It belongs to the family Compositae and contains 6 to 12 percent stevioside in the leaves. Stevioside is a glucoside having similar sweetening character to surgar and the degree of sweetness is approximately 300 times of sugar. Since Korea does not produce any sugar crops, and the synthetic sweetenings are potentially hazardous for health, it is rather urgent to develop an economical new sweetener. Consequently, the current experiments are conducted to establish cultural practices of stevia, a new sweetening herbs, introduced into Korea in 1973 and the results are summarized as followings: 1. Days from transplanting of cuttings to the flower bud formation of 6 stevia lines were similar among daylengths of 8, 10 and 12 hours, but it was much greater at daylengths of 14 or 24 hour and varietal differences were noticable. All lines were photosensitive, but a line, 77013, was the most sensitive and 77067 and Suweon 2 were less sensitive to daylength. 2. Critical daylength of all lines seemed to be approximately 12 hours. Growth of plants was severely retarded at daylengths less than 12 hours. 3. Cutting were responded to short daylength before rooting. Number of days from transplanting to flower bud formation of 40-day old cuttings in the nursery bed was 20 days and it was delayed as duration of nursery were shorter. 4. Number of days from emergence to flower bud formation was shortest at short day treatment from 20 days after emergence. It was became longer as initiation of short day treatment was earlier or later than 20 days. 5. Plant height, number of branches, and top dry weight of stevia were reduced as cutting date was delayed from March 20 to May 20. The highest yield of dry leaf was obtained at nursery duration of 40-50 days in march 20 cutting, 30-40 days in April 20 cutting, and 30 days in May 20 cutting. 6. An asymptotic relationship was observed between plant population and leaf dry weight. Yield of dry leaf increased rapidly as plant population increased from 5,000 to 10,000 plants/10a with a reduced increasing rate from 10,000 to 20,000 plants/l0a, and levelled off at the plant population higher than 20,000 plants/l0a. 7. Stevia was adaptable in Suweon, Chengju, Mokpo and Jeju and drought was one of the main factors reducing yield of dry leaf. Yield of dry leaf was reduced significantly (approximately 30%) at June 20 transplanting compared to optimum transplanting. 8. Yield of dry leaf was higher in a vinyl house compared to unprotected control at long daylength or natural daylength except at short day treatment at March 20. Higher temperature ill a vinyl house does not have benefital effects at April 20 transplanting. 9. The highest content of stevioside was noted at the upper leaves of the plant but the lowest was measured at the plant parts of 20cm above ground. Leaf dry weight and stevioside yield was mainly contributed by the plant parts of 60 to 120cm above ground but the varietal differences were also significant. 10. Delayed harvest by the time of flower bud formation increased leaf dry weight remarkably. However, there were insignificant changes of yield as harvests were made at any time after flower bud formation. Content of stevioside was highest at the time of flower bud formation and earlier or later harvest than this time was low in its content. The optimum harvesting time determined by leaf dry weight and stevioside content was the periods from flower bud formation to right before flowering that would be the period from September 10 to September 15 in Suweon area. 11. Stevioside and rebaudioside content in the leaves of Stevia varieties were ranged from 5.4% to 14.3% and 1.5% to 8.3% respectively. However, no definit relationships between stevioside and rebaudioside were observed in these particular experiments.