• KOREAN JOURNAL OF CROP SCIENCE
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• v.58 no.1
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• pp.57-66
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• 2013

The purpose of this study was to investigate the effects of shifts in sowing time on the ecological responses, growth and yields of major soybean cultivars in a southern region of South Korea. Experiments were carried out in Naju, Jeonnam Province (latitude $35^{\circ}$ 04'N, longitude $126^{\circ}$ 54'E) for three years from 2008 to 2010. The test cultivars included Saeol-kong and Tawon-kong of the summer type, Taekwang-kong and Pungsannamul-kong, and Cheongja3 of the autumn type. Sowing took place on May 15 and 30, June 15 and 30, and July 15 of each year. Of the summer type soybean cultivars, Saeol-kong showed a smaller curtailment in days from sowing to flowering, days from flowering to maturity, and days from sowing to maturity according to sowing time postponement than Tawon-kong. Of the autumn type soybean cultivars, Taekwang-kong exhibited a lower photoperiodic response in reproductive growth period than Pungsannamul-kong and Cheongja3, both of which recorded higher level photoperiodic responses in vegetative growth stages and reproductive growth periods than other test cultivars, with the former exhibiting higher levels than the latter. Most of the test cultivars tended to decrease in stem length, node numbers of the main stem, and stem diameter according to postponed sowing time, but there were no significant differences in stem length and node numbers of the main stem of the Saeol-kong cultivar. Differences in sowing times did not affect the first setting pod node order of Saeol-kong and Tawon-kong summer type cultivars of internode lengths of all of the test cultivars. All of the test cultivars tended to show decreases in pod number per plant due to postponement of sowing time except for the Saeol-kong cultivar. The variation was more prominent in small grain cultivars such as Tawon-kong and Pungsannamul-kong with the latter autumn type cultivar showing especially large variation. Yields were the greatest for the Tawon-kong, Taekwang-kong, and Pungsannamul-kong cultivars sown on May 30 and Cheongja3 sown on May 30 and June 15. There were no significant differences in the yields of Saeol-kong for different sowing times from May 30 to July 15, with the yields lowest for the batch sown on May 15.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.65 no.4
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• pp.477-484
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• 2020

This study was conducted to investigate the effects of slow-releasing fertilizer and sowing date on waxy corn propagated through double cropping without tillage. "Mibaek 2" was sown for first cropping on March 25^th, April 5^th, and April 15^th, and for second cropping on July 5^th, July 15^th, and July 25^th in 2018-2019. In order to save labor, slow-releasing fertilizer was utilized only one time before sowing. The accumulated temperature from sowing to silking was about 590-700℃. It took 65-77 days when "Mibaek 2" was sown in early April, but the one sown in early July took 42-52 days. In the first cropping, the culm length and ear length caused by the sowing date had no statistical significance, but the kernel set length was the highest at 123 cm in the sowing district on April 5^th. The weight of marketable ears was the highest at 100%, in addition to soil testing-based recommended fertilization. Meanwhile, in the second cropping, culm length, ear length, and yield were less compared to the first cropping. The culm length, kernel set length, ear length, and seed set length decreased as sowing date was delayed. The number and yield of marketable ears were the highest at 100%, in addition to soil testing-based recommended fertilization like in the first cropping. It has been found that securing yield by July 15^th to finish the second seeding of the crop in the central part of Korea is advantageous. These results of this study will be helpful to farmers for the double cropping of waxy corn cultivation and management.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.26 no.2
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• pp.179-184
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• 1981

The study was conducted to know the differential growth responses of soybean cultivars as affected by various application stages of Metribuzin herbicide, at the University experimental farm of Chonnam Nat'l. Univ, Kwangjoo, 1980. Experimented soybean materials were six cultivars, as Kwanggyo, Dongbuktae, Bongui, Yukwoo 3, Suweon 85, and Suweon 86., . and Laid-out application stages were five as pre-sowing, Pre-emergence, Early Post-emergence, and Late Post-emergence treatment comparing with Control. Results obtained from the study were as follows: Among experimented soybean cultivars, no significantly tolerant cultivar was shown. Highly significant differences in phytotoxicities by Metribuzin treatments were detected among various application stages, and crop tolerances were recognized bigger in order as E. Post-emg. < L. Post-emg. $\ll$ Pre-emg. < Pre-sowing $\leq$ Control. The phytotoxic symptoms of all soybean cuitivars were severely recorded in order of Leaf No. /Plant < Plant height $\ll$ Branch No. /Plant. For the cultivation of most soybean cuitivars, the use of Metribuzin in Pre-sowing or Pre-emergence were recommended, and especially it is expected to follow of more detailed study on soil-incorporation method in Pre-sowing treatment, and rather the tank-mixture system of Metribuzin with others than the mono-application system for the safe-use and enlargement of weeding-spectrum.

• 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.

• Journal of Biosystems Engineering
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• v.21 no.3
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• pp.306-314
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• 1996

A seeder monitoring system was developed to solve the problems of mis-sowing and tube clogging in direct seeding machines, which have been one of the factors that reduce the performance of sowing operations. The system consisted of photo sensors, air nozzles, an air compressor, and a one-chip micro-computer based controller. The system was also equipped with the devices that perform the functions of self-checking and intermittent air injection for cleaning seed tubes. The performance of the system was tested in the laboratory and field. Using the well-cleaned rice seed, the average time for checking the mis-sowing was 1.37 seconds in the field and 1.2 seconds in the laboratory without any malfunction. Overall evaluation of the system indicated that the system can be utilized for seeding machines not only for paddies but beans and corns.

• 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 Weed Science
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• v.18 no.2
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• pp.116-121
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• 1998

Field experiment were carried out to elucidate the changes of weed occurrence according to the sowing time and to establish the efficient weed control system in dry seeded rice cultivation. E crus-galli and D. sanguinalis are tow major weeds at the earlier sowings, but C. difformis was dominating at the later sowing. In the case of E. crus-galli, there was a tendency of gaining its dominance values as the rice growth stage advances. The later the sowing time was, the more weeds occurred at the early rice growth stages: However, when measured at heading, total dry weight was greater at the earlier sowings. Yield loss due to weeds were also greater at the earlier sowings. Community diversity of weeds was greater at the later sowings, while specific weed was gradually dominating as rice growth stage advances, regardless of sowing time. When herbicides were applied before 15 DAS, weeds were effectively controlled only upto 35 DAS. So systemic herbicide application, one on 0 to 10 DAS and the other on just after flooding, appeared to be recommendable in direct seeded rice cultivation.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.60 no.2
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• pp.197-211
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• 2015

In order to investigate optimum and marginal sowing date of foxtail millet, proso millet and sorghum in middle area (Anseong, Gyeonggi province) of korea, four levels of sowing date [(May 15(1st), June 6(2th), June 26(3th), July 13(4th)] with mulching and non-mulching were treated in this experiment. We used three crops of foxtail millet, proso millet and sorghum with four varieties of Samdachal, Samdamae, Kyeongkwan1, Hwanggeumjo in foxtail millet, Leebaekchal, Manhongchal, Hwangsilchal, Hwanggeumgijang in proso millet and Nampungchal, Hwanggeumchal, DS202, Moktaksusu in sorghum achieved from RDA. In culm length, sowing date of June 26 was the highest in all varieties of foxtail millet, proso millet and sorghum. Sowing date of May 15 showed the highest ear length in foxtail and proso millet, whereas the highest ear length was obtained from sowing date of June 26 in sorghum. In numbers of leaf, sowing date of May 15 showed the highest in all three crops of foxtail millet, proso millet and sorghum. Days from sowing to heading date were reduced in Samdamae, Kyeongkwan1 and Samdachal as sowing date was late. In Hwanggeumjo it was reduced from the sowing date from May 15 to June 26, but it was same days was taken between June 26 and July 13 sowing date. Days from sowing to heading date of four varieties in proso millet were reduced as sowing date was late. Days from sowing to heading date in sorghum were reduced as sowing date was late, whereas it was increased the $4^{th}$ sowing date of July 13. There were no significant differences in growth and yield characteristics between mulching and non-mulching in four varieties of foxtail millet, proso millet and sorghum with four varieties. The highest grain numbers per panicle, 1000 grain weight and yield per 10a were obtained from sowing date of June 26 in four varieties of foxtail millet, proso millet and sorghum. In sowing date of July 13, all varieties of foxtail millet, proso millet and sorghum were not able to be ripened because of late sowing except Hwnaggeumjo, Manhongchal and Hwanggeumgijang.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.2
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• pp.30-37
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• 1964

Experiments were carried out to clarify the relationships between seed yields and some ecological characteristics, seed yields and some morphological characteristics, and the relationships among the varietal yields on the several sowing plots when grown under different climatic conditions. Twenty-four soybean varieties were used as the material, selected at random from 138 varieties which were cultivated the year before. These varieties were grown in the Experimental Farm, Chinju Agricultural College, Kyung Sang Namdo, Korea, and seed sowing was conducted at 5 times, from April to July, in 1962 and 1963. The results obtained are summarized as follows: 1. Correlations between seed yields and some ecological characteristics on the sowing date bases are shown in Table 1. Among some ecological characteristics, it was observed that there wert close relationships between seed yields and days to flowering, and between seed yields and the total growing length, except on the late sowing, i.e. July sowing plots, However, there was no clear correlation between seed yields and durations of flowering, and between seed yields and days from flowering to maturity. 2. Correlations between seed yields and some morphological characteristics on the sowing date bases are shown in Table 2. From this table, it was also observed that there were some close relationships between seed yields and branch number for plant, stem diameter, plant weight, pod number per plant, and grain number per plant, but there was no clear relationship between seed yields and stem length, and between seed yields and 100 grain weight, on every sowing plot. 3. Relations between varietal yields and the sowing dates are shown in Table 3. Our leading varieties such as Ulsan, Sangdoo, Changdan Backmok, Iksan, Haman, Barchongdeo, and Anion Daerip, which belong to the maturity groups of IV, V, and VI, have been significantly high in yield at each sowing date plot, but the extreme early varieties, that frequently are damaged by insects, moisture and diseases, and the extreme late varieties, that frequently are caught by frost suffering reduced yield, are showed a lower yield than the others. However, extreme early varieties, for instance, Black Hawk, an American variety, and Chung Buk Baek, a Korean early variety, showed high productivity on the late sowing, June and July sowing plots, and Do san No. 6, which is late Japanese variety, showed a high yield on the extreme early sowing, i.e. April sowing plots. 4. Relations between seed yields and the sowing dates on the varietal bases are shown in Table 4. It was observed that, the early varieties did not differ much in yields at the various sowing dates while the yields of late varieties decreased progressively with subsequent dates. However, the extreme late varieties, such as Tamanishiki, that frequently are caught by frost suffering reduced yield, may be difficult to harvest at this location. The results in these experiments showed that in most cases maximum yields were obtained when leading varieties, which are medium or late varieties, were shown in Mid-May, and progressively lower yields were produced from June and July sowings. On the other hand, the late sowings of the early varieties, such as Black Hawk and Chung Buk Baek, in these experiments showed favorable yields compared with the others. From these results, we can predict that our local medium or late varieties produce higher yields at this location than was produced by early varieties in most of the sowing dates, especially the May sowing, and early varieties such as Black Hawk and Chung Buk Baek should be used in the late sowing, June sowing time.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2001.11b
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• pp.49-61
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• 2001

This study was carried out to determine the effect of various fertilizer levels, sowing time and planting density on the growth and yield of Scuteliaria baicalensis GEORGE cultivated after the barley in the southern coastal areas of Korea under the non- mulching condition by direct sowing culture. The flowering date of medium dressing plot(N : P$_2$O$\sub$5/ : K$_2$O=9 : 13.5 : 9kg/10a) and heavy dression plot(N : P$_2$O$\sub$5/, : K$_2$O=12 :18 : 12kg/10a) were July 23. The flowering date of the medium and the heavy dressing plot was delayed by 3days compared with that of non-fertilizing plot. The growth characteristics such as stem length, diameter of main stem, number of branch per plant, main root length, main root length, main root thickness and dry weight of stem leaves were more increased at medium dressing plot than that of other fertilizer levels, The root dry weight of in Scutellaria baicalensis GEORGE cultivated after barley was hlghest at the fertilizing plot of N : P$_2$O$\sub$5/ : K$_2$O=9 : 13.5 : 9kg/10a. The dried-root yield was 178kg in medium dressing plot, 167kg in standard dressing pot, and 126kg in non-dressing plot, The dried-root yield of medium dressing plot was 7% and 41 cie higher than that of standard dressing pot and non-dressing control plot, respectively. Emergence and flowering dates in the sowing time of June 1 were earlier than those of the other sowing times. In the sowing time of June 1, length and diameter of main stem, number of node per main stem, number of branch per plant and dry weight of stem leaves were greater than those of sowing times of June 10 and June 20. Yield components such as main stem length and diameter, main stem numbers, branches per plant, dry weight of stem leaves, main root length and thickness, number of large root and fine root per plant, and dry weight of root were the highest at the sewing time of June 1 as the yield of 71.3kg/10a. Optimum sowing time of Scuteilaria baicaiensis GEORGE cultivated after barley was June 1 in southern areas of Korea. Stem length was long in dense planting of 20${\times}$10cm and short in spacious planting of 30${\times}$10cm and 40${\times}$10cm by direct sowing cultivated after barley. Stem diameter was thick in spacious planting of 30${\times}$10cm and 40${\times}$10cm and was thin in dense planting of 20${\times}$10cm by direct sowing cultivated after barley. Length and dry weight of root per plant were decreased in dense planting of 20${\times}$10cm and were increased in spacious planting of 30${\times}$10cm and 40${\times}$10cm by direct sowing cultivated after barley. Yield of dry root was highest in optimum planting density(30${\times}$10cm 33 plants/㎡) by direct sowing cultivated after barley. The correlation coefficient between number of planting plant and stem length showed highly positive correlation. These characters of stem diameter, number of branches, main root length and yield of dry root mentioned above showed negative correlations with planting plants.