• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.304-304
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• 2017

In semi-arid countries such as Namibia, the flooding unexpectedly happens in a rainy season, causing losses in the yield of upland-adapted cereal crop. In flooding conditions, rice roots sequentially form aerenchyma and a barrier to radial oxygen loss (ROL), and oxygen is released into the rhizosphere near the root tips. Iijima et al. (2016) and Awala et al. (2016) reported that close mixed-planting with rice can mitigate the flood stress of co-growing upland-adapted cereal crop by modifying their rhizosphere microenvironments via the oxygen released from the rice roots. Moreover, by using the model system of hydroponic culture, it was confirmed that oxygen from rice roots was transferred to co-growing upland-adapted cereal crop in close mixed planting system (Kawato et al., 2016). However, it is not sure whether the ability of oxygen release varies among rice cultivars, because Kawato et al. (2016) used only one japonica cultivar, Nipponbare (Oryza sativa). The objective of this study was to compare the ability of oxygen release in rhizosphere among rice cultivars. The experiment was conducted in a climate chamber in Kindai University. We used 10 rice cultivars from three different rice species (O. sativa (var. japonica (2), var. indica (3)), Oryza glaberrima Steud. (2) and their interspecific progenies (3)) to compare the ability of oxygen release from the roots. According to the method by Kawato et al. (2016), the dissolved oxygen concentration of phase I (with shoot) and phase II (without shoot) were measured by a fiber optic oxygen-sensing probe. The oxygen released from rice roots was calculated from the difference of the measurements between phase I and phase II. The result in this study indicated that all of the rice cultivars released oxygen from their roots, and the amount of released oxygen was significantly correlated with the above-ground biomass (r = 0.710). The ability of oxygen release (the amount of the oxygen release per fresh root weight) of indica cultivars (O. sativa) tended to be higher as compared with the other cultivars. On the other hand, that of African rice (O. glaberrima) and the interspecific progenies tended to be lower. These results suggested that the ability of oxygen release widely varies among rice cultivars, and some of indica cultivars (O. sativa) may be suitable for close mixed-planting to mitigate flood stress of upland-adapted cereal crop.

• Proceedings of the Korean Society of Crop Science Conference
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• 2005.10b
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• pp.330-331
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• 2005

• The Plant Pathology Journal
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• v.37 no.4
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• pp.375-388
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• 2021

Rice yellow mottle virus (RYMV) is the most harmful virus that affects irrigated and lowland rice in Africa. The RBe24 isolate of the virus is the most pathogenic strain in Benin. A total of 79 genotypes including susceptible IR64 (Oryza sativa) and the resistant TOG5681 (O. glaberrima) as checks were screened for their reactions to RBe24 isolate of RYMV and the effects of silicon on the response of host plants to the virus investigated. The experiment was a three-factor factorial consisting of genotypes, inoculation level (inoculated vs. non-inoculated), and silicon dose (0, 5, and 10 g/plant) applied as CaSiO₃ with two replications and carried out twice in the screen house. Significant differences were observed among the rice genotypes. Fifteen highly resistant and eight resistant genotypes were identified, and these were mainly O. glaberrima. Silicon application did not affect disease incidence and severity at 21 and 42 days after inoculation (DAI); it, however, significantly increased plant height of inoculated (3.6% for 5 g CaSiO₃/plant and 6.3% for 10 g CaSiO₃/plant) and non-inoculated (1.9% for 5 g CaSiO₃/plant and 4.9% for 10 g CaSiO₃/plant) plants at 42 DAI, with a reduction in the number of tillers (12.3% for both 5 and 10 g CaSiO₃/plant) and leaves (26.8% for 5 g CaSiO₃/plant and 28% for 10 g CaSiO₃/plant) under both inoculation treatments. Our results confirm O. glaberrima germplasm as an important source of resistance to RYMV, and critical in developing a comprehensive strategy for the control of RYMV in West Africa.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.94-94
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• 2017

Oryza sativa and Oryza glaberrima are rice cultivars distributed in Asia and Africa. There are several differences between these cultivars in morphological characteristics such as panicle structure and especially the secondary branch number of O. glaberrima is less than that of O. sativa. Generally, branch number of panicle related to a large vascular bundle number (VBN) among O. sativa and there is a wide variation of the VBN of the peduncle from where the bundles enter into the rachis branches. However, there is less information about VBN in O. glaberrima and also the relationship between VBN and branch numbers, the primary branch number (PBN) and secondary branch number (SBN). Additionally, the genetic factor for VBN and branch number in O. glaberrima is not completely exploited. In this study, phenotypic variation for VBN and panicle structure were investigated using a set of 40 $BC_3$ -derived from IRGC 104038 (O. glaberrima from Senegal) and 35 $BC_4$ -derived from IRGC103777 (O. glaberrima from Mali) introgression lines with a genetic background of japonica rice Taichung 65. Taichung 65 had 11.8 PBN, 16.0 SBN and 11.5 VBN, while IRGC 103777 had 12.0 PBN, 15.0 SBN and 15.3 VBN. The introgression lines derived from IRGC 104038 had range from 9.0 to 14.4 in the PBN, range from 9.6 to 33.5 in the SBN and range from 9.8 to 14.8 in the VBN. Additionally, the introgression lines derived from IRGC 103777 had range from 9.0 to 18.5 in the PBN, range from 10.3 to 39.0 in the SBN and range from 9.0 to 15.3 in the VBN. Among two set of introgression lines, there are significant correlation between VBN and PBN. Multiple introgression lines indicated higher PBN, SBN and VBN than Taichung 65 and these examined characteristics are supposedly controlled by quantitative traits loci. The genetic factor related to VBN and panicle architecture can be revealed using segregating population in future study.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.5
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• pp.696-701
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• 2016

This study was conducted to evaluate the effects of heat treatment and germination on tricin and tricin 4'-O-(threo-${\beta}$-guaiacylglyceryl) ether (TTGE) formation from rice hull (Oryza sativa L.). Heat treatments were conducted at $80{\sim}140^{\circ}C$ for 1~5 h. Germination periods were 1~6 days at $37^{\circ}C$. Germinated rough rice extracts were classified as non-filtrated, filtrated, and residue after filtration. For heat treatment, the highest contents of tricin and TTGE were 253.12 and $208.39{\mu}g/g$ at $130^{\circ}C$ after 1 h, respectively. For germination, the highest contents of tricin and TTGE in rice hull were 118.20 and $95.37{\mu}g/g$ after 2 days, respectively. In the germinated rough rice extract treatment, the highest contents of tricin and TTGE were 361.76 and $308.08{\mu}g/g$, respectively, in residue after filtration of germinated rice extract for 6 days. Therefore, the optimum conditions for tricin and TTGE formation were heat treatment at $130^{\circ}C$ for 1 h, germination for 2 days, and addition of residue after filtration of germinated rough rice extract for 6 days.

• The Korean Journal of Food And Nutrition
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• v.36 no.6
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• pp.506-514
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• 2023

Reported positive ion fragmentation of phenolic acid derivatives in rice (Oryza sativa L.) were summarized based on the literature. A total of eight phenolic acids (4 derivatives of ferulic acid, 3 derivatives of sinapic acid and p-coumaric acid) were isolated and identified from rice (raw and steamed) using UPLC-DAD-QToF/MS. Results revealed that 6-O-feruloylsurose was the major component with 3'-O-sinapoylsucorse being tentatively identified in Oryza sativa L. for the first time as a new hydroxycinnamoyl derivative in rice grains. In our study, raw brown rice had the highest phenolic acid contents with Samkwang showing higher phenolic acid content than Saeilmi and Sindongjin (12.41 vs. 7.89 and 3.10 mg/100 g dry weight, respectively). Of all varieties, brown rice had higher phenolic acid contents than white rice. These contents decreased considerably when rice was steamed whereas, p-coumaric acid and ferulic acid contents were increased. Additionally, contents of rice (raw and steamed) can be used as a fundamental report for new rice varieties.

• Proceedings of the Korean Society of Potoscience Conference
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• 2006.06a
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• pp.23-23
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• 2006

• Korean Journal of Breeding Science
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• v.41 no.2
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• pp.101-105
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• 2009

Rice (Oryza sativa L.), the world's most important crop, is usually classified into ssp. indica and japonica based on morpho-physiological traits. In the previous study, we have developed subspecies-specific STS markers (SS markers) to readily discriminate between indica and japonica in O. sativa. In this study, we employed SS markers to investigate the genomic inclination of worldwide collections of O. sativa. A total of 320 varieties were divided into two groups with 63 SS markers. Namely, they formed two distinctive groups, indica and japonica, as expected by their geographic origin. The population structure analysis revealed that the variability of genetic background was greater in indica than in japonica. Some of them, however, exhibited intermediate genomic inclination between indica and japonica. These results are in general agreement with the previous studies, suggesting that SS markers are powerful tools for both determination of subspecies genome and assessment of genetic diversity in rice.

• Proceedings of the Korean Society of Crop Science Conference
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• 2000.11a
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• pp.83-85
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• 2000

• Journal of Life Science
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• v.20 no.8
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• pp.1173-1180
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• 2010

We investigated changes in photosynthesis and activity of ascorbate peroxidase (APX) that scavenges ROS as responses to oxidative stress induced by salinity in rice (Oryza sativa L.). Photosynthetic efficiency of rice leaves, monitored in terms of Fv/Fm, declined with the increase of salt concentration (100-300 mM NaCl). Salinity caused an increase of $H_2O_2$ in leaves of rice, with an increase of APX activity. Among total APX isoforms, an isoform of stromal-APX 1 in leaves of rice was completely inactivated by 300 mM NaCl, but was not affected by chilling or drought. The results suggest that salt stress acts in quite a different mechanism in relation to the activity of stromal-APX from that of other stresses such chilling and drought. We carried out RT-PCR for analysis of genes expression of APX isoforms as affected by salt stress. The expression of cytosolic APX/thylakoid-bound APX genes in leaves of rice exposed to salt stress was increased, while stromal APX gene expression rapidly declined.