• Korean journal of applied entomology
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• v.41 no.2
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• pp.85-89
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• 2002

Development and reproduction of the rice armyworm, Pseudaletia separara, were investigated on different diets (corn leaf, rice leaf, Chinese cabbage leaf, cabbage leaf, sweetpotato leaf, soybean leaf and silkworm artificial diet). Egg and pupal periods were not different among the diets. But larval periods showed significant difference among diets. Developmental period from egg to adult was shortest as 32.5 d on corn leaf and longest as 46.6 d on soybean leaf. At 16 days after hatching, larval weights on rice and silkworm artificial diet were heavier than those on other diets. The larvae reared on cabbage leaf and sweetpotato leaf failed to pupate. Survival rates from larva to adult were highest (70.6%) on com leaf lowest (39.8%) on soybean leaf. The longevity of female adults was not affected by the larval diets. Female adults showed higher fecundity when the larvae were fed with corn leaf, rice leaf and silkworm artificial diet than other diets. Net reproduction rate (R$_{0}$) was highest as 1218.5 on silkworm artificial diet. The intrinsic rate of natural increase (R$_{0}$) ranged from 0.115 to 0.175, and was maximum on com leaf.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.3
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• pp.226-235
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• 2002

This experiment was to evaluate lodging characteristics of 35 recommended rice varieties of Kyonggi-do at normal (110 kg N/ha) and hen (220 kg N/ha) nitrogen application rates during 1999 to 2000. At heavy N fertilization rate, varieties that were highly resistant to lodging were Obongbyeo, Daejinbyeo, Naepoongbyeo, Nonganbyeo and Ilpumbyeo. Fourteen varieties including Daeanbyeo were moderately resistant and 11 varieties including Jinbubyeo were susceptible to lodging. The lodging-related characters which showed the highest effect on lodging at lodging degree of 9 were culm length and height of center gravity, culm length at lodging degree of 5, and culm length and the third internode length at lodging degree of 3 or below. The difference in rice yield between normal and heavy nitrogen fertilization rate was within 5% in early-maturing varieties but there was great yield difference in mid- and late-maturing varieties depending on the degree of lodging. Consequently, stable rice yield could be obtained by selecting lodging-resistant varieties and lowering fertilization rate, specially in the paddy field where lodging occurrence is common.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.192-192
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• 2017

Direct-seeding cultivation of rice is increasing in Asia instead of transplanting system, because of its lower cost and operational simplicity. Low-temperature germinability (LTG) and anaerobic germinability (AG) are important characters for breeding of varieties for wide-spread adoption of direct-seeding cultivation in rice. This study was performed to characterize LTG and AG of seven rice varieties and identify varieties with strong germinability on both low-temperature and anaerobic conditions. The mean germination rate and germination vigor of seven varieties were 51.7% and 6.0 under low-temperature condition, respectively. Among these varieties, Cheongcheongjinmi and Hwanggeumnodeul had the highest germination rate of 80%, indicating that Cheongcheongjinmi and Hwanggeumnodeul have a good LTG. In anaerobic conditions, the germination rate and coleoptile length for all varieties were 47.6% and 3.2 cm, respectively. Of them, the highest germination rate and coleoptile length were observed in Subo and Hopum, respectively, suggesting that these two varieties are tolerant to anaerobic during germination stage. Molecular characterization by SDS-PAGE revealed that the protein patterns differed at 50 kDa, 40 kDa, and 22 kDa between low-temperature and anaerobic conditions. Varieties identified as good LTG or AG in this study may be used for developing new direct-seeding rice cultivars through pyramiding these traits in the breeding program.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.71-71
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• 2017

Stable stand establishment is pre-requisite in direct rice seeding system for obtaining optimal yield of rice crop in rain-fed and waterlogged areas. Anaerobic condition on waterlogged soil causes low germination which significantly reduces crop yield. Due to low availability of tolerant genetic material for anaerobic germination, there is urgent need to evaluate rice germplasm for better germinability under anaerobic conditions. Seeds of the 185 rice accessions were evaluated for germination vigor and coleoptile length under anaerobic conditions. The variation among germplasm was tested for significance using analysis of variance and various multivariate components. Significant level of variation was observed among all accessions for germination vigor and coleoptiles length. Although highest mean values for coleoptiles length (2.1cm) and germination rate (60%) were observed in japonica accessions but maximum coleoptile length (4.68cm) and germination rate (96%) was found in indica genotype CO18. A highly significant and positive correlation was also observed between germination vigor and coleoptiles length, which signify the importance of elongated coleoptile under anaerobic conditions. The PCA analysis illustrated that 97.24% variation was accounted by PC1 while PC2 and PC3 explained 2.54% and 0.24% variation for germination vigor and coleoptile length. PCA scattered plot divided the accessions in four various groups. All AG tolerant accessions were included in group I. Likewise in the case of cluster analysis, two major clades (I and II) were formed. All accessions showing >40% germination rate were included in clade I, whereas all other accessions with <40% germination rate were grouped in clade II. Further more highly tolerant accessions (>80% germination) were grouped in sub-cluster IA.

• Korean Journal of Food Science and Technology
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• v.16 no.4
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• pp.457-462
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• 1984

Cooking rate calculated from hardness change, and gelatinization aspects observed by X-ray diffraction and scanning electron microscope of brown rice were investigated. Optimum ratio of water to rice of Akibare and Milyang 23 was 1.65 and 1.73, respectively. Milyang 23 was cooked at a faster rate than Akibare. Cooking rate of brown rice was about an half of white rice. The temperature dependence of cooking rate of brown rice was found to be relatively low. The activation energy for cooking were in the range of 15,000 to 16,400 cal/mol at 80 to $100^{\circ}C$ and 8,200 to 8,600 cal/mol at 100 to $130^{\circ}C$. The gelatinization degree determined from X-ray diffractometry was approximately consistent with the cooking degree expressed by reciprocal hardness.

• Korean Journal of Organic Agriculture
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• v.19 no.spc
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• pp.174-177
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• 2011

Green manure crops play an important role in organic farming. Field experiment was conducted at paddy soil (fine loamy, mixed, nonacid, mesic family of Aeric Fluvaquentic Endoquepts) in 2008/2009 to 2009/2010 at the National Institute of Crop Science (NICS), RDA, Suwon, Gyeonggi province, Korea. This experiment was carried out to evaluate the biomass of hairy vetch (Vicia villosa) and growth of rice (Oryza sativa) by different seeding rates. Seeding rates of hairy vetch consisted of 30, 60, and 90 kg $ha^{-1}$ by broadcasting before rice harvesting. The biomass and nitrogen production of hairy vetch were not significantly different between 60 kg $ha^{-1}$ and 90 kg $ha^{-1}$ of seedinq rates. Also, rice yield was not significantly different between seeding rate 60 kg $ha^{-1}$ of hairy vetch and conventional practice for two years. Therefore, we suggested that seeding rate of hairy vetch should be reduced by continuous cropping and incorporation of hairy vetch under rice-based cropping system.

• Korean Journal of Soil Science and Fertilizer
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• v.20 no.3
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• pp.231-240
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• 1987

With a purpose to obtain basic informaton for improving poorly drained soil, a pot experiment was conducted about the effect of percolation rate on growth and yield of rice under application of wollastonite and rice straw as soil conditioner. The sandy and clayey soils were selected to compare difference in effectiveness of poor drainage. The results were summarized as follows: 1. Increasing or percolation rate increased rice yield in both sandy and clayey soils, but the effectiveness on yield increase was greater in clayey soil than in sandy. 2. Various materials of soil solution produced from the process of soil reduction were high at the early growing stage, but they were gradually decreased at the later growing stage. 3. With increasing percolation rate, the contents of N, $P_2O_5$ and $K_2O$ in rice plant were decreased, but that of $SiO_2$ was increased. 4. The number of roots at harvest was greater with increased extension as infiltration rate was increased.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.43 no.1
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• pp.1-5
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• 1998

Experiments were carried out to find out the optimum water potential, temperature, and duration for the priming of rice seeds, Oryza sativa L. (cv. Ilpumbyeo) for better germination at sub-optimal temperatures. Seeds were primed in 0, -0.2, -0.4, -0.6, -0.8, and -1.0 MPa PEG (polyethylene glycol) solutions at $25^{\circ}C$. The optimum water potential for seed priming, the highest water potential at which rice seeds did not germinate, was -0.6 MPa. To find out optimum priming temperature and duration rice seeds were primed in -0.6 MPa PEG solution and 0 MPa (water as a control) for various durations at 15 and $25^{\circ}C$ and the seeds were germinated at 17, 20, and $25^{\circ}C$. Considering germination rate and speed, the optimum priming time in water (0 MPa) was 4 days at 15$^{\circ}C$ and 1 day at $25^{\circ}C$, while 4 days was the optimum priming time in a -0.6 MPa PEG solution, regardless of the priming temperature. Priming reduced the actual time of germination, especially at sub-optimal temperatures. Priming did not affect germination rate in -0.6 MPa PEG solution at 15$^{\circ}C$, but overpriming reduced the final germination rate in water at 15$^{\circ}C$ and in -0.6 PEG solution at $25^{\circ}C$. Total sugars and $\alpha$-amylase activity induced during the seed priming were negatively correlated with the final germination rate and there was no noted relationship with the speed or uniformity of germination.

• Journal of the Korean Dietetic Association
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• v.15 no.4
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• pp.397-404
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• 2009

In this study, we examined food intake, sodium intake, and satiety rate for different methods of consuming soup. Healthy young women (n=50) participated in this study. The subjects ate cooked rice and soup using a method that they preferred and then they were assigned into separate intake groups based on how they consumed their rice and soup. One group consisted of women that ate their soup and cooked rice separately (separate intake group, n=30). The second group consisted of the women who mixed the rice and the soup prior to consumption (mixed intake group, n=20). The mixed intake group consumed significantly more food (p<0.001) and sodium (p<0.05) than the separate intake group. Because of the high water content and ease of swallowing for the mixed intake method, the eating rate of the mixed intake group (42.5 g/min) was significantly higher than that of the separate intake group (28.8 g/min) (p<0.01). However, despite consuming 79.5 g more food at lunch, the rates of satiety were not significantly different before and after eating between the mixed intake and separate intake group. Therefore, eating rate, consumption norms and concept of "clean one's bowl" may influence food intake and sodium intake. Although more studies are needed, these data suggest eating cooked rice and soup separately may help to control obesity and hypertension.

• Culinary science and hospitality research
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• v.21 no.6
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• pp.218-228
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• 2015

In this study, the physicochemical characteristics of rice sourdough fermented with Omija extract were investigated. Rice sourdough was made with a 3 stage fermentation process. pH & total titratable acidity, numbers of yeast and lactic acid bacteria, and dough expansion rate were measured. In addition, an RVA was employed to study the pasting properties of rice sourdough. There was a significant (p<0.05) change in both the pH of rice sourdough, which decreased from 5.08 to 3.98, and total titratable acidity, which increased from 0.20 to 0.57 (0.1N NaOH mL), as fermentation time increased. The amount of yeast and lactic acid bacteria significantly increased from 6.73 to 7.65 log CFU/g, 6.93 to 7.65 log CFU/g, respectively(p<0.05). The expansion rate of rice sourdough fermented with Omija extract was higher than rice sourdough fermented without Omija extract. The initial pasting temperatures of rice sourdough fermented with Omija extract were decreased from $91.3^{\circ}C$ to 85.6. The final viscosity and setbacks decreased as fermentation time increased. These results suggest that Omija extract has a beneficial effect on increasing the expansion rate of rice sourdough as a substitute for wheat flour.