• Korean Journal of Soil Science and Fertilizer
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• v.41 no.3
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• pp.158-163
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• 2008

This study was carried out to elucidate the relationship between yields and inorganic nutrient contents, and then establish of critical range of inorganic nutrient contents in leaves of watermelon in protected cultivation in Gochang from 2004 to 2006. In considering the yields and nutrient contents of watermelon, the critical ranges of macro-nutrient contents in leaves of watermelon at 20 days after transplanting were in N 5.0~6.6%, P 0.30~0.57%, K 3.5~4.2%, Ca 1.7~3.8% and Mg 0.20~0.42%, respectively. The critical ranges of micronutrient content, such as Fe, Mn, Zn, Cu and B, were not found the regular trend with different growth stages. However, the critical range of micronutrient contents in leaves of watermelon at 20 day after transplanting were in Fe 96~128, Mn 67~201, Zn 40~60, Cu 6~9 및 B $41{\sim}82mg\;kg^{-1}$, respectively. Finally, these results might be used at the indicator for critical nutrient contents for diagnosis of nutritional disorder in watermelon in protected cultivation.

• Korean Journal of Soil Science and Fertilizer
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• v.40 no.6
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• pp.471-475
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• 2007

This study was carried out to elucidate the relationship between yields and inorganic nutrient contents, and then establish of critical range of inorganic nutrient contents in leaves of net melon in protected cultivation in Naju from 2004 to 2006. In considering the yields and nutrient contents of net melon, the critical ranges of macro-nutrient contents in leaves of net melon at 25 days after transplanting were in N 3.4~4.8%, P 0.4~0.7%, K 3.4~5.1%, Ca 2.7~4.1% and Mg 0.6~0.8%, respectably. The critical ranges of micronutrient content, such as Fe, Mn, Zn, Cu and B, were not found the regular trend with different growth stages. However, the critical range of micronutrient contents in leaves of net melon at 25 days after transplanting were in Fe 102~164, Mn 52~116, Zn 28~98, Cu 7~15 and B $36{\sim}72mg\;kg^{-1}$, respectably. Finally, these results might be used at the indicator for critical nutrient contents for diagnosis of nutritional disorder in net melon in protected cultivation.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.57 no.3
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• pp.248-253
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• 2012

Demand is increasing for new functional and health food such as natually colored or flavored rices. Shinongheugchal, Shinmyeongheugchal, colored glutinous rice, were breed as new variety in Jeollabuk-do ARES. Shinongheugchal and Shinmyeongheugchal are medium to late maturing cultivars and higher than Heugnambyeo in term of C3G content. It was conducted to improve the quality of Shinongheugchal, Shinmyeongheugchal in different cultivation regions, transplanting time. The cultivation regions was Jinan (mid-mountainous area) and Iksan (plain area). Transplanting time was May. 20, May. 25 May 30 and Jun. 5 in Jinan, that of Iksan was Jun. 5, Jun. 10, Jun. 15 and Jun. 20. The average heading date of Shinongheugchal and Shinmyeongheugchal was Aug. 13, Aug. 19 and Aug. 15, Aug. 22 in Jinan and Iksan. The average yield of Shinongheugchal(brown rice) in Jinan was 514 $kg\;10a^{-1}$ and that of in Iksan was 529 $kg\;10a^{-1}$. The average yield of Shinmyeongheugchal(brown rice) in Jinan was 508 $kg\;10a^{-1}$ and that of in Iksan was 511 $kg\;10a^{-1}$. The average C3G content of Shinongheugchal in Jinan was 273.9 mg/100g, that of in Iksan was 228.2 mg/100g. The average C3G content of Shinmyeongheugchal in Jinan was 126.3 mg/100g, that of in Iksan was 101 mg/100g. The optimal transplanting date was May 30 in Jinan and June 10 in Iksan considering the yield and C3G content in Shinongheugchal. The optimal harvesting date of Shinongheugchal in Iksan was 50 days after heading.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.66 no.4
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• pp.419-427
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• 2021

In South Korea, direct seeding of rapeseed (Brassica napus L.) is difficult during spring cultivation in early March because of the low yield production associated with late flowering and poor seed quality. To compare the period of direct sowing, the present study investigated the growth characteristics of rapeseed according to planting dates. Specifically, 35 day-old seedlings were transplanted or directly sown on four different dates (late February, early March, late March, and early April) in 2020 and 2021. As the planting date was delayed, the days to flowering of rapeseed decreased. Similarly, the plant height, seed set percentage, and seed yield of rapeseed were reduced upon delay in planting. The seed yield of rapeseed through direct seeding in late February was the highest, 2.76 ton·ha^-1. On all seeding dates, except for late February, the transplanted rapeseed produced a higher yields than the directly seeded rapeseed. The crude oil and oleic acid content, which is related to the quality of rapeseed, decreased with the delay in planting dates, and this decrease was greater, with the direct seeding of rapeseed depending on the sowing time. In the correlation analysis, the planting date was significantly and negatively correlated with the yield, crude oil content, and oleic acid content of the transplanted rapeseed, while the sowing date was negatively correlated with the plant height, silique size, yield, and seed quality of the directly seeded rapeseed. Finally, the effect of planting date on rapeseed growth was stronger in direct seeding than in transplanting. Therefore, during spring cultivation after late February to early March, transplanting, rather than direct seeding, in more advantageous in terms of seed quality and yield.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.61 no.4
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• pp.251-256
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• 2016

The increase in carbon stock and sustainability of crop production are the main challenges in agricultural fields relevant to climate change. Methane is the most important greenhouse gas emitted from paddy fields. This study was conducted to investigate the effects of tillage and cultivation methods on methane emissions in rice production in 2014 and 2015. Different combinations of tillage and cultivation were implemented, including conventional tillage-transplanting (T-T), tillage-wet hill seeding (T-W), minimum tillage-dry seeding (MT-D), and no-tillage-dry seeding (NT-D). The amount of methane emitted was the highest in T-T treatment. In MT-D and NT-D treatments, methane emissions were significantly decreased by 77%, compared with that in T-T treatment. Conversely, the soil total carbon (STC) content was higher in MT-D and NT-D plots than in tillage plots. In both years, methane emissions were highly correlated with the dry weight of rice ($R^2=0.62{\sim}0.96$), although the cumulative emissions during the rice growing period was higher in 2014 than in 2015. T-T treatment showed the highest $R^2$ (0.93) among the four treatments. Rice grain yields did not significantly differ with the tillage and cultivation methods used. These results suggest that NT-D practice in rice production could reduce the methane emissions and increase the STC content without loss in grain yield.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.spc1
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• pp.33-36
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• 2005

In order to find out better cultivation practices in mid-mountainous area to produce high quality rice, an experiment involving four transplanting times and four varieties was carried out, during past three years $(2002\~2004)$. There was no significantly different on palatability of rice between transplanting time, but an interaction effect was between transplanting time and variety, The palatability of milled rice of Sangmibyeo, Hwayongbyeo and Junambyeo transplanted at May 10th were higher than Samcheonbyeo. The palatability of milled rice grown by May 20th day's transplanted, Sangmibyeo and Junambyeo were higher than Samcheonbyeo. The palatability of milled rice grown by May 30th day's trans-planted, Sangmibyeo and Hwayongbyeo were higher than Samcheonbyeo and Junambyeo. And the palatability of milled rice grown by June 9th day's transplanted, Sangmibyeo and Samcheonbyeo were higher than Hwayongbyeo and Junambyeo. It can infer that Sangmibyeo is one of the best option over the transplanting times in term of palatability, Amylose content of milled rice was showed without a significant difference between transplanting time, but there was an interaction effect between transplanting time and variety. The amylose content of grown by May 20th day's transplanted, Sangmibyeo and Samcheonbyeo were lower than Junambyeo. The amylose content of milled rice grown by June 9th day's transplanted, Sangmibyeo and Samcheonbyeo were lower than Hwayongbyeo and Junambyeo. And the amylose content of milled rice grown by May 10th day's and May 30th day's transplanted, was showed without a significant difference between variety. The protein content of milled rice grown by later season transplanted was lower than grown by earlier, The head rice yield wasn't different significantly between the treatment of transplanting times and varieties. But the yield of milled rice grown by transplanted at May 20th day was high most in between the treatment of transplanting time. In a conclusion gathering all above the results, 20th May day's transplanting time and Sangmibyeo was one of the best option for producing high quality rice among the treatments in considering with head rice yield, palatability, amylose${\cdot}$protein content and productivity, at Mid-mountainous area.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.27 no.4
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• pp.439-451
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• 1982

In fact, rice cultivation technique from 1962 to 1970 was very slight, but this technique from 1970 to now was remarkably developed in Korea, it was due to development of high fretilizer responsive and lodging resistant variety, Tongil; ie. Ind. ${\times}$ Japonica remote-cross rice variety. The main factors of this development is as follow: Firstly the most farmer (more than 90%) used newly developed seedling growth method; polyethylene film covered protected nursery bed. Secondly date of transplanting (middle or late part. of May) was earlier 10-15days than before 1970. Thirdly new varieties were highly lodging resistant at high fertilizer level $(N-P_2O_5-K_2O:15-9-11 kg/l0a)$. However, this level is 50% increased one than it for Japonica varieties. At forth planting density increased up to 75-80 hills per $3.3m^2$. Added to these factors, farm labor shortage and wage increase due to economic development gave a chance for introduction of transplanting machine to farmer in 1977. It's use increased for 100, 800 ha in 1981. The most of farmers are using herbicides and weed control system dependoing on wood composition has been established and disseminated to farmer.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2000.11c
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• pp.827-834
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• 2000

A granular herbicide applicator attached to conventional ride-on rice transplanter with 6 rows was developed in order to carry out both transplanting and herbicide application at once. It resulted in labor saving by 98%. The prototype is composed of a metering device and a spinning disc spreader. The application rate per 10a can be varied from 1 to 3 kg and the application swath is 1.8 m, which is the planting width of the ride-on rice transplanter with 6 rows. The angular speed of spinning disc and the application height were used as design factors to obtain the uniform distribution of herbicide granules. As the result of experiment, the distribution uniformity showed a tendency to be proportional to the increases of both spinner angular speed and application height. The prototype with angular speed of spinning disc of 7359 rpm and the application height of 20 cm was made and its distribution uniformity was relatively uniform with the CV(coefficient of variation) of 21.7%. In field test, when the tested herbicides such as ACl40+Stomp and Londax+YRC were applied, the weed control has continued for 65 days since transplanting was done.

• Journal of The Korean Society of Agricultural Engineers
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• v.54 no.2
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• pp.15-26
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• 2012

For stable and sustainable crop production, understanding the effects of climate changes on agricultural water resources is necessary to minimize the negative effects which might occur due to shifting weather conditions. Although various studies have been carried out in Korea concerning changes in evapotranspiration and irrigation water requirement, the findings are still difficult to utilize fordesigning the demand and unit duty of water, which are the design criteria of irrigation systems. In this study, the impact analysis of climate changes on the paddy water demand and unit duty of water was analyzed based on the high resolution climate change scenarios (specifically under the A1B scenario) provided by the Korea Meteorological Administration. The result of the study indicated that average changes in the paddy water demand in eight irrigation districts were estimated as -2.4 % (2025s), -0.2 % (2055s), and 3.2 % (2085s). The unit duty of water was estimated to increase on an average within 2 % during paddy transplanting season and within 5 % during growing season after transplanting. This result could be utilized for irrigation system design, agricultural water resource development, and rice paddy cultivation policy-making in South Korea.

• The Plant Pathology Journal
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• v.18 no.3
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• pp.142-146
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• 2002

The effect of potassium phosphonate ($KH_2PO_3 or $K_2 HPO_3$) on the control of Phytophthora root rot of lettuce was evaluated in a liquid hydroponic culture. Phosphonate 100 ppm strongly inhibited mycelial growth of Phytophthora species in vitro but did not affect normal growth of lettuce in a greenhouse test. Application of the chemical before infection showed over 94% control value, while it was less than 35% when applied after infection. In a field trial, phosphonate 100 ppm, which was directly supplemented into the nutrient solution, satisfactorily controlled the disease as it did not develop until 28 days after transplanting and remained at less than 2% infection rate at the end of cultivation. Meanwhile, in the control plot, the disease initiated at 7 days after transplanting and developed rapidly reaching over 70% infection rate at 28 days. Population density of the causal pathogen, R drechsleri, in a heavily infested farm was 22.0-25.0 cfu/100 ml of nutrient solution. However, it decreased to 1.3-2.0 cfu/100 ml at 7 days after treatment with phosphonate 200 ppm.