• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.103-103
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• 2017

Vigorous root growth at the seedling stage in dry direct-seeded conditions is considered as a critical trait because it is involved in seedling emergence, early vegetative vigour, nutrient uptake as well as drought tolerance. In this study, we performed QTL mapping using the recombinant inbred lines obtained from the cross between Tongil-type Dasan and temperate japonica TR22183 (DT-RILs) to identify QTL underlying early root development. TR22183, which was previously reported to have high nitrogen utility and cold tolerance, showed vigorous root growth at the seedling stage in semi-drought conditions. Root length, fresh weight and dry weight of TR22183 were significantly higher than in Dasan. By QTL analysis with genotyping-by-sequencing method, we identified two QTLs for root fresh weight (RFW) in chromosome 7 and root dry weight (RDW) in chromosome 8, explaining phenotypic variances of 13.5% and 10.6%, respectively. These QTLs would be used to develop rice varieties adapted to direct-seeded cultivating system.

• Journal of Bio-Environment Control
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• v.11 no.1
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• pp.35-39
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• 2002

This study was conducted to investigate the effect of early $CO_2$ enrichment during seedling stage on long-term $CO_2$ enrichment after transplanting in the culture of pat-choi (Brassica campesris L), spinach (Spinacia oeracea L.), and leaf lettuce (Lactuca saliva L). During seedling stage, $CO_2$enrichment had significantly higher fresh and dry weight and leaf area of the top parts (above ground) of all three plant species than the control (no $CO_2$ enrichment). About 53%, 70% , and 40% increase in fresh weight of the top parts of pak-choi, spinach, and leaf lettuce were observed, respectively. Also, in seedling stage, dry weights of roots of spinach and leaf lettuce were significantly increased by early $CO_2$ enrichment. Relative fresh weight increment, compared with fresh weight of the control, in the top parts of roll three plants showed the highest values in 10 days after $CO_2$ enrichment treatment. In the long-term $CO_2$ enrichment experiment, early $CO_2$ enrichmented plants had 20% greater leaf area than the control in all three leafy vegetables. Fresh and dry weights of top parts of early $CO_2$-treated plants were also increased from 10 to 20%, as compared with the control plants. However, these increasement rates in the long-term $CO_2$ enrichment were lower than those seedling stage, which had 30-60% increment-rates. After transplanting, photosynthetic rate of each leafy vegetable in the control treatment slowly decreased, but those rates of early $CO_2$ enriched plants rapidly decreased.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.44 no.3
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• pp.236-242
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• 1999

To examine the seedling stand and growth as affected by early seeding dates of dry direct seeded rice in the Honam plain area of Korea, Dongjinbyeo was seeded at six seeding dates from early March to late April in rice fields of silty loam soil(Jeonbuk series) at the National Honam Agricultural Experiment Station (NHAES) for two years, 1996 and 1998. Seedling stand decreased slightly. with an early seeding date, but it produced more than the optimum seedling number except for the seeding of 25 March in 1996. Days to emergence was significantly longer, as seeding date was earlier, and days to emergence by early seeding was shortened only by 8 days because the mean air temperature was lower in 1996 than average, while in 1998, the reduction effect was nine to twenty five days because the mean air temperature was higher than average. In early seeding, various weeds occurred at the emergence date of rice and dominant weeds were Alopecurus aequailis, Ludwigia prostata and Rorippa islandica. NH$_4$$^{+}$ -N content in the soil at the 5th leaf stage and maximum tillering stage were lower, as the seeding date was earlier when nitrogen was split applied as basal and top dressed in 1996, while it was not significantly different among seeding dates when nitrogen was intensively applied as a top dressing in 1998. Tiller number at the maximum tillering stage and panicle number/m$^2$ were more, as seeding date was earlier in 1996, while it was not different in 1998. Filled grain rate and 1,000 grain weight was not different among the seeding dates. Milled rice yield was significantly decreased in the seeding before the middle of March, but in the seeding after late March, it was not varied when compared with the normal seeding date in 1996, while in 1998, there was no difference among seeding dates. From the above results, in consideration of seedling stand, weed occurance, rice growth and milled rice yield, the critical optimum early seeding time in the southern plain area may lie in early April. But it was suggested that when soil moisture is proper for seeding practices, seeding amount is increased and nitrogen is applied after plumule emergence of rice, milled rice yield may not be reduced in the seeding of middle or late March, compared with the seeding in April.l.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.31 no.3
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• pp.286-292
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• 1986

For the elucidation of saponin synthesis during ontogeny changes of ginsenosides and free sugars in seeds during stratification and seedlings in early growth stage were investigated with high performance liquid chrom-atography. Embryo plus endosperm at 40-day stratification showed 80% decrease of total saponin, disappear-ance of Rc, Rb$_2$ and Rb$_1$ and appearance of Rg$_3$ (probable) and 20-Glc-Rf (probable). Leaf ginsenoside F$_3$ was found not in fruit plup but seed and decreased during stratification. Both decomposition and synthesis of saponin seemed to occure during stratification. Ginsenosides in endosperm and embryo might be originated from fruit pulp by penetration. In seedling saponin appeared first in shoot and in root about one month later. Ginsenoside Rc, Rb$_2$, Rb$_1$ appeared in root at the last investigation (June 30) indicating normal saponin synthetic capacity of root. Saponin synthetic rate was twice in leaf than in root. Leaf ginsenoside F$_3$ was found in seedling root. Root saponin Rg$_3$ and 20-Glc-Rf were found in leaf and stem in seedling and decreased with growth suggesting that rate saponin is not such in certain growth stage. Total saponin content was negatively correlated with PT/PD in seeds and arial parts of seedling due to greater change of PD. than PT. Seed at 70days stratification showed high sucrose content. In seedling glucose was main sugar in stem all the while and sucrose in root at early stage while glucose, fructose and sucrose were found in leaf.

• The Korean Journal of Ecology
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• v.15 no.3
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• pp.297-309
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• 1992

The growth of digitaria adscendens and eleusine indica, annual weeds common in japan, was experimentally analyzed under varying untrient conditions. compared with e. indica, d. adscendensshowed a higher the two under high nitrogen availability. Higher net assimilation rate(nar) in d. adscendens than e. india was responsible for high RGR in D. adscendens under the low nitrogen availability. The different of NAR in the two species was induced not by leaf nitrogen content but by nitrogen use efficiency. Under unfertilized conditions nitrogen uptake rate(nur) was greater in d. adscendens than e. indica. Specific absorption rate in two species was similar, but root mass was greater in d. adscendens than e. indica.d. adscendens allocated more dry matter to roots than e. india earlier stage of seedlings. The contributed to higher rot mass and in turn resulted in higher nur in d. adscendens than that in e. india. It is concluuded that the larger allocation of dry matter to roots at early seedling stage in d. adscendens plays an important role in obtaining nitrogen for the continuation of growth under low nitrogen availability.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.44 no.2
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• pp.149-153
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• 1999

Prediction of rice developmental stage is necessary for proper crop management and a prerequisite for growth simulation as well. The objectives of the present study were to find out the relationship between the plastochrone index(PI) and the developmental index(DVI) estimated by non-parametric phenology model which simulates the duration from seedling emergence(DVI=0) to heading(DVI=l) by employing daily mean air temperature and daylength as predictor variables, and to confirm the correspondency of developmental indice to panicle developmental stages based on this relationship. Four japonica rice cultivars, Kwanakbyeo, Sangpungbyeo, Dongjinbyeo, and Palgumbyeo which range from very early to very late in maturity, were grown by sowing directly in dry paddy field five times at an interval of two weeks. Data for seedling emergence, leaf appearance, differentiation stage of primary rachis branch and heading were collected. The non-parametric phenology model predicted well the duration from seedling emergence to heading with errors of less than three days in all sowings and cultivars. PI was calculated for every leaf appearance and related to the developmental index estimated for corresponding PI. The stepwise polynomial analysis produced highly significant square-rooted cubic or biquadratic equations depending on cultivars, and highly significant square-rooted biquadratic equation for pooled data across cultivars without any considerable reduction in accuracy compared to that for each cultivar. To confirm the applicability of this equation in predicting the panicle developmental stage, DVI at differentiation stage of primary rachis branch primordium was calculated by substituting PI with 82 corresponding to this stage, and the duration reaching this DVI from seedling emergence was estimated. The estimated duration revealed a good agreement with that observed in all sowings and cultivars. The deviations between the estimated and the observed were not greater than three days, and significant difference in accuracy was not found for predicting this developmental stage between those equations derived for each cultivar and for pooled data across all cultivars tested.

• Korean Journal of Weed Science
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• v.30 no.2
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• pp.103-110
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• 2010

This experiment was conducted to investigate seedling emergence and early growth of Monochoria vaginalis and Scirpus juncoides in the controlled-environment chamber maintained at different temperatures. Non-linear regression analyses of observed data against effective accumulated temperature (EAT) with the Gompertz and logistic models showed that the Gompertz and logistic models worked well in describing seedling emergence and early growth of both weed species, respectively, regardless of temperature. EATs required for 50% of the maximum seedling emergence and the maximum leaf number of M. vaginalis were estimated to be 69.3 and $131^{\circ}C$, respectively, while those of S. juncoides were 94.8 and $137^{\circ}C$, respectively. Models developed in this study thus were used to predict seedling emergence and early growth under elevated temperature condition. If rotary tillage with water is made on 27 May under $+3^{\circ}C$ elevated temperature condition, dates for 50% of the maximum seedling emergence and 4 leaf stage were predicted to be 1 June and 15 June for M. vaginalis and 3 June and 14 June for S. juncoides, respectively. As compared with current temperature, these dates are 1-2 days earlier for the seedling emergence and 3 days earlier for the early growth, suggesting that earlier application of herbicides is required for effective control of M. vaginalis and S. juncoides under elevated temperature condition in the future.

• Horticultural Science & Technology
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• v.19 no.3
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• pp.329-333
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• 2001

The study was performed to investigate the effect of a plug culture method in the early stage of a potato breeding program. The 105, 200 and 288-cell plug trays were used for raising potato seedlings. The % germination in plug trays ranged between 94 and 96%. Percent tuberization measured at 50 and 60, and 70 days after sowing was the greatest in 105-cell and 200-cell trays, respectively. However, tuberization was most delayed in 288-cell trays. Thus, it is considered that 105-cell tray is the most effective for the selection of early maturing plants. Plant maturity was determined by the morphological characteristics at the seedling stage of stolons cultured in plug trays. Most of seedlings with shorter stolons at seedling stage (1st generation) were the early-maturing, while most of seedlings with longer stolons were the late-maturing at the clonal stage (2nd generation). These results mean that the plant maturity in the early potato breeding program can be effectively grouped by observing the morphological characteristics of stolons after plug culture.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.4
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• pp.286-291
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• 2002

Seedling establishment of soybean [Glycine max (L.) Merr.] is a critical factor in production system and cultural practices. The objective of this study was to identify the components of soybean seedling developments encompassing planting dates and cultivars that respond to emergence, early growth stage and dry matter accumulation. Three soybean cultivars, Hwangkeumkong, Shinpaldalkong 2, and Pungsannamulkong, were planted at Baegsan silty loam soil. Planting date was May 13, June 3, and June 24 in 2001. Sprinkler irrigation was accompanied with 30mm after seeding for three planting dates. Soybean seedlings were sampled at the growth stages from VE to V5. Days to emergence of soybean seedlings were taken 8 at May 13 and 5 at June 24 plantings. Emergence percentage was over 90 at three planting dates. May 13 planting took 33 days and June 24 planting was 25 days for reaching V5 growth stage. Cotyledon number was decreased after V2. Significant cultivar difference was found in cotyledon dry weight until V2 which differed in seed dry weights at the planting times. Leaf and total dry weights of soybean seedlings were not differed from V1 to V3 among planting dates and cultivars. Leaf water contents were generally ranged 78 to 85%. Branch was appeared from V4. Leaf/stem ratio among cultivars was similar at five growth stages and gradually increased from 2.1 at V1 to 2.8 at V5. The results based on this experiment indicated that seedling establishment of soybean was continued from VE to V3 growth stages affecting mainly by planting date and soil moisture.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.18 no.3
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• pp.79-95
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• 2015

To suggest ecological management plans for invasion of Salix gracilistyla, stepwise environmental sieve of seed dispersal, germination, seedling and juvenile stages were investigated. About 84% of total seeds were released between May 6 and 10. Germination rates significantly declined with decrease of light intensity from 100% to 30% and 0% (p<.001), but above 60% of seeds germinated in all treatments. Difference of germination rates with 0 and 2cm water level was not significant (p = .571). With increase of elapsed time after seed dispersal, germination rates significantly decreased (p<.001), and seed viability was lost within 16 days. Considering both germination rate of seed and survival rate of seedling, survival rate of all dispersed seeds was only 5% when 8 days passed after seed dispersal. All 22-day-old seedlings (height: 1cm) died under flooding of twice level as its height. With decrease of light intensity from 100% to 30%, survival rates of seedling decreased from 90% to 33% (p<.001). In the case of 45-day-old juvenile (height: 20cm), survival rate was 70% under the water level same as its height. There was significant interactive effect of water level and light intensity on the growth of juvenile (height: p<.001, dry weight: p<.01), and survival rate of juvenile was 10% under +20cm-water level and 30%-light intensity condition. The following management plans for invasion of S. gracilistyla are recommended from these results. (1) Dry condition should be maintained at fringe of wetlands for about two weeks at seed dispersal and germination stage (early May~mid May). (2) Water level should be raised to about 5cm at fringe of wetlands for about two weeks at seedling stage (mid May~early June). (3) Water level should be raised to over 20cm at fringe of wetlands for a long time at juvenile stage. Planting trees for shading can raise management effectiveness (mid June~). (4) As water level manipulating is performed as fast as possible for controlling seedling and juvenile, management become easier and more effective.