• KOREAN JOURNAL OF CROP SCIENCE
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• v.41 no.1
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• pp.28-33
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• 1996

This experiment was carried out at National Crop Experiment Station in 1994 to obtain basic information of growth characters and yield of rice under various seeding methods in direct seeding on dry paddy. Hwaseongbyeo sown on April 27 by flat drill seeding, high ridged drill seeding and hill seeding under different seed conditions, soil convering after seeding and irrigation methods. Nitrogen applied 150kg /ha by 3 times split application at rate of 40:30:30％ (basal: 5th leaf stage:panicle initiation stage). Seedling stands were higher in flushed irrigation water after seeding than in irrigation at 3rd leaf stage, and it also was higher in high ridged drill seedings than in flat drill seedings. Days for seedling stand, heading date were shorten 6~10 days, 2~3 days by flushed irrigation water after seeding, respectively. Number of tiller was more in high ridged drill seedings than conventional seedling method(Flat drill seeding ＋ intact seed ＋ soil covering after seeding ＋ irrigation at 3rd leaf stage after seedling stand) at early growth stage, but the most tiller number was highest in developed seeding method(Flat drill seeding ＋ soaked seed ＋ non soil covering after seeding ＋ fulshed irrigation water after seeding) at heading stage among used seeding methods. Lodging index was slightly high in high ridged drill seeding and conventional seeding. Field lodging was degree 1 in high ridged drill seedings and developed seeding, Milled rice yield in developed seeding was increased 7％ compaired with conventional seeding(5.35t /ha).

• Journal of Korean Society of Forest Science
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• v.57 no.1
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• pp.1-7
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• 1982

The simple logistic growth model on the logistic curve, being originally a kind of population growth curve has also been sometimes utilized to describe growth curves in herbaceous plants such as duckweed and sun-flowers. It has already been recognized that the agreement between the theoretical calculations and the empirical observations is quite satisfactory form a practical point of view. It remains, however, still doubtful whether the logistic curve could be applied to the growth or ordinary woody plants which is quite different in its character from that of herbaceous plants. In this study, the simple logistic model, being a basic tool of stand density management, is applied to yield data from pine stands in order to test the adequacy of the model An attempt of testing the significance of the fit is made by applying the Chi-square test.

• Journal of Forest and Environmental Science
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• v.13 no.1
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• pp.66-80
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• 1997

Pinus koraiensis is one of the major speciese which have been recently planted for ten years and consists of 31% of total plantation. Presently young stand less than 30 years consists of 87% of total forest, but tending thinning of it is hardly carried out and the desirable direction for the thinning is not established yet. The objective of the study is to introduce the optimum thinning plan and thinning method through the long-run experiment of tending thinning for the Pinus koraiensis stand. The experiments carry out to interprete its growth model on the subject of two thinning experimental plots and yield table of Pinus koraiensis. As the basic step for understanding the thinning process, a theoretical growth model which is suitable to express the growth process is required. For that purpose, three growth functions (Mitscherlich, 4 parameter Richards, 3 parameter Richards) are applied to the diameter growth of the sample trees which are taken in the two plots. The results show that 3 parameter Richards is the most suitable. It is also verified that the diameter growth, the height growth, and the decrease in the number of stocks can be estimated by this function. To estimate the growth change of single tree, growth model including parameter h which is related to the occupation area of single tree are introduced. The parameter h can be estimated by using the data of the diameter growth obtained from the established experimental plots. Therefore, if both verification and modification of the usefulness of the model suggested is made, equations which tell about the thinning effects could be drived by estimating the growth process of single tree in advance.

• Journal of Crop Science and Biotechnology
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• v.11 no.3
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• pp.193-198
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• 2008

To develop a natural re-seeding technology, the optimum soil incorporation time of Chinese milk vetch(CMV) plant residues, seed persistence in soil, biomass production and subsequent rice yield were determined from 2005 to 2007 in rice with CMV green manure in southern Korea. Generally, insufficient seedling stand was regenerated with CMV incorporation to the soil at 20 and 25 days after flowering(DAF), while high regeneration of greater than 400 seedlings per $m^2$ was observed at 35 and 40 DAF. High re-seeding stand of CMV incorporated at 35 DAF or later was related with high seed viability and heavy seed weight. Appreciable number of CMV seeds remained 4 month after burial in soil and a good number of CMV seedlings regenerated from this seed bank at rice harvest time in the fall. Based on the relationships among re-seeding number of CMV plants, seed weight and seed viability, CMV plants should be incorporated into the soil 35 DAF(May 30) or later when CMV seeds were sufficiently matured. The natural re-seeding stand for the 3-year trials was stable ranging from 437 to 700 plants per $m^2$ and the biomass production was sufficient to supply nitrogen for rice growth. The use of re-seeding CMV plant can produce similar rice yield like that of rice without CMV green manure.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.28 no.4
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• pp.481-487
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• 1983

The need to synchronize flowering in two lines of different maturities is frequently encountered in hybrid com (Zea mays L.) seed production. To establish the methods for synchrony of flowering in parent lines of different maturities be effects of clipping at 4 and 6-leaf stages of growth and two levels, clear polyethylene mulching and five different planting dates on flowering date growth and seed yield of two dent com inbred lines of different maturities were evaluated Clipping just above the shoot-apex delayed pollen sheeding 6 to 9days and silking 5 to 13 days but reduced stand and seed yield 30 to 70% and 67 to 81%. respectively. Clipping 5cm above the shoot apex delayed flowering 1 to 4 days without stand reduction but reduced yield 3 to 29%. Laterclipping was slightly more effective for delaying flowering than earlier clipping but reduced stand more severely when clipped just above the shoot apex. Under clear polyethylene film mulching, flowering of two lines was 13 to 15 days earlier and seed yield of B68 (late line) was significantly increased. As planting was delayed from April 18 to June 13, the number of days from planting to flowering of two lines decreased due to increase in air temperature. However, growing degree days (GDD) from planting to flowering of each lines was similar regardless planting dates indicating that GDD can be satisfactoryly used for choosing the planting dates of parent lines of different maturities. Seed yields of two lines were decreased with delaying planting dates.

• Journal of Korean Society of Forest Science
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• v.107 no.2
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• pp.174-183
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• 2018

This study aims to make the stand density management diagram which is useful for establishing stand density management system in Chamaecyparis obtusa forest. By using 216 sample plots to estimate Yield-Density relationship ($R^2=0.743$), the stand density management diagram was modeled by the estimated parameters. As a result of this diagram, after planting 3,000 trees per hectare the mortality rate of this unthinned C. obtusa stands over 80 years was estimated to be equal to $12.0{\sim}18.1trees{\cdot}ha^{-1}{\cdot}year^{-1}$, and stand volume was $463.1{\sim}695.4m^3{\cdot}ha^{-1}$, and stand density was $1,555{\sim}2,038trees{\cdot}ha^{-1}$. Developed stand density management diagram for C. obtusa is effective to establish the management criteria and production objective. Therefore, this study allowed us to make the optimal forest working plan.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.38 no.2
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• pp.166-173
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• 1993

Seed infection to pod and stem blight (Diaporthe phaseolorum) is severe at summer type soybeans maturing at hot and humid conditions. In order to increase germination and plant stand, this experiments were evaluated the effects of fungicide Benoram(Benomyl 20% ${\pm}$ Thiram 20%) seed treatments with different seed sizes on emergence yield at field conditions, and with different infection degrees to pod and stem blight on germination in laboratory. Benoram treatment on seed was improved emergence rate and elongated hypocotyl not increased growth and yield. It was clearly improved length but germinations and germination speed by Benoram fungicide treatment on severely infected seed however was not improved germination rate at good quality of seeds and the effect was higher at large seed cultivar than small ones.

• Journal of Korean Society of Forest Science
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• v.113 no.1
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• pp.131-142
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• 2024

The purpose of this study was to estimate the optimal stand density criteria for each growth stage of Chamaecyparis obtusa (Siebold & Zucc.) Endl. to achieve the timber production goal for cypress forests and develop an optimal silvicultural system for forest thinning. A relative yield index (Ry) value of 0.75, presented as a stand density management criterion index, was estimated by analyzing the relationship characteristics between the composition ratio and stand density of slender trees from 216 sample plots of the recruited cypress forests. The analysis of the feasibility of achieving each production target in the existing silvicultural system for C. obtusa revealed that the growth rate according to the parameters of forest land productivity, such as site index and thinning intensity according to the increase in age, was not properly reflected. In the thinning system for each timber production target analyzed in this study, 353 high-quality large hardwoods from 498.1 m³/ha, 703 high-quality medium hardwoods from 376.2 m³/ha, and 1,758 small-diameter hardwoods from 249.5 m³/ha could be harvested. Although the silvicultural system prepared on the basis of the results of this study cannot be uniformly applied according to various management goals, this study is meaningful in that it presents empirical reference standards based on the stand density management diagram that reflects the growth characteristics of cypress forests in South Korea.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.40 no.1
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• pp.86-91
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• 1995

This experiment was conducted to understand the response on sowing rates at furrow sowing of rice in paddy field. As sowing rates was increased, the number of seedling stand per$m^2$ was icreased, while panicie number per plant was decreased slightly. Leaf area at heading stage and effective tiller ratio were decreased with increasing of sowing rates, but heading date was not defferent among sowing rates. According to sowing rates was increased, culm length, panicle length, breaking strength, culm diameter were decreased, while lodging index was increased. Also, field lodging was observed in the higer sowing rates over 5kg/l0a. Althougth the panicle number per $m^2$ was increased with increasing of sowing rates, spike let per panicle and percent of filled spikelet were decreased. According to the result from the path coefficient analysis, percent of filled spikelets well identified to be the most influential variables on the variability in rice yield, so that improving percent of filled spikelets by inhibition of field lodging was the important matter to increase the yield. The optimal sowing rate and the number of seedling stand were estimated to be 4.5kg/l0a and 105 per $m^2$ respectively.

• Korean Journal of Soil Science and Fertilizer
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• v.49 no.6
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• pp.662-668
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• 2016

No-tillage dry-seeding of rice can offer potential benefits by reducing time and labor cost compared with conventional tillage practices. This study was conducted to investigate the effects of no-tillage dry-seeding on rice growth and soil hardness in comparison with other rice cultivation methods, machine transplanting and wet-hill-seeding on puddled paddy. The seedling stand fell within optimum range for both no-till dry-seeding and wet-hill-seeding on puddled paddy. Plant height, number of tillers and SPAD values in no-tillage dry-seeding cultivation were higher than those observed in other methods. There were no significant differences in grain yield of rice among three cultivation methods. The quality characteristics of milled rice grown in no-tillage dry-seeding were similar to those grown in other cultivation methods. Soil hardness in top 10 cm depth was significantly higher in no-tillage dry-seeding than other cultivation methods, while soil hardness below 10 cm depth was highest in machine transplanting cultivation. Results indicate that no-tillage dry-seeding practice is comparable to conventional tillage system in terms of seedling establishment, growth, yield and grain quality.