• KOREAN JOURNAL OF CROP SCIENCE
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• v.29 no.4
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• pp.394-400
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• 1984

In order to find out the possibility of increasing the number of spikelets by changing transplanting date, this study was conducted at Suwon, Yuseong and Jinju in 1979 and 1980. Climatic consumption effect was different depending on location, year, and variety. Number of spikelets can be increased by changing transplanting date due to the decrease of climatic consumption index (C C I) during the reproductive stage. Transplanting date for higher yield and number of spikelets of Tongil was May 25 at Suwon, from May 25 to June 5 at Yuseong and June 5 at Jinju, and in the japonica, it was slightly earlier than that of Tongil in each location. Increasing the number of spikelets and grain yield by the effect of decrease in C C C during the reproductive stage should be considered the percentage of ripened grains.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.52 no.1
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• pp.17-28
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• 2007

To understand the spring freezing injury symptoms during sensitive growth stage and yield loss of barley and wheat, field tests were done by using vinyl mulching and natural cold weather. The growth stage sensitive were booting, spikelet differentiation and flower organ development stages for both crops. However, barley and wheat differed in their growth responses, in that barley was less affected than wheat. For instance, barley recorded 28 percent dead ears, 10 percent dead plants and 18 percent ear degenerations while wheat recorded higher values of 59 percent, 44 percent and 44 percent, respectively. Although there were no recorded froze-resistant varieties in both barley and wheat, some showed tolerance as their yields were not affected by freezing stress. The 'Chalbori' cultivars of barley and 'Geurumil' and 'Chokwang' cultivars of wheat recorded steady yields. The yield components of barley and wheat that were greatly affected by freezing stress were the number of spike per square and the number of grain per spike. The major cause of yield loss in Suwon 259 and Kangbori was the number of spike per square but not the number of grain per spike. The study showed, however, that both the number of spike per square and the number of grain per spike were vulnerable to freezing and that which contribute much to yield loss of barley and wheat.

• Research in Plant Disease
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• v.17 no.2
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• pp.155-160
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• 2011

To develop the efficient screening methods for antifungal compound active to Chinese cabbage clubroot caused by Plasmodiophora brassicae, the control efficacy of three fungicides fluazinam, ethaboxam, and cyazofamid on the disease was tested under several conditions such as soil types, cultivars of Chinese cabbage, growth stages of the host, and inoculum concentrations. The in vivo antifungal activities of the fungicides on clubroot of two Chinese cabbage cultivars were hardly different. At 7- and 14-day-old seedlings, the fungicides were more effective to control of clubroot than at 21-day-old seedlings. In a commercial horticulture media soil (CNS), disease severity of untreated controls was higher and control activity of the fungicides was less than in a mixture of CNS and upland soil (1:1, v/v). Disease development of the seedlings inoculated with P. brassicae at $1.8{\times}10^7$ spores/pot to $1.1{\times}10^9$ spores/pot was almost same, but control efficacy of the fungicides was negatively correlated with inoculum dosages. To effectively select in vivo antifungal compound on Chinese cabbage clubroot, 14-day-old seedlings need to be inoculated with P. brassicae by drenching the spore suspension to give $1{\times}10^8$ spores/pot 1 day after chemical treatment. To develop clubroot, the inoculated plants are incubated in a growth chamber at $20^{\circ}C$ for 2 days, and then cultivated in a greenhouse ($20{\pm}5^{\circ}$) for four weeks.

• Research in Plant Disease
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• v.15 no.3
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• pp.217-221
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• 2009

Fludioxonil is derived from the antifungal compound pyrrolnitrin produced by Pseudomonas pyrrocinia and classified as a reduced-risk fungicide by the US EPA. The efficacy of fludioxonil for the control of lettuce gray mold caused by Botrytis cinerea was evaluated under several conditions such as growth stages of host, inoculum concentrations, and amounts of potato dextrose broth (PDB) included in spore suspension of B. cinerea. At 4-leaf stage of lettuce plants, fludioxonil applied at 2 ${\mu}g$/ml was more effective for the control of gray mold than at 5- and 6-leaf stages. However, fludioxonil at more than 10 ${\mu}g$/ml provided similar control activity in all growth stages of lettuce tested. The fungicide (10 and 50 ${\mu}g$/ml) also gave excellent control of gray mold on lettuce seedlings inoculated with spore suspensions of B. cinerea ($2.5{\times}10^5$ to $2{\times}10^6$ spores/ml). But, control efficacy of fludioxonil (2 ${\mu}g$/ml) was negatively correlated with inoculum concentration. Addition of PDB in spore suspension of B. cinerea resulted in higher disease severity than non-treated control. By inoculating spore suspension including 0.5% PDB, the fungicide gave the most control activity on the disease, followed by 1% and 2% PDB. The results suggest that fludioxonil has potential to control gray mold of lettuce, but the fungicide at a concentration having moderate activity may represent low control efficacy on the disease under some conditions.

• Journal of The Korean Society of Grassland and Forage Science
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• v.41 no.1
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• pp.41-46
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• 2021

Sorghum×sudangrass hybrid (Sorghum bicolor (L.) Moench, SSH) is one of the most important summer forage crop and it is widely used for silage in Korea. Agriculture is highly dependent on the climate condition and experiencing significant loss of productivity due to climate change. This study was conducted to investigate the correlation analysis between productivity of forage SSH and climatic factors in Central Northern region of South Korea for 3 years (2017 to 2019). Plant height and dry matter yield of SSH were significantly higher in Gyeonggi-do than Ganwon-do. The productivity of SSH is more closely related with temperature than other climatic factors. Maximum temperature and Growing degree days in May and June showed a positive correlation. However, correlation between production of SSH and precipitation was not clear in this study, but rainy days showed a negative correlation (0.42). In conclusion, temperature is most important climatic factor to the maintenance of plant yield.

• Korean Journal of Soil Science and Fertilizer
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• v.1 no.1
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• pp.81-87
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• 1968

It has been made clear that there exist a definite rhythm in the accumulative process of carbohydrates of soybeans, and that there is a great variation in nitrogen metabolism. In spite of earlier or later manuring, it is possible to make use of the above stated conclusion. But in the case of later manuring, there is so short a time of growth before harvest, resulting in the lack of normal growth and in a great effect upon harvest. In the general terms, the first half period of growth may be called that of nitrogen assimilation, and the late half, that of carbohydrate assimilation. It has delayed comparatively distinction between these periods whether manuring was done earlier or later. In other words, the lack of carbohydrates in the first half period of growth has been found to deter the process of protein synthesis. And the lack of protein in a body in the latter half period of growth has been found to weaken photosynthesis that should be active, resulting in the decrease of harvest. Consequently, lack of protein in the body during the period of pod adhesion definitely brought about lack of growth in the latter period of growth. It follows, therefore, that in order to increase harvest, it is necessary to manure comparatively in the early period, and that contents of various forms of nitrogen.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.3
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• pp.216-220
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• 2002

This study was conducted to know the change pattern of chemical components, especially proximate constituents, saponin and free sugars in roots of 4-year ginseng according to different harvesting time, and to find out the optimum harvesting time on the basis of chemical components in fourth year ginseng root. The crude protein content was 20.77% of the highest on the April (shootinzg stage),13.13% of the lowest on the June among all growing stages, and was constant at 17% after the August. But crude oil and fiber contents showed the highest value on the May (flowering stage). The content of total sugars which was the largest constituent among the chemical components in ginseng root was in the range of 60~7(1% during the all growing stages. It showed the highest value of 7l% on the June, but the lowest of 60% on the May. The total free sugar contents was the highest on the April (20.40%), but the lowest on the May (11.89%). The change pattern of sucrose contents (10.96-19.60%) was same as the total sugars contents (11.89-20.40%), on the other hand, the contents of glucose and maltose were not changed significantly during all harvesting times. The contents of crude saponins and total ginsenosides had the value of 7.60% and 4.09% on the May, respectively. That was statistically significant, but the other harvesting times were not. Therefore, on the basis of the only chemical characteristics in the four year-old ginseng root, we suggest that the harvesting on the May at flowering stage was most proper time.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.57 no.3
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• pp.310-315
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• 2012

The vegetable perilla is proved to be a late-maturing plant that flowers at the early of Oct. regardless of sowing time, so that the sowing time for seed production should be decided under consideration of maturity before beginning of frost. This experiment was carried out to determine the sowing date for seed production at greenhouse on late-maturing perilla cultivar, 'Ipdlkkae 1' in the middle region of Korea. The sowing dates were 8 times from May 6 to July 15 with an intervals of 10 days. As sowing date was delayed, the stem height, no. of nodes, no. of branches, no. of cluster per plant and no. of capsules per cluster were decreased. But as sowing was early, the lodging was occurred because of heavier growing. Days to flowering was linearly decreased about 0.86 day as affected by a day's delayed. But days from flowering to maturing was not significantly affected by sowing date. The grain yield was not significantly different among sowing from May 6 to June 15 and rapidly decreased the sowing after June 25 because of the reductions of no. of cluster and percent of ripened grain. Considering accumulative temperature, lodging, germination rate and grain yield, it is suggested that the sowing for seed production in late-maturing perilla cultivar should be finish before June 15 (transplanted at July 15) at greenhouse in the middle region of Korea.

• Korean Journal of Plant Resources
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• v.24 no.2
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• pp.189-194
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• 2011

This study was performed to evaluate the effect of pinching time on growth and quality of Glycyrrhiza uralensis soil cultured in Chungbuk Agricultural Research and Extension Service from 2008 to 2009. The treated pinching time were given as the June 30, July 30, August 30, and non-pinching (control). The amounts of pinching were 20% of stem length each plant. The obtained results from this study were summarized as follows; The plant height and number of branches were higher in control than pinching treatments. The stem and leaf weight were increase with early pinching. The plant height and stem diameter were not affected by pinching time. There was no regular trends in runner growth. We found that pinching was induced root growth, and early pinching was accelerated root growth. The root yield was increased in JUN and JUL pinching treatments as 11-30% in 2 years plants and 6-11% in 3 years plants compared to control as 238 kg/10a and 432 kg/10a, respectively.

• Journal of Bio-Environment Control
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• v.13 no.1
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• pp.21-25
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• 2004

This experiment was carried out to investigate the effect of apex removal at different leaf ages on the growth and yield of broccoli in pinching cultivation. Apex was pinched when 2, 3 or 4 true leaves were spread during nursery bed, and non-pinching was conventional method. The plant height was not different among treatments but the fresh weight was decreased as the pinching days were delayed. The numbers of leaves and lateral shoots were increased compared to those of non-pinching by pinching. Days to central budding were shortended by 3 days when pinched at 2 true leaves spreading stage than those of non-pinching. Central (1st) head weight was heaviest when pinched at the time of 2 true leaves spreading (157g). Total head weight was heaviest when pinched at the time of 2 true leaves spreading (378g), and lowest at 4 true leaves spreading stage (196g). Marketable yields were increased by 48% when pinched at the time of 2 true leaves spreading (1,754kg) as compared with those of non-pinching (1,184kg) and lowest when pinched at the time of 4 true leaves spreading (820kg). Also, first harvest was shortended by 6 days by pinching at 2 true leaves spreading stage.