• Korean Journal of Agricultural Science
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• v.42 no.3
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• pp.151-158
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• 2015

This study was conducted to know the variation and relationship of rice grain quality and starch pasting properties by transplanting times. Two early maturing rice cultivars which accounted for the most area of early maturing rice cultivar in Chungnam province were used. The experiment was laid out in a split-plot design with 3 replications. The main plot consisted of three transplanting times viz. early (April 25), ordinary (May 25) and late (June 25) with sub-plots containing two cultivars. According to the transplanting times, most of rice grain quality and starch pasting properties showed significant difference and Joami showed higher grain quality than Unkwang in all transplanting times. Especially, rice grain quality was improved when transplanted late, showing high head rice and glossiness of cooked rice due to the lower mean temperature during grain filling stage. Glossiness of cooked rice was positively correlated with head rice ratio, amylose content and setback value, and negatively correlated with chalky rice ratio and protein content. The highest positive and negative correlation were observed between breakdown value and peak viscosity ($r=0.98^{**}$), and breakdown and setback ($r=-0.94^{**}$), respectively. These results provide some information for rice researchers and producers producing cultivars with an improved quality, suggesting that rice quality is highly influenced by temperature at grain filling stage, and transplanting times is crucial in improving rice quality. In addition, starch pasting properties are useful for determining rice quality because rice grain quality and starch pasting properties are dependent on each other.

• Korean Journal of Agricultural and Forest Meteorology
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• v.2 no.4
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• pp.148-155
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• 2000

The typhoon and flooding injury in rice were investigated both the region of downpour at the middle of August and the region of typhoon 'Yanni' at the late of September, 1998 in Kyongbuk provincial of Korea. More than 10% of rice stem were buried by soil inundation, the heading was delayed and the high node tiller was brought out. Yield components were deteriorated and yield was reduced. As the clay in the muddy water was attached on grains of rice, the yield was greatly reduced by reason of low grain filling ratio and polished rice ratio. The injury of muddy water was less at yellow ripening stage than at early ripening stage. On the other hand, the muddy water injury was reduced by the fungicide 'Benomyl' and 'Daconil' treatments. The degree of lodging according to varieties and ripening stages was not made a great difference, while the lodging was mainly occurred in the early transplanting time. In a week after lodging, viviparous spikes were occurred in almost all varieties, the degree of viviparity was shown highly in order of early maturing, middle maturing and late maturing varieties in the field as well as in laboratory test. The viviperous spikes were greatly occurred in the lodging toward hill space within row than row space because the more grains were touched on the ground.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.36 no.2
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• pp.127-133
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• 1991

Experiments were conducted to investigate the effect of light shading around the heading stage on grain yield and its components of rice. Early, medium, and late-maturing varieties were trected with the light shading of 50% and 75% from the reduction division stage to 20 days after heading date. Heading date were delayed 2-3 days, whereas the mid -late varieties, Sangpung- byeo, and Bongkwang- byeo were no significantly affected. Culm length was increased and panicle exsersion was reduced as the shading treatments become higher, and the degree of the shading effect was more intensive at 75% of shading. The rate of spikllet degeneration was higher at the secondary rachis branches than the primary rachis branch. The early maturing varieties showed the higher rate of spikelet degeneration. Spikelet number was reduced 12-15, spikelet sterility was increased and ripening rate was declined by the shading treatments. Grain yield was decreased by 30-40% at the shading treatment of 50%, and 50% at the shade treatment of 75%.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.31 no.1
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• pp.1-8
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• 1986

This study was investigated about influence of different cold water irrigation on the nutrient uptake of leaf blade, rachis branches and chaff. Longer duration of cold water irrigation increased total nitrogen content in leaf blade, branches and chaff but decreased the content of phosphate, potassium and silicate. The highest content of total nitrogen and phosphate showed at heading stage, that of potassium in leafblades and branches at heading but in chaff at maturing stage, and that of silicate at maturing stage. Inorganic element content in branches was similar with that in chaff in general. The excessive uptake of nitrogen by cold water irrigation caused decrease in the uptake phosphate, potassium and silicate showing clear nutrient disorder in the blades and chaff. High total nitrogen and low silicate in rice plants seemed to lead to degeneration of branches and spikelets, and to spikelet sterility. Degeneration and sterility appeared to be closely related to nutrient status of branches.

• Journal of Aquaculture
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• v.2 no.1
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• pp.21-32
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• 1989

This study was undertaken to understand development stage of ovary and changes of hormone concentrations in the Israeli carp, Cyprinus carpio from Ferbruary to May. The results obtained in these experiments are as follows: 1. Serum LH levels began to increase sharply in March, coinciding with the onset of rapid ovarian development. 2. LH levels were well correlated with changes in gonadosomatic index. 3. Dramatic increase in gonadosomatic index occured during the months of March. 4. Ripe stage(Stage VII) rapidly increase in March. 5. Early perinucleolus oocyte rapidly develop into late perinucleolus oocytes in March. 6. The vitellogenic phase begins as these late perinucleolus oocytes become transformed into early maturing oocytes through the accumulation of yolk. 7. The cytoplasm completely fills with yolk as oocytes reach the late maturing stage. 8. Changes in the microscopic appearances of the ovaries were well correlated with changes in both gonadosomatic index and macroscopic appearance. 9. It is concluded from these observations that LH plays a major role in sexual maturating of the Israeli carp.

• Fisheries and Aquatic Sciences
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• v.14 no.4
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• pp.379-388
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• 2011

The mechanism by which gonadotropin-releasing hormone (GnRH) and dopamine (DA) control gonadotropin (GTH) release was studied in male and female rainbow trout using cultured pituitary cells obtained at different reproductive stages. The mechanisms of follicle-stimulating hormone (FSH) release by GnRH and DA could not be determined yet. However, basal and salmon-type GnRH (sGnRH)- or chicken-II-type GnRH (cGnRH-II)- induced luteinizing hormone (LH) release increased with gonadal maturation in both sexes. LH release activity was higher after sGnRH stimulation than cGnRH-II stimulation at maturing stages in both sexes. The GnRH antagonist ([Ac-3, 4-dehydro-$Pro^1$, D-p-F-$Phe^2$, D-$Trp^{3,6}$] GnRH) suppressed LH release by sGnRH stimulation in a dose-dependent manner, although the effect was weak in maturing fish. The role of DA as a GTH-release inhibitory factor differs during the reproductive cycle: the inhibition of sGnRH-stimulated LH release by DA was stronger in immature fish than in maturing, ovulating, or spermiated fish. DA did not completely inhibit sGnRH-stimulated LH release, and DA alone did not alter basal LH release. Relatively high doses ($10^{-6}$ or $10^{-5}M$) of domperidone (DOM, a DA D2 antagonist) increased LH release, which did not change with reproductive stage in either sex. The potency of DOM to enhance sGnRH-stimulated LH release was higher in maturing and ovulated fish than in immature fish. These data suggest that LH release from the pituitary gland is controlled by dual neuroendocrine mechanisms by GnRH and DA in rainbow trout, as has been reported in other teleosts. The mechanism of control of FSH release, however, remains unknown.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.55 no.3
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• pp.259-267
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• 2010

This study was performed at Rice and Winter Cereal Crops Department of NICS during 2007 and 2008 to investigate the characteristics of rice leaf emergence and to obtain basic data which can be used for rice growth simulation model by which we can forecast rice growth stage and heading date accurately under different cultivars, transplanting date, and climatic conditions. To confirm leaf emergence rate according to rice maturing ecotype, we surveyed the leaf emergence rate and heading date of Unkwangbyeo, Hwayoungbyeo and Nampyeongbyeo which are early maturing, medium maturing and medium-late maturing cultivars, respectively, according to seedling raising duration and transplanting time. When seedling duration was 15 days, the growth duration between transplanting time and completion of flag leaf emergence on main culm were 51.5~78.3 days in Unkwangbyeo, 55.3~87.9 days in Hwayoungbyeo and 58.4~98.4 days in Nampyeongbyeo, respectively. When seedling duration was 30 days, they were 50.1~75.5 days in Unkwangbyeo, 52.4~84.7 days in Hwayoungbyeo and 56.4~93.8 days in Nampyeongbyeo, respectively. As transplanting time delayed, the emerged leaf number after transplanting decreased in all rice cultivars. The cumulative temperature between transplanting time to completion of flag leaf elongation on main culm were $1,281^{\circ}C{\sim}1,650^{\circ}C$ in Unkwangbyeo, $1,344^{\circ}C{\sim}1,891^{\circ}C$ in Hwayoungbyeo and $1,454^{\circ}C{\sim}2,173^{\circ}C$ in Nampyeongbyeo, respectively. Leaf emergence rate on main culm were precisely represented by equation, y = $y_0$ + a / [1 + exp( - (x - $x_0$) / b)]^c, when we used daily mean temperature as variable.

• Korean Journal of Plant Resources
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• v.35 no.6
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• pp.785-795
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• 2022

Traditional germplasms are unsuitable for mechanized production, limiting adzuki bean production. The creation of cultivars that can be harvested by mechanized means is an urgent task for breeders. The bottom pod height (BPH), lodging resistance, and synchronous maturing of adzuki beans are critical factors for the reduction of losses due to mechanized harvesting. In this study, 14 traits of 806 adzuki bean accessions were analyzed. All growth stages and the yield, lodging score, and synchronous maturing correlated negatively with the BPH. These negative correlations reflect the increased difficulty of breeding to simultaneously satisfy the needs for no lodging, high synchronous maturing rates, BPHs > 10 cm, and high yield. We screened three germplasms with no lodging, high synchronous maturing rates, and BPHs > 10 cm that were used as mechanization-adapted breeding material for crossing with high-yield cultivars. Agronomic trait diversity in adzuki beans was also examined in this study. Principal component and cluster analyses were conducted for 806 germplasms resulting in three clusters with the yield and three growth stage traits serving as the main discriminating factors. Cluster 1 included high-yield germplasms with the number of pods per plant and the number of seeds per pod being the major discriminant factors. Cluster 2 included germplasms with long growth periods and large 100-seed weights while cluster 3 contained germplasms with high BPHs. In general, the characteristics that make mechanical harvesting feasible and those assessed in this study could be utilized to choose and enhance adzuki beans production.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.60 no.2
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• pp.146-152
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• 2015

Early-maturing Korean Japonica cultivars and Jungmo1024 were used as plant materials to evaluate hightemperature tolerance during grain filling stage. National Institute of Crop Science (NICS) in Korea developed Jungmo1024, a mutant line from Namil (wild type) treated by using sodium azide (SA) as mutagen. To evaluate high-temperature tolerance, all cultivars were exposed to high-temperature (day $31.5{\pm}2.5^{\circ}C$/ night $27.5{\pm}1.3^{\circ}C$) and ordinary temperature (day $27.5{\pm}1.8^{\circ}C$/ night $24.7{\pm}1.6^{\circ}C$) during grain filling stage. In these conditions, we performed compared evaluation of grain shape such as length and width and grain quality by using a 1625 Cervitec grain inspector. High-temperature during grain filling stage caused decrease of grain shape. In grain shape such as length and width, the decrease rate of width (average 6.3%) was higher than the decrease rate of length (average 1.3%). Hence, high-temperature affected width of grain than length of grain. In addition, high-temperature showed a decided difference in rate of head rice between ordinary temperature (average 76.3%) and high-temperature (average 13.3%).As a result, Taebong, Ungwang, Manan, and Jungmo1024 seemed relatively a decent high-temperature tolerance than other cultivars. Especially, Jungmo1024 seemed remarkable rate of head rice (average $34.4{\pm}6.2%$) than other cultivars under high-temperature. It is considered that a genetic trait of Jungmo1024 can be useful to improve breeding for high-temperature tolerance.

• Horticultural Science & Technology
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• v.19 no.3
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• pp.329-333
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• 2001

The study was performed to investigate the effect of a plug culture method in the early stage of a potato breeding program. The 105, 200 and 288-cell plug trays were used for raising potato seedlings. The % germination in plug trays ranged between 94 and 96%. Percent tuberization measured at 50 and 60, and 70 days after sowing was the greatest in 105-cell and 200-cell trays, respectively. However, tuberization was most delayed in 288-cell trays. Thus, it is considered that 105-cell tray is the most effective for the selection of early maturing plants. Plant maturity was determined by the morphological characteristics at the seedling stage of stolons cultured in plug trays. Most of seedlings with shorter stolons at seedling stage (1st generation) were the early-maturing, while most of seedlings with longer stolons were the late-maturing at the clonal stage (2nd generation). These results mean that the plant maturity in the early potato breeding program can be effectively grouped by observing the morphological characteristics of stolons after plug culture.