• Korean journal of applied entomology
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• v.25 no.1 s.66
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• pp.21-25
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• 1986

Number of small brown planthoppers, Laodelphax striatellus(F.) negatively correlated with the mean temperature of March in Korea. The low temperature of March delayed the barley growth, heading date, and maturity. Thereby, was small brown planthopper was given a good condition to feed barley, and caused abundant occurence in 1984. In addition, it was possible to predict the occurence ot small brown planthopper by quadractice equations.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.29 no.2
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• pp.114-117
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• 1984

To investigate a possibility of screening for the drought resistance of rice varieties in the slope-ridges, this experiment was conducted in Youngnam Crop Experiment Station in 1982. Seeds were vertically seeded on the slope-ridges which has 30 degree slopes from water level at the front to 1 meter height at the back side. A significant positive correlation was observed between the height of slope-ridges and the PF values (Y=2.25 +0.007 X, r =0.990${\ast}\;{\ast}$).The heading date delayed, the culm length was shortened and the yield was decreased in accordance with the height of slope-ridges. Based upon the above results, it was possible to read the drought resistance of the rice varieties tested. Samnambyeo, Milyang 26, Jinjubyeo and Nongrimna 1 were classified as the resistant ones, while Knob 361-1-8-6-149 was susceptible one.

• Korean Journal of Agricultural Science
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• v.50 no.3
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• pp.365-371
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• 2023

This experiment was carried out to breed a medium maturing variety of Italian ryegrass (Lolium multiflorum Lam.) in Grassland and Forage Crops Division, National Institute of Animal Science, Rural Development Administration (RDA), Cheonan from 2019 to 2020. An Italian ryegrass variety, IR 604 is a tetraploid variety with green in leaf color and has half-erect growth habit in late autumn and erect growth habit in early spring, IR 604 was on May 17 in heading date as a medium maturing variety. Also, IR 604 was longer by 11 cm in flag leaf length and longer by 1.3 cm in plant height than those of the control variety, Kowinner, respectively. IR 604 was also thicker by 1.0 mm in stem thickness and strong in winter hardness. Dry matter (DM) yield (11,036 kg/ha) of IR 604 was 16.6% higher than that of Kowinner. Total digestible nutrient (TDN), crude protein (CP) and relative feed value (RFV) of IR 604 were 60.4, 13.8% and 100.6 which are 1.4, 3.3%, 7.7 higher than those of Kowinner, respectively. Acid detergent fiber (ADF) and neutral detergent fiber (NDF) of IR 604 were 35.5 and 56.7% which are 1.3 and 3.6% lower than those of Kowinner, respectively.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.56 no.2
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• pp.134-139
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• 2011

This study was conducted to evaluate the weed suppressing effects of two winter cover crops, hairy vetch and rye in foxtail millet and sorghum fields in 2010. Crop growth and development and weed occurrences in the fields were examined to know the efficiency of proposed cropping system. In hairy vetch treated plots, heading of minor cereals occurred early. The heading date was earlier by 1 day and 2 days in sorghum and foxtail millet, respectively. However, rye treatment delayed heading by 12 days and 8 days in sorghum and foxtail millet, respectively. Besides he effect of cover crop on ear emergence of crops, the Besides changed growth-related characteristics. Plant height, chlorophyll content and chlorophyll fluorescence of sorghum ere increased in hairy vetch treatment by 46.4% 88.7% and 7.9%, respectively. In foxtail millet, the characteristics ere also increased by 45.6%, 50.9% and 37.8%, respectively, s compared to control. Yields of sorghum and foxtail millet were increased by 105.1% and 135% as compared o control by hairy vetch treatment, respectively. However, he yields of cereal crops were decreased by rye cover crop treatment, the yields of sorghum and foxtail millet were decreased by 25.8% and 119.1%, respectively. Rye cover crop treatment inhibited crop growth suggesting nitrogen starvation in rye treated plots. In rye treatment, plant height, chlorophyll contents and chlorophyll fluorescence of sorghum ere slightly decreased by 7.1%, 10.8% and 10.8%, respectively, as compared to control whereas the inhibitory effects were greater in foxtail millet. Weed occurrences based n weed number in hairy vetch and rye plots were reduced n weed number in hairy vetch and rye plots were reduced y 27% and 20%, respectively. The smothering effect was weakened or disappeared after heading of crops. Weed number and dry weight in hairy vetch plot were increased by 159% and 55.2%, respectively, as compared to control. The results implied that weed suppressing of cover crops could be reduced drastically after heading of crops.

• Journal of The Korean Society of Grassland and Forage Science
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• v.42 no.1
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• pp.26-31
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• 2022

This study was carried out to evaluate the growth characteristics and forage yield potential for warm season grass as emergency forages. The experimental design was a randomized block design (RBD) with three replications. Two barnyard millet (Echinochloa species cv. Shirohie and Jeju native), a pearl millet (Pennisetum glaucum cv Feed milk 2) a proso millet (Panicum miliaceum cv Native), a teffgrass (Eragrostis tef cv. Tiffany) and a kleingrass (Panicum coloratum cv. Selection 75) were compared for forage production and quality at the Mid regions of Korea. Warm season forage crops were sown on May 21 and June 23 respectively, and in 2021, it was sown twice on May 21 and June 21 The number of days to seedling emergence for barnyard millet and teffgrass was observed approximately 10 and 3 days after seeding, respectively. The cultivation period from seeding to harvest was within 60 days for all entry spices except for the late-heading type barnyard millet (within 84 days). As for the dry matter yield by seeding date, the dry matter yield of the late-heading type barnyard millet in May seeding was the highest at 23,872 kg/ha, and the kleingrass was the lowest at 3,888 kg/ha. For the June seeding, the dry matter yield of the late-heading type barnyard millet was 17,032 kg/ha, the highest, and the proso millet, teffgrass and kleingrass showed the lowest at 5,468, 5,442, and 5,197 kg/ha, respectively. The crude protein (CP) content was varied by warm season grass species, but the early-heading type barnyard millet, teffgrass, and kleingrass showed the highest tendency, and the late-heading type barnyard millet showed the lowest at 5.7~5.9%. Neutral detergent fiber (NDF) and acid detergent fiber (ADF) content did not show a significant difference between the seeding in May, but kleingrass in June sowed lower than the others.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.67 no.3
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• pp.180-188
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• 2022

This study was conducted to determine the optimal sowing date for seed yield of summer oat (Avena sativa L.) cultivars "Darkhorse (DH)" and "Highspeed (HS)" in Wanju, Jeonbuk province between 2017 and 2018. We investigated seed yield from 4 sowing dates: July 15, July 30, August 15, and August 30. We evaluated the agronomic characteristics of summer oats (DH and HS). We found the heading date of all cultivars to be within 50 days. Delayed sowing resulted in significantly increased plant height for both years and cultivars. There was no significant difference in spike length of DH and HS which ranged from 12.8 to 17.8 cm. The sowing date of July 30 produced a higher number of grains per spike, but this yield differed significantly by year and cultivars. In 2017, the first sowing resulted in the lowest DH yield at 132 kg per 10a, while the second sowing had the highest yield at 227 kg. HS yield was the lowest in the first sowing at 126 kg and the highest in the third sowing at 219 kg. In 2018, DH had the lowest yield from the first sowing at 184 kg per 10a, and the highest from the second sowing at 240 kg, but there was no significant difference between these yields. The first sowing for HS gave the lowest yield at 160 kg, and the second sowing produced the highest at 258 kg. The germination rate of harvested seeds from each sowing date in 2017 and 2018 was found to be higher than 85% and there was no significant difference between the two cultivars in the 2018 germination rate test. Thus, we found the optimal sowing date for summer cultivation of oats for the highest seed yield to be between July 30 (second sowing) and August 15 (third sowing).

• Journal of The Korean Society of Grassland and Forage Science
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• v.26 no.2
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• pp.91-96
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• 2006

This experiment was carried out in order to examine the winterhardiness, heading date, fresh and dry matter yeild of Festulolium braunii, a hybrid of Festuca pratensis and Lolium multiflum, which is newly introduced in Korea. This experiment was performed at National Livestock Research Institute in Suwon and Namwon from September 2004 to July 2005. The results are as follows. 'Fleurial', 'Boxer', and 'Perun' showed stronger winterhardiness than 'Hwasan 101', which is one of the strongest in the winterhardiness hybrids. Therefore, we do not see there is any problem in winterhardiness when these hybrids are cultivated in Korea. The hybrids are turned out to be mid and late maturing hybrid. The average heading dates of the three hybrids were May 25 in Namwon and May 27 in Suwon. These dates are lower($1{\sim}3$ days) than that of Hwasan 101. They showed $91{\sim}96cm$ in leaf length at 1st cutting times which are comparatively long. This experiment also disclosed that their lodging and regrowth are strong and excellent. We also found out that there are significant difference between regions and hybrids in the total fresh yield per ha. The average fresh yield of Suwon was 83,222 kg/ha and that of Namwon was 69,139 kg/ha. We could not see any difference in the dry matter yield affected by region, however, there were significant difference in hybrids(p<0.05). The crude protein contents of the three hybrids indicated very high figures. the crude protein cotents of Perun, Fleurial and Boxer are 18.0% 17.4% and 16.7% respectively. However the ADF (Acid Detergent Fiber) shows $28.1{\sim}29.2%$ which is less contents than 33.2% of Hwasan 101. We found out from this experiment that these three hybrids have excellent feed quality because the NDF (Neutral Detergent Fiber) is decreased by $7{\sim}3.8%$ comparing that the NDF of Hwasan 101 is 58.3%. Also each hybrids contains more crude fat by 1%, a little more chemical composition and less ash contents. Thus we can tern that chemical composition contents of these hybrids are also fittable.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.32 no.3
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• pp.341-346
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• 1987

Seven barley varieties were tested under three different vernalization durations for observing the effects of vernalization duration and different growth habit on shoot apex development and heading date. The final leaf number per main stem in 3 and 6 weeks vernalized seedlings did not vary among varieties, but ranged 7 to 14 leaves in non-vernalized seedlings. The winter types had more leaves than the spring types. Days for each leaf emergence in non-vernalization were retarded 1. 3 to 1. 5 days in comparison with 3 or 6 weeks vernalized seedlings. In general, the leaf emergence speed of spring types was faster than that of winter types. The VI stage whose double ridge formed, did not vary in 6 weeks vernalization, but spring (Gangbori & Dongbori 2) and facultative or winter types showed two conspicuous difference patterns. The differences of days to X stage were great among different vernalization duration and varieties; the stage of spring types was reached faster than that of winter types. The early varieties within the same growth habit were reached to X stage faster, and the time of flag leaf emergence showed the similar tendency to the differentiation of X stage. The time of the first rapid stem internode elongation became late as for incompletely vernalized seedlings. The time within the same vernalization duration became later in winter types than in spring types, and even within the same growth habit, the time of early varieties became faster than that of late varieties. The growth habit in especially non-vernalized seedlings had highly significant correlation coefficients with the times of leaf development speed, leaf number per main stem, the first rapid stem internode and young spike elongations, X stage, and flag leaf emergence. However, the relationship between growth habit and time of heading in the field was not close.

• Korean Journal of Soil Science and Fertilizer
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• v.22 no.1
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• pp.53-60
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• 1989

The results of the investigation on the effects of plant nutrio-physiological status and reemergence of sudden wilting in rice on the occurrence of sudden wilting were summarized as follows: 1. The occurrence of sudden wilting, degree of damage and occurring time in the investigated variety showed to concur with the results of the previous experiment. 2. Nitrogen and Potassium contents in leaves related an occurrence of sudden wilting at heading stage have a very high negative co-relation (the value is -0.9224 at Yushin and -0.8243 at Milyang 23). 3. Regarding the relation between occurrence of sudden wilting and root activity capacity at the late growth stage, the root activity capacity at productive growth stage showed higher than at reproductive growth stage, which is the same in the two varieties but Milyang 23 is higher than Yushin. It is confirmed that root activity capacity in the two varieties has become very low at reproductive growth stage. 4. The toot activity capacity in the field with potassium showed a small occurrence of sudden wilting and the root activity capacity in the field with no potassium showed a very high co-relation value (the value is 0.8947 at Yushin and 0.7301 at Milyang 23). 5. Regarding the relation between the occurrence of sudden wilting and water evaporation quantity, water evaporation quantity after the heading date has a more direct relation to sudden wilting than that which occurrs prior to the heading date. Water evaporation quantity is higher in the field with no potassium, low leaves and Yushin, than in the field with potassium high leaves and Milyang 23. 6. The starch content in culm of Yushin and Milyang 23 at ripening stage showed high value in proportion to potassium quantity, and the starch content is lower as internode is lower. However, in fourth internode, the starch content is greatly increased in the field with potassium contrasted to the field with no potassium.

• Journal of Climate Change Research
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• v.1 no.2
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• pp.121-131
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• 2010

This study was carried out to evaluate spatial variations in rice production areas by simulating rice growth and yield with CERES-Rice growth model under GCM $2{\times}CO_2$ climate change scenarios. A modified window version(v4.0) of CERES-Rice was used to simulate the growth and development of three varieties, representing early, medium, and late maturity classes. Simulated growth and yield data of the three cultivars under the climate for 1971 to 2000 was set as a reference. Compared with the current normal(1971 to 2000), heading period from transplanting to heading date decreased by 7~8 days for the climate in $2^{\circ}C$ increase over normal, and 16~18 days for the climate in UKMO with all maturity classes, while change of ripening period from heading to harvesting date was different with maturity classes. That is, physical maturity was shortened by 1~3 days for early maturity class and 14~18 days for late maturity class under different climate change scenarios. Rice yield was in general reduced by 4.5%, 8.2%, 9.9%, and 14.9% under the climate in $2^{\circ}C$, $3^{\circ}C$, $4^{\circ}C$, and about $5^{\circ}C$ increase, respectively. The yield reduction was due to increased high temperature-induced spikelet sterility and decreased growth period. The results show that predicted climate changes are expected to bring negative effects in rice production in Korea. So, it is required for introduction of new agricultural technologies to adapt to climate change, which are, for example, developing new cultivars, alternations of planting dates and management practices, and introducing irrigation systems, etc.