• KOREAN JOURNAL OF CROP SCIENCE
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• v.39 no.3
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• pp.205-210
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• 1994

This experiment was conducted to investigate of soil hardening degree before sowing, furrow depth at sowing and flooding time after sowing at furrowing in flooded rice paddy field that many people have an interest in as direct sowing method most recently. As hardening period was increased, the percentage of seedling stand and seed floating at flooding were increased slightly, while buried depth of stem at maximum tillering stage and cone penetration depth were decreased, respectively. Therefore, optimum degree of soil hardening was about 3 days after draining, at this time, cone penetration degree was about 6~7cm. According to furrow depth was more and more deep, buried depth of stem was increased gradually, but percentage of seedling stand was decreased considerbly. Also, root distribution ratio on surpace horizon and lodging degree were increased gradually according to furrow depth become more and more shallow. As flooding time after sowing was late, percentage of seedling stand and panicle number per $m^2$ were decreased slightly. These results apparently indicated that sowing after 3 days hardening when cone penetration degree was 6~7cm, furrow depth 3~4cm degree and flooding time just after sowing the best method to good establish of seedling stand.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.4
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• pp.424-428
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• 1997

This study was carried out to investigate the effects of sowing dates, Apr. 25, May 15, June 5 and June 25, on sex ratio, growth and seed yield of "Chonnam species", local variety of hemp plant. The results were following as. : In sex ratio according to the different seeding dates, the revealating rate of female and male plants were highest on June 25, and Apr. 25, respectively. The length of stem, the number of branches, nodes, and seed yield were increased on May 15, but these charateristics were rapidly reduced on June 25 because of short growing period. Yield of seeds was increased by 24％ on May 15 comparing with 1.30ton /ha on Apr. 25.

• Journal of Biosystems Engineering
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• v.28 no.6
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• pp.531-536
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• 2003

This study was carried out to develop a vacuum nozzle seeder for large seeds and performance was tested on seed feeding, arranging. and sowing peformance. The results of this study were as follows： The operation of feeding device of the seeder was programmed to operate a period of setting time after sowing 6 rows. The setting time was decided based on a discharged seed by the angular speed of feeding roller. The arranging accuracy of 'tuktozwa', 'hukjong' and 'chambak' was 96.4％, 95.2％ and 89.4％ respectively. The working performance was 75.6sheet/hr which was 3.8 times higher than that of manual work. An average seeding rate of 1 grain was 97.8％.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.61 no.3
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• pp.208-214
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• 2016

This study was conducted to evaluate the effects of different sowing times (May 25, June 10, June 25, July 10, and July 25) on growth and yield of four proso millet (Panicum miliaceum L.) cultivars (Hwanggeumkijang, Manghongchal, Ibaekchal, and Hwangsilchal) at a cultivation area in Iksan, Jeonbuk Province. Heading and ripening times were delayed, with later sowing times in all cultivars, and the periods for heading and ripening were shortened. For sowing from May 25 to July 25, the growth stage was shorter by 40 days in Manghongchal, 38 days in Hwanggeumkijang, 36 days in Hwangsilchal, and 30 days in Ibaekchal. The culm length, ear length, ear width, and culm diameter differed significantly between the cultivars and sowing times. In particular, the culm and ear lengths were considerably reduced when the sowing time was delayed. The grain yield (kg/10a) of Hwanggeumkijang and Ibaekchal was 312 and 359 kg, respectively, for sowing on June 10; and that of Manhongchal and Hwangsilchal was 286 and 404 kg, respectively, for sowing on June 25. Thus, the optimum sowing time was June 25 for Hwanggeumkijang and Ibaekchal, and June 10 for Manhongchal and Hwangsilchal.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.66 no.1
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• pp.80-86
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• 2021

The purpose of this study was to determine the optimal sowing date for the spring sowing cultivation of rapeseed (Brassica napus L.). To determine suitable rapeseed sowing dates for spring sowing cultivation, changes in growth, flowering characteristics, and seed production were investigated in Muan, South Korea between 2019 and 2020. 'Jungmo7001' is the suitable variety for spring sowing because of its early flowering characteristics, high seed yield, and the fact that it occupies the highest cultivation area in South Korea. When the yield of 'Jungmo7001' was investigated in 2019 and 2020, the highest yields recorded were 243 kg/10a in February 28, 2019, and 294 kg/10a in February 18, 2020. As a result, the optimal rapeseed seeding period is considered to be mid-to-late February in the southern region. There was no statistically significant difference in seed crude oil content. The content of oleic acid (C18:1) decreased, but that of linoleic acid (C18:2) and of linolenic acid (C18:3) increased significantly depending on the sowing date.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.48 no.6
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• pp.447-451
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• 2003

When sowing green peas in the autumn, proper seedling stands and growth quantity should be secured before winter begins. Also, for proper acclimatization, injuries caused by low temperatures, frost or high temperatures in the P.E. film during mulching, should be avoided during the regeneration period; that being early spring. The days required for growth in each stage in Yeosu are shorter than those in Naju because Yeosu has high temperatures during the growth period. Furthermore, in Yoesu, it was observed that there were more effective branches as well as effective and attached node positions on the branches. The first pods on the main stems and effective branches were observed to be higher than those in Naju. The number of pods per plant and the number of seeds per pod in Yoesu was greater than for those in Naju and the pod length was longer as well. Considering the missing plant rate, growth, and green pod yield, the optimum sowing date for the green pea was mid-November in both location. The stable acclimatizing date for the green pea was early March when the highest yield can be acquired due to a lot of effective branches and pods per plant and with the lowest missing plant rate and rate of injury in acclimatization.

• Journal of The Korean Society of Grassland and Forage Science
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• v.43 no.2
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• pp.103-108
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• 2023

Due to the recent impact of global warming, heavy rainfall and droughts have been occurring regardless of the season, affecting the growth of Italian ryegrass (IRG), a winter forage crop. Particularly, delayed sowing due to frequent heavy rainfall or autumn droughts leads to poor growth and reduced winter survival rates. Therefore, techniques to improve yield through additional sowing in spring have been implemented. In this study, the growth of IRG sown in Spring and Autumn was compared and analyzed using vegetation indices during the months of April and May. Spectral data was collected using an Unmanned Aerial Vehicle (UAV) equipped with a hyperspectral sensor, and the following vegetation indices were utilized: Normalized Difference Vegetation Index; NDVI, Normalized Difference Red Edge Index; NDRE (I), Chlorophyll Index, Red Green Ratio Index; RGRI, Enhanced Vegetation Index; EVI and Carotenoid Reflectance Index 1; CRI1. Indices related to chlorophyll concentration exhibited similar trends. RGRI of IRG sown in autumn increased during the experimental period, while IRG sown in spring showed a decreasing trend. The results of RGRI in IRG indicated differences in optical characteristics by sowing seasons compared to the other vegetation indices. Our findings showed that the timing of sowing influences the optical growth characteristics of crops by the results of various vegetation indices presented in this study. Further research, including the development of optimal vegetation indices related to IRG growth, is necessary in the future.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.2
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• pp.67-72
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• 2005

Overwintering capacity, closely related to winter hardiness, of Chinese milk vetch planted with different sowing times and sowing practices was investigated to improve the incorporation into cropping system in Korea. The tolerance to low temperature was evaluated with $LT_50$ using leaf disc leaching method. Dry weight of CMV was reduced remarkably with delayed planting from Sep. 5 to Oct. 20. The differences in tolerance to freezing temperature were not conspicuous among CMV genotypes, however, the differences between genotype (collections at different regions) were due to the plant architecture, mainly to the leaf angle. The crouching genotype collected at central region of Korean peninsula, which showed excellent freezing tolerant, has planophile leaves. The feature of internal constituents of CMV genotypes did not show any noticeable differences with respect to the freezing tolerance which evaluated by leaf disc leaching experiment. To overcome the poor overwintering capacity, tolerant genotype should be developed by selection with considering the plant architecture. The reduction of CMV growth during overwintering period was ameliorated with furrow-sowing under late-sown condition, therefore, when the CMV is inevitably sown late after recommended time, the seeds should be sown on furrow to overcome the cold stress.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.24 no.2
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• pp.65-73
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• 1979

Experiment was conducted to study the optimum sowing date and nursery duration at Jean An from 1976 to 1978 and their influence on the growth, dry matter production during growth period of the rice plant. In case of Tongil lines, the lengthening of nursery duration and late sowing increased unexpected heading and prolonged heading and maturing period. High yield were obtained by increasing dry matter accumulation during growth period of rice plant. To obtain safe yield in Tongil lines transplanting must be done before May 30th.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.65 no.3
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• pp.241-247
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• 2020

Sesame is typically a temperature- and day length-sensitive plant, as its flowering is promoted under high temperature and shorter day length conditions. The experiment carried out in the present study revealed that day length influenced sesame flowering to a much greater extent than temperature. The degree of day length influence differed depending on the sesame variety. Days from sowing to flowering was negatively correlated with yield-related characteristics such as stem length, capsule number per plant, 1,000 seed weight, and seed weight per 10a. In cases where the period from sowing to flowering was longer and flowering date was later, the reproductive growth period was shorter during maturity. Analysis of the effects of temperature and day length on seed yield production revealed that temperature was a much more influential factor than day length. However, day length was more influential than temperature under low temperatures, such as 22℃. All varieties apart from Ansan were shown to be primarily influenced by temperature. Sesame varieties were grouped in view of optimal seed sowing time through principal components analysis. The Poongsung and Sungboon varieties favored early sowing under low temperatures and short day lengths. The DT45, Poongsung, 90 days, Ansan, and Sungboon varieties favored late sowing under high temperatures and long day lengths. The Yangbaek and Arum varieties could be sown both early and late.