• KOREAN JOURNAL OF CROP SCIENCE
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• v.60 no.3
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• pp.343-348
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• 2015

Soybean is one of the important food crop around the world. Especially in East Asia, it is the main ingredient for traditional food like soy sauce and soy paste. The double cropping system including soybean following onion, Chinese cabbage, and potato is widely adopted in Southern region of Korea. In this system, sowing date of second crop (soybean) can be delayed depending on first crops' growth period and weather condition. When planting date is delayed it is known that soybean yield is declined because of shorter vegetative growth period and earlier flowering induced by warm temperature and changes in photoperiod. The objective of this study was to determine soybean growth and yield responses as plant populations at late planting date. Field experiment was conducted at Department of Functional Crop, National Institute of Crop Science, RDA located in Miryang, Gyeongsangnam-Do for two years ('13-'14) in upland field with mid-late maturity cultivar Daewon. A split-plot block design was used with three replications. Main plots were three sowing dates from June 20 to July 20 with 15 days intervals, and subplots were 4 levels of planting densities. Data of maturity (R8) was recorded, yield components and yield were examined after harvesting. Experimental data were analyzed by using PROC GLM, and DMRT were used for mean comparison. Optimum planting population for maximizing soybean yield in late planting which compared with standard population. In mid-June planting, higher planting density causes increased plant height and decreased diameter which lead to higher risk of lodging, however, reduced growth period due to late planting alleviated this problem. Therefore higher seeding rates can provide protection against low seedling emergence caused by late planting in this region.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.3
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• pp.41-48
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• 1965

This study was aimed at knowing the magnitude of year variation in rice heading dates under the different seasonal cultures, and to estimate the heading date in advance. Using six rice varieties such as Kwansan, Suwon＃82, Suwon ＃144, Norin＃17, Yukoo＃132 and Paltal, the early, ordinary and late seasonal cultures had been carried out at Paddy Crop Division, Crop Experiment Station at Suwon for the six-year period 1959 to 1964. In addition the data of the standard rice cultures at the Provincial Offices of Rural Development for the 12-year period 1953 to 1954, were analyzed for the purpose of clarifying a relationship between variation of rice heading dates and some of meteorological data related to the locations and years. The results of this study are as follows: 1. Year variation of rice heading dates was as high as 14 to 21 days in the early seasonal culture and 7 to 14 days in the ordinary seasonal culture, while as low as one to seven days in the late seasonal culture which was the lowest among three cultures. The magnitude of variation depended greatly on variety, cultural season and location. 2. It was found out that there was a close negative correlation between the accumulated average air temperature for 40 days from 31 days after seeding and number of days to heading in the early seasonal culture. Accordingly, it was considered possible to predict the rice heading date through calculation of the accumulated average air temperature for the above period and then the linear regression(Y=a+bx). On the other hand, an estimation of the heading date in the late seasonal culture requires for the further studies. In the ordinary seasonal culture, no significant correlation between the accumulated average air temperature and number of days to heading was obtained in the six-year experiments conducted at Suwon. There was a varietal difference in relationship between the accumulated average air temperature for 70 days from seeding and number of days to heading in the standard cultures at the provincial offices of rural development. Some of varieties showed a significant correlation between two factors while the others didn't show any significant correlation. However, there was no regional difference in this relationship.

• Journal of The Korean Society of Grassland and Forage Science
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• v.36 no.4
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• pp.287-292
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• 2016

The objective of this study was to determine the effect of harvesting time of rice on growth characteristics and dry matter yields of Italian ryegrass (Lolium multiflorum Lam., IRG) 'Kowinearly' after seeding them in paddy field. Experiments were performed in National Institute of Animal Science, RDA (Cheonan, Choongcheongnam-do province of Korea) for four years (2011~2014). Italian ryegrass variety 'Kowinearly' was seeded at experimental paddy fields before rice harvest in late September. Rice were harvested at 10, 20, and 30 days after seeding of IRG. As the harvest time of rice became later, the number of tillering before winter was reduced and IRG plant length before winter was shorter. The dry matter yield of IRG was also reduced. When rice were harvested at 20 days and 30 days after sowing of IRG compared to the rice harvested in autumn at 10 days after sowing of IRG, the number of tillering for IRG before winter was decreased by an average of 19% and 40%, respectively. The winter survival ratio of IRG was decreased by an average of 13% and 19%, respectively. Their dry matter yields were also reduced by an average of 8% and 19%, respectively. The heading date was different from each other in three years. The plant length at the time of IRG harvest in the spring was not significantly different among treatment groups. Taken together, our results suggest that when Italian ryegrass is grown in paddy fields by the method of 'seeding of IRG before rice harvest', rice should be harvested as soon as possible after sowing of IRG 'Kowinearly' in the autumn to increase forage productivity.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.63 no.3
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• pp.186-195
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• 2018

A field study was conducted over a 3-year period from 2014 to 2016 in the central plain area, Suwon, Korea, 1) to compare the biomass production between machine-transplanted and water-broadcast seeded silage rice and 2) to elucidate the growth factors that affect the difference in biomass production between the two cultivation practices. The heading date for the water-broadcast seeded silage rice was September 11-18, which was delayed by 11-17 days when compared to that for the machine-transplanted silage rice. On average, water-broadcast seeded silage rice had a shorter plant height, more panicles per area, and a greater biomass production because of the increased straw dry weight. However, the difference in dry weight of each plant organ between the two cultivation practices exhibited yearly variation. When the data were pooled across experimental years, cultivation practices, and varieties, biomass production was highly positively correlated with straw dry weight but not with panicle dry weight. When the ratio of water-broadcast seeding to machine-transplanting was analyzed, total dry weight and straw dry weight were positively associated with each other, whereas no relationship was found between total dry weight and panicle dry weight. Despite that water-broadcast seeded silage rice produced more panicles per area than machine-transplanted silage rice, the two cultivation practices had a similar dry weight per culm. Therefore, we conclude that the silage rice from the water-broadcast seeding, compared to the machine-transplanting, produced more biomass because of the combination of the increased panicle number per area and a similar dry weight per culm. These results suggest that silage rice could be produced through water-broadcast seeding to increase biomass production with low labor and cost input.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.54 no.2
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• pp.218-224
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• 2009

In organic fanning systems, integration of cover crops into cropping system are recommended to improve the soil quality, to prevent soil erosion, and to provide biological control of weeds. The aim of the present study was to evaluate the optimal seeding dates of major cover crops. To know optimal seeding dates, crimson clover, alfalfa, rye and hairy vetch were sown on 20. Sep., 27. Sep., 4. Oct., 11. Oct., 18. Oct., 25. Oct. Rye could germinate and grow well in all the tested sowing dates. Hence, it was concluded that the sowing of rye could be conducted later in fall or more earlier in spring than any other cover crops tested in this study. Growth and ground covering capacity were significantly decreased by late sowing in alfalfa and crimson clover. For safe overwintering, alfalfa and crimson clover should be sown before late September. Similarly, field emergence of hairy vetch was found to be sensitive to soil temperature, however, its growth and ground covering capacity after overwintering was enough to compensate the delay in sowing. Germination tests in laboratory revealed that hairy vetch grew faster at $25^{\circ}C$ compared to $20^{\circ}C$. The result suggested that germination and growth rate of hairy vetch was rapidly decreased at low temperature. Therefore, it is recommended that hairy vetch should be sown as soon as possible in September for improving stand establishment after overwintering.

• Korean Journal of Medicinal Crop Science
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• v.2 no.2
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• pp.114-120
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• 1994

Experiment was conducted to investigate the effects of planting date and planting methods with seedling size on bolting and yield of Ostericum koreanum (MAX.) KITAGAWA Seeding methods were also reviewed to imvestigate their effects on seedling characteristics. This experiment was carried out in Chuncheon during 1988 growing season. The small seeding rate and broadcasting had higher rates of emergence than the others. There was no big difference in seedling size by seedling rate, and more seedling growth was in drilling methods among seed planting methods. The quantity of seedling were produced with the order of medium, small and lastly large seedling. Dense planting $(8l\;/33m^2)$ was advantageous in producing small seedling. Large seedling had earlier flowering than the others and growth was good in planting small seedling with drilling method. The rates of bolting by seedling sizes were 89.6% in large, 64.6% in medium and 36.9% in small seedling. Bolting was influenced the root Quality by producing lignified root which had a least commercial value. More root growth was shown in unbolting plant compared to bolting plant seedling and broadcasting had much more root growth than seedling from drilling. Fresh root yield of unbolting plant was higher than that of bolting plant and highest yield was obtained in the broadcasting plot with small seedling.

• Korean Journal of Weed Science
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• v.13 no.2
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• pp.114-121
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• 1993

Differences in need occurrence and competition were investigated among five types of rice(Oryza sativa L.) cultivation. Dry weights of weeds in between transplanting and/or seeding and heading date showed in the decreasing order of dry direct-seeded, flood direct-seeded, machine transplanting with 10-day-old seedling, machine transplanting with 30-day-old seedling, and conventional hand transplanting. A similar trend was obtained with application of weedy followed by weed-free. Weed-free periods allowed to decrease by 20% dry weight of rice were 3 weeks after transplanting(WAT) in transplanting cultivations, 5 weeks after seeding(WAS) in wet direct-seeded rice, and 7-8 WAS in dry direct-seeded rice. On the other hand, weedy periods as determined by the same criterion were 9 WAT in conventional hand transplanting and machine transplanting with 30-day-old seedling, 7 WAT in machine transplanting with 10-day-old seedling, 8 WAS in dry direct-seeded rice, and 6 WAS in flood direct-seeded rice.

• Journal of The Korean Society of Grassland and Forage Science
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• v.39 no.1
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• pp.17-23
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• 2019

This experiment was carried out to evaluate the characteristic and productivity of forage corn varieties sown at the last ten days of May at Cheonan of Korea on 2017 and 2018. Forage corn varieties sown on 24th May 2017 and $25^{th}$ May 2018 were emerged in 5th and 1st June, respectively. Silking date of forage corns was different among varieties(p<0.05). Stem length of forage corns was not different among the varieties, except Kwangpyeongok(KPA) and Nero IT. Stem diameter of forage corns was not different amaong the varieties. Outbreak rate of black streaked dwarf virus was lower than 3% in all varieties. Total digestible nutrient(TDN) yield was different among corn varieties(p<0.05), which was higher in P32P75, followed by P2088, P31N27, and KPA. The TDN yield of varieties had direct correlation with stem length, stem diameter and ear yield, respectively(p<0.01). Average of TDN in all varieties was 69.8%. These results suggested that forage corn variety with late-seeding adaptability is more important for increasing the productivity of forage corn If harvesting of winter forage crops have to be finished in the middle ten days of May in middle region of Korea.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.40 no.1
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• pp.59-68
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• 1995

Investigated were the relationships between plumule elongation characteristics and seedling emergence of 46 varieties including native, improved and red rice varieties of Korea, and varieties from U.S.A., Italy, India, Japan under 1, 3, and 5cm deep sowing with irrigated and non-irrigated condition. Experiments were carried out in paddy field of sandy loam. There was heavy shower of 19.2mm on the next day of seeding and thereafter, clear and dry weather continued during the experiment period. Soil temperature averaged over 30 days after seeding was $16.4^{\circ}C$ at 3cm depth. Soil hardness increased linearly up to 2.5kg /$cm^2$ on the 14th day after seeding, on which date irrigated plot was irrigated through furrow, and up to 4kg / $cm^2$ on the 28th day in non-irrigated plot. Soil hardness dropped near to 0kg /$cm^2$ after irrigation and developed up to 2.5kg /$cm^2$ again by 28 days after seeding. Seedling emergence was higher in irrigated plots than non-irrigated plots at all seeding depths. Korean improved varieties were substantially lower in seedling emergence under non-irrigated condition of 1 cm deep sowing than those under irrigated condition. This poor seedling emergence resulted mainly from delayed emergence by exposing them to greater soil strength. Percent seedling emergence under irrigated and non-irrigated condition showed signifi-cant correlations at 3 and 5 cm deep sowing. Korean improved varieties belonged to the group of poor seedling emergence, and I taliconaverneco, Chinsura Boro and Weld Pally to best group under both irrigation conditions at 3 and 5cm deep sowing. Seedling emergence showed highly signifi-cant positive correlation with the plumule length of mesocotyl ＋ 1st internode ＋ incomplete leaf and of mesocotyl＋coleoptile. Among the characters constituting plumule length, incomplete leaf length showed greatest positive correlation followed by coleoptile and mesocotyl under irrigated condition at 3 and 5 cm deep sowing, and highest correlation with mesocotyllength followed by first internode and incomplete leaf under non-irrigated condition. Days to 50% seedling emergence at 1 cm deep sowing with irrigation showed great varietal variation of 10 to 30 days, and showed high significant negative correlations with percent seedling emergence under both irrigation conditions except for 1 cm deep sowing with irrigation, Days to seedling emergence revealed sig-nificant negative correlations with plumule characters except 2nd internode, showing highest cor-relation with incomplete leaf length.

• Journal of The Korean Society of Grassland and Forage Science
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• v.22 no.1
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• pp.1-8
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• 2002

Chufa (Cyperus esculentus L.) belongs to one of the sedge family and pows well in summer. The aboveground part of chufa is mostly consisted of leaves and the underground part is mostly composed of a clump of fibrous root with tuber. At the seeding year, it does not reproductive development but produces a lot of tuber. It produced many tillers from the tuber and grows in clumps as a bunch type. The plant height of mature chufa was 73 to 75cm and it grown fully in the middle of July. The number of tillers were increased rapidly until the end of July and still increased slowly after August but it showed very poor growth. The final fresh weight and dry matter yield of aboveground part of chufa were 40.3 tou/ha and 12.1 tou/ha. respectively. The regrowth of aboveground part was vigorous in the early stage of growth after 1st cutting but it was decreased rapidly after the second cutting. In control plot, the number of tubers per a clump were 722 at final stage and their fresh and drymatter yields per m: were 4.2kg and 1.9kg, respectively. In experimental plots, the amount of tubers was decreased steadily according to delay of cutting date, but late cutting date was not affect the tuber formation severely because the tuber produced already early in August. The nutritive value of chufa in vegetative growth stage was good but it was decreased according to growing up. The contents of crude protein(CP), neutral detergent fiber(NDF), dry matter digestibility (DMD) and total digestible nutrients(TDN) of aboveground part of chufa harvested finally were 6.1%, 51.5%, 39.8%, 33.2% and 39.4％, respectively. The contents of crude protein(CP), neutral detergent fiber(NDF), dry matter digestibility(DMD) and total digestible nutrients(TDN) of tubers of chufa were 6.1%, 81.5%, 39.8%, 33.2% and 39.4%, respectively and the content of oil was as high as 16.2%, especially.