• Korean Journal of Agricultural and Forest Meteorology
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• v.19 no.4
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• pp.246-251
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• 2017

Crop models have been used to predict a heading date for efficient management of fertilizer application. Recently, the ORYZA (v3) model was developed to improve the ORYZA2000 model, which has been used for simulation of rice growth in Korea. Still, little effort has been made to assess applicability of the ORYZA (v3) model to rice farms in Korea. The objective of this study was to evaluate reliability of heading dates predicted using the the ORYZA (v3) model, which would indicate applicability of the model to a decision support system for fertilizer application. Field experiments were conducted from 2015-2016 at the Rural Development Administration (RDA) to obtain rice phenology data. Shindongjin cultivar which is mid-late maturity type was grown under a conventional fertilizer management, e.g., application of fertilizer at the rate of 11 Kg N/10a. Another set of heading dates was obtained from annual reports at experiment farms operated by the National Institute of Crop Science and Agricultural Technology Centers in each province. The input files for the ORYZA (v3) model were prepared using weather and soil data collected from the Korean Meteorology Administration (KMA) and the Korean Soil Information System, respectively. Input parameters for crop management, e.g., transplanting date and planting density, were set to represent management used for the field experiment. The ORYZA (v3) model predicted heading date within 1 day for two seasons. The crop model also had a relatively small error in prediction of heading date for three ecotypes of rice cultivars at experiment farms where weather input data were obtained from a near-by weather station. Those results suggested that the ORYZA (v3) model would be useful for development of a decision support system for fertilizer application when reliable input data for weather variables become available.

• Proceedings of the Botanical Society of Korea Conference
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• 1999.04a
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• pp.17-17
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• 1999

• Korean Journal of Organic Agriculture
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• v.25 no.4
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• pp.805-819
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• 2017

The study was carried out to develop a mathematical model for evaluating the effect of organic fertilizers in organic rice production systems. A function to simulate the nitrogen mineralization process in the paddy soil has been developed and integrated into ORYZA2000 crop growth model. Inorganic nitrogen in the soil was estimated by single exponential models, given temperature and C:N ratio of organic amendments. Data collected from the two-year field experiment were used to evaluate the performance of the model. The revised version of ORYZA2000 provided reasonable estimates of key variables for nitrogen dynamics and crop growth in the organic rice production systems. Coefficient of determination between the measured value and simulated value were 0.6613, 0.8938, and 0.8092, respectively for soil inorganic nitrogen, total dry matter production, and rice yield. This means that the model could be used to quantify nitrogen supplying capacity of organic fertilizers relative to chemical fertilizer. Nitrogen dynamics and rice growth simulated by the model would be useful information to make decision for organic fertilization in organic rice production systems.

• Korean Journal of Plant Resources
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• v.27 no.3
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• pp.249-255
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• 2014

The rice belonging to Oryza sativa is not only has significant economic importance, for it is the major source of nutrition for about 3 billion all around the world. But also plays a vital role as a model organism, because it has a number of advantages to be a model plant, such as efficient transformation system and small genome size. Many methods and techniques have been conducted to attempt to distinguish different Oryza sativa species, such as amplified fragment length polymorphism (AFLP), random amplified polymorphic DNA (RAPD), simple sequence repeat (SSR) and so on. However, studies using sequence analysis of internal transcribed spacer (ITS), a region of ribosomal RNA has not been reported until now. This study was undertaken with an aim to understand the phylogenetic relationships among sixteen isolates of Oryza sativa collected from abroad and fifteen isolates collected from Korea, using ribosomal RNA (rRNA) internal transcribed spacer (ITS) sequences to compare the phylogeny relationships among different Oryza sativa species. The size variation obtained among sequenced nuclear ribosomal DNA (nrDNA) ITS region ranged from 515bp to 1000bp. The highest interspecific genetic distance (GD) was found between Sfejare 45 (FR12) and Anapuruna (FR15). Taebong isolate showed the least dissimilarity of the ITS region sequence with other thirty isolates. This consequence will help us further understanding molecular diversification in intra-species population and their phylogenetic analysis.

• Korean Journal of Plant Taxonomy
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• v.39 no.3
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• pp.199-215
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• 2009

Phytoliths formed on the leaf-blades of the seventeen Oryza species were examined using back-scattered electron imaging. The resulting descriptions of the phytoliths became the basis for a new key to the species of the genus. This key includes features useful for specific identification related to the silica bodies originating from epidermal cells upon both the mid-vein and bulliform cell, as well as of phytoliths originating from papillae, prickle hairs, large and small trichomes, and stomatal apparatus. These detailed phytolith descriptions, back-scattered electron images, and keys to both adaxial and abaxial sides of leaves, can now be used in identifying phytoliths from archaeological samples as well as extant species of Oryza.

• Preventive Nutrition and Food Science
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• v.7 no.2
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• pp.119-122
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• 2002

Oryza sativa cv. Mihyangbyo is one of several recently developed varieties of rice; characterized by high levels of aromatic components, which may increase its sensory and nutritional properties. In conjunction with our continuing investigation of bioactive components of improved grain varieties, a quinolone alkaloid was isolated from the n-butanol soluble fraction of the aleurone layer of Oryza sativa cv. Mihyangbyo (Gramineae) through activity-guided fractionation and isolation. The compound exhibited moderate antineoplastic activity in a human leukemia cell line (U937) with an $IC_{50}$/ value of 118.1 ug/mL, based on the MTT(3-[4, 5]dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide) cell proliferation assay. The chemical structure of the functional compound was determined, based on physical and spectroscopic characteristics.

• Journal of Plant Biology
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• v.39 no.4
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• pp.237-242
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• 1996

Epidermal leaf cell phytoliths of 17 species of Oryza were examined with backscattered electron imaging with scanning electron microscopy to determine the usefulness of phytolith morphology for systematic studies. Many kinds of identifiable phytolith morphology are observed in the leaf blades of Oryza. They are different among species as well as between adaxial and abaxial surface and costal and intercostal strip portions of leaf blades. Distinguishing phytolith characters are useful at the level of the section, such as Angustifoliae, Ridleyanae, and Granulatae. The results of a cluster analysis using 21 qualitative characters of phytoliths reveal many taxonomic characteristics which are compatible with current taxonomy.

• Proceedings of the Botanical Society of Korea Conference
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• 2002.04a
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• pp.102-102
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• 2002

• Molecules and Cells
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• v.27 no.4
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• pp.459-465
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• 2009

MUG1 is a MULE transposon-related domesticated gene in plants. We assessed the sequence diversity, neutrality, expression, and phylogenetics of the MUG1 gene among Oryza ssp. We found MUG1 expression in all tissues analyzed, with different levels in O. sativa. There were 408 variation sites in the 3886 bp of MUG1 locus. The nucleotide diversity of the MUG1 was higher than functionally known genes in rice. The nucleotide diversity (${\pi}$) in the domains was lower than the average nucleotide diversity in whole coding region. The ${\pi}$ values in nonsynonymous sites were lower than those of synonymous sites. Tajima D and Fu and Li $D^*$ values were mostly negative values, suggesting purifying selection in MUG1 sequences of Oryza ssp. Genome-specific variation and phylogenetic analyses show a general grouping of MUG1 sequences congruent with Oryza ssp. biogeography; however, our MUG1 phylogenetic results, in combination with separate B and D genome studies, might suggest an early divergence of the Oryza ssp. by continental drift of Gondwanaland. O. long-istaminata MUG1 divergence from other AA diploids suggests that it might not be a direct ancestor of the African rice species.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.6
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• pp.759-765
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• 1997

The process of the senescence in Oryza glaberrima Steud. strains and Oryza sativa L. cultivars were examined in terms of SPAD value(chlorophyll content) and photosynthetic rate. SPAD values and photosynthetic rates of flag leaves for 10 genotypes of each species was measured at the 1, 3 and 5 weeks after heading. SPAD values and photosynthetic rates of O. glaberrima strains tended to decrease rapidly after heading. O. sativa cultivars showed slower decrease as compared to O. glaberrima strains, in particular during the period from 1 to 3 weeks after heading. Although there was no significant difference between the two species in the mean value of photosynthetic rate and SPAD value at 1 weeks after heading, O. glaberrima had lower values after 3 weeks after heading. There were significant positive correlation coefficients between the photosynthetic rate and the SPAD value at 1 and 3 weeks after heading for O. glaberrima strains, and at 1 and 5 weeks after heading for O. sativa cultivars. There were significant positive correlation between the decreasing rates of the photosynthetic rates and the decreasing rates of the SPAD values at the period from the 1 to 3 weeks after heading for both species. At the period from 3 to 5 weeks after heading, only O. glaberrima showed a significant correlation between two traits, indicating that rapid decrease in chlorophyll content would affect the photosynthesis in O. glaberrima.