• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.284-284
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• 2022

The overall effects of gibberellic acid (GA3) with NaCl on different rice genotypes are inadequately understood. The present study determines the effect of different GA3 concentrations on the morphophysiological, molecular and biochemical effects of 120 mM NaCl salt stress in rice seedlings. Salt stress reduced germination percentages and seedling growth and decreased bioactive GA content. It also downregulated the relative expression of a-amylase-related genes - OsAmy1A, OsAmy1C, and OsAmy3C in the salt-sensitive IR28 cultivar. Salt stress differentially regulated the expression of GA biosynthetic genes. Salt stress increased antioxidant activity in all rice genotypes tested, except in IR28. GA3 (50 and 100 µM) mitigates the effect of salt stress, rescuing seed germination and growth attributes. GA3 significantly increased bioactive GA content in Nagdong and pokkali (50 µM) and Cheongcheong and IR28 (100 µM) cultivars. The a-amylase genes were also significantly upregulated by GA3. Similarly, GA3 upregulated OsGA2oxl and OsGA2ox9 expression in the Cheongcheong and salt-sensitive IR28 cultivars. The present study demonstrated that salt stress inactivates bioactive GA - inhibiting germination and seedlings growth - and decreases bioactive GA content and GSH activity in IR28 and Pokkali cultivars. Further, GA3 significantly reversed the effects of 120 mM NaCl salt stress in different rice genotypes. The current study also suggests if we know the coastal area water NaCl concentration we can apply the exogenous GA3 accordingly. Thus, we would be able to grow rice cultivars near the coastal area and reduce the rice damage by salinity.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.49 no.1
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• pp.52-60
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• 2004

The optimized in vitro culture system was investigated for improvement of regeneration efficiencies by observing the responses of scutella-derived callus of Korean rice (Oryza sativa L.). Large variations of callus induction (43.9-93.9%) and shoot regeneration (0-88.7%) were observed among the rice cultivars depending on medium. However, shoot regeneration was significantly improved by selected utilization of basal medium, growth regulators, and carbon sources. N6 basal medium was more efficient for embryogenic callus induction than MS or LS basal medium, while MS was superior to N6 for shoot regeneration. The calli of highly regenerative cultivars grew faster and showed higher rates of green tissue formation (GT) and shoot regeneration (SR) and lower rate of callus browning (CB) than those of recalcitrant cultivars. Although a higher level of kinetin stimulated the GT and SR in highly regenerative cultivars, $10\textrm{mgL}^{-1}$ kinetin generally suppressed the GT and SR, while CB was accelerated compared to $2\textrm{mgL}^{-1}$ kinetin. Additional benefits of sorbitol combined with maltose (or sucrose) under $5\textrm{mgL}^{-1}$ kinetin were certainly confirmed on regeneration efficiencies compared to sucrose alone as carbon source and osmotic regulator. This combination showed high rate of GT and SR with multiple shoots while low rate of CB. With MSRK5SM-Pr medium ($5\textrm{mgL}^{-1}$ kinetin, 3% sorbitol, 2% maltose, $500\textrm{mgL}^{-1}$ proline), the regeneration efficiencies of total 17 out of 24 cultivars were practically improved 160% on average compared to MSRK2S ($2\textrm{mgL}^{-1}$ kinetin, 3% sucrose) control medium. Especially, the medium was most effective to the cultivars showing a medium level of regenerability such as Daesanbyeo and Dongjinbyeo and Suwon477, enhancing efficiencies more than 300-600% compared to MSRK2S medium.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.44 no.2
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• pp.149-153
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• 1999

Prediction of rice developmental stage is necessary for proper crop management and a prerequisite for growth simulation as well. The objectives of the present study were to find out the relationship between the plastochrone index(PI) and the developmental index(DVI) estimated by non-parametric phenology model which simulates the duration from seedling emergence(DVI=0) to heading(DVI=l) by employing daily mean air temperature and daylength as predictor variables, and to confirm the correspondency of developmental indice to panicle developmental stages based on this relationship. Four japonica rice cultivars, Kwanakbyeo, Sangpungbyeo, Dongjinbyeo, and Palgumbyeo which range from very early to very late in maturity, were grown by sowing directly in dry paddy field five times at an interval of two weeks. Data for seedling emergence, leaf appearance, differentiation stage of primary rachis branch and heading were collected. The non-parametric phenology model predicted well the duration from seedling emergence to heading with errors of less than three days in all sowings and cultivars. PI was calculated for every leaf appearance and related to the developmental index estimated for corresponding PI. The stepwise polynomial analysis produced highly significant square-rooted cubic or biquadratic equations depending on cultivars, and highly significant square-rooted biquadratic equation for pooled data across cultivars without any considerable reduction in accuracy compared to that for each cultivar. To confirm the applicability of this equation in predicting the panicle developmental stage, DVI at differentiation stage of primary rachis branch primordium was calculated by substituting PI with 82 corresponding to this stage, and the duration reaching this DVI from seedling emergence was estimated. The estimated duration revealed a good agreement with that observed in all sowings and cultivars. The deviations between the estimated and the observed were not greater than three days, and significant difference in accuracy was not found for predicting this developmental stage between those equations derived for each cultivar and for pooled data across all cultivars tested.

• The Korean Journal of Food And Nutrition
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• v.31 no.5
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• pp.760-765
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• 2018

In order to observe physical properties of rice depending on reheating, the study cooked rice developed for high quality cooked rice and analyzed physical properties of rice depending on reheating following 24 hr refrigeration. As a result of palatability of cooked rice, Samgkwang had the lowest hardness, while Daebo and Haiami had the highest one. With respect to adhesiveness, toughness and stickiness, Sindongjin exhibited lowest properties. After cooking each rice by cultivars, the study observed their color, texture properties, and microstructure immediately after cooking, after 24 hr of refrigeration and further on. Lightness of cooked rice tended to drop because of refrigeration and reheating. Analysis of texture properties after cooking revealed that Haiami marked the highest points in all categories. When stored for 24 hr after cooking, hardness, viscosity and chewiness increased in cooked rice followed by a decrease after reheating. Observation of the microstructure of cooked rice using a scanning electron microscope revealed that Haiami had its particles in the center as closely condensed. It was apparent that all the cultivars formed stoma in an obvious manner because of refrigeration and reheating. The results of the present study show that physical properties of cooked rice varied according to reheating after cooking and storage depending on the inherent characteristics of rice cultivars.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.57 no.2
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• pp.160-165
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• 2012

A field study was conducted at Miryang in 2011 to evaluate differential sensitivity of six rice cultivars, three Indica${\times}$Japonica rice (long grain, cv. Hanareumbyeo, Hanareum2, Dasanbyeo) and three Japonica rice (short grain, Nampyung, Ilpumbyeo and Junamjosaeng) cultivars, to benzobicyclon, mesotrione+pretilachlor (MP) and butachlor (control) in transplanting rice and their treatment influences on rice yield. All Indica${\times}$Japonica rice cultivars exhibited susceptible to both benzobicyclon and MP as reflected by higher visual injury and carotenoid biosynthesis inhibition when compared with Japonica rice cutlivars. The percentage of foliar chlorosis of Indica${\times}$Japonica rice was only 0.9~4.7% for benzobicyclon at 13 days after treatment (DAT) and 30.3~64.4% for MP at 5DAT but it increased rapidly to 88.4~91.2% at 12~20DAT. However, most of the Japonica cultivars are tolerant to bezobicyclon and MP. There was no visible leaf chlorosis but carotenoid biosynthesis was slightly inhibited. Based on relative carotenoid content reduction of benzobicyclon and MP to butachlor, the Indica${\times}$Japonica rice showed 4.6~15.6 fold higher compared with the Japonica rice. The heading date of the injured rice plant was delayed by 3 days and panicle number per square meter and ripened grain ratio were reduced as compared with the control treatment of butachlor. Rice yield of the Indica${\times}$Japonica rice cultivars treated with benzobicyclon and MP was reduced by 7~10%, 3~5%. respectively. The result indicates that rice cultivars vary in tolerance to HPPD-Inhibiting herbicides and Indica${\times}$Japonica rices were more susceptible than the Japonica rices to MP and benzobicyclon. Rice yield of the Indica${\times}$Japonica rices was also significantly reduced by the those herbicide treatments.

• Korean Journal of Environmental Agriculture
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• v.28 no.1
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• pp.53-58
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• 2009

The propose of this study was to find out optimum conditions for no-tillage rice-winter cover crops cropping system. A field research was conducted to evaluate productivity and quality of rice cultivars (Dongjinbyeo and Junambybyeo) in rice-winter cover cropping systems at Doo-ryangmyeon., Sacheon, Gyeongsangnam-do, Korea from January 2005 to October 2006. The experimental soil was Juggog series (fine silty, mesic family of Fluvaquentic Eutrndepts). The rice cultivars were experimented under some different high residue farming systems, i.e. no-tillage no treatment (NTNT), no-tillage amended with rice straw (NTRS), no-tillage amended with rye (NTR), no-tillage amended with Chinese milkvetch (NTCMV), tillage no treatment (TNT), and conventional cropping system (Control). The miss-planted rate was 8.8% in 2005 and range of 10.8% to 13.3% in 2006 at NTR, and the other treatments were carried out at miss-planted rate ranging from 1.2% to 5.0%. Tiller numbers of Junambyeo, and Dongjinbyeo in both of years were the highest in Control, and decreased nearly in NTCMV, NTR, NTRS, NTNT, and TNT in that order. The lowest grain yield was observed in TNT both cultivars due to the lower tiller numbers per area, and spikelet numbers per panicle. Also, no-tillage treatments were lower grain yield than control. On the other hand, 1,000-grain weight was lowest in control due to higher tiller numbers per area, and spikelet numbers per panicle. Ripened grain ratio was a similar aspect in all treatments. The palatability score of milled rice was lowest in control while protein content of milled rice was highest in control. The NTCMV was considered an effective sustainable farming practice for rice yield and quality.

• Proceedings of the Korean Society of Sericultural Science Conference
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• 1997.06a
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• pp.23-49
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• 1997

This is a progress report of rice biotechnology including development of gene transformation system, gene cloning and molecular mapping in rice. The scope of the research was focused on the connection between conventional breeding and biotech-researches. Plant transformation via Agrobacterium or particle bombardment was developed to introduce one or several genes to recommended rice cultivars. Two chimeric genes containing a maize ribosome inactivating protein gene (RIP) and a gerbicide resistant gene (bar) were introduced to Nipponbare, a Japonica cultivar, and transmitted to Korean cultivars. The homozygous progenies of herbicide resistant transgenic plant showed good fertility and agronomic characters. To explore the genetic resourses in rice, over 8,000 cDNA clones from immature rice seed have been isolated and sequenced. About 13% of clones were identified as enzymes related to metabolic pathway. Among them, twenty clones have high homology with genes encoding enzymes in the photorespiratory carbon cycle reaction. Up to now about 100 clones were fully sequenced and registered at EMBL and GenBank. For the mapping of quantitative tarits loci (QTL) and eternal recombinant inbred population with 164 F13 lines (MGRI) was developed from a cross between Milyang 23 and Gihobyeo, Korean rice cultivars. After construction of fully saturated RFLP and AFLP map, quantitative traits using MGRI population were analyzed and integrated into the molecular map. Eighty seven loci were determined with 27 QTL characters including yield and yield components on rice chromosomes. Map based cloning was also tried to isolate semi-dwarf (sd-1) gene in rice. A DNA probe, RG 109, the most tightly linked to sd-1 gene was used to screen from bacterial artifical chromosome (BAC) libraries and five over lapping clones presumably containing sd-1 gene were isolated. Rice genetic database including results of biotech reasearch and classical genetics is provided at Korea Rice Genome Server which is accessible with world wide web (www) browser. The server provides rice cDNA sequences and map informations linked with phenotypic images.

• Food Science and Biotechnology
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• v.15 no.2
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• pp.289-297
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• 2006

In this study we examined the changes in weight and dimension, protein and amylose contents, and pasting properties of brown rice flour, as well as the gelatinization properties of starch, from two non-waxy japonica cultivars and one waxy japonica cultivar planted in an experimental field in 2002 under the same fertilizer conditions. The weight of both rough and brown rice increased consistently up to 42 days after flowering (DAF) for the non-waxy rice and to 35 DAF for the waxy rice. The changes in dimension of the brown rice kernel indicated that the length was maximized first, followed by breadth and then thickness. The protein content of the non-waxy rice remained fairly constant, but that of the waxy rice decreased by about 1% after 14 DAF. The amylose content of the non-waxy brown rice flour increased, but that of the waxy brown rice flour decreased during kernel development. As the kernel developed, the peak viscosity of the non-waxy rice flour increased up to 35 DAF, after which it decreased, whereas that of the waxy brown rice flour increased consistently. The gelatinization temperature of starch also increased in the waxy rice during kernel development up to 21 DAF. The gelatinization enthalpy of starch, however, increased in all rice cultivars throughout the kernel development.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.53 no.3
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• pp.320-325
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• 2008

This study was performed to effect of chain length distribution of amylopectin on gelatinization physical properties of cooked rice grains which were analyzed by alkali digestive value (ADV) in six rice cultivars. Those rice cultivars were Hwangumnuribyeo, Ilpumbyeo, Sangjubyeo, Taebongbyeo, Nampyungbyeo, and Dasanbyeo. The ADV values were evenly distributed from 7.0 (Hwangumnuribyeo) to 5.0 (Dasanbyeo). A similar chain length distribution of amylopectin was found in rice cultivars, indicating that DP12 had the highest distribution. Rice cultivars with high ADV value showed higher portion of short chain distribution upto DP15. The surface hardness of cooked rice increased consecutively to Dasanbyeo, Ilpumbyeo, and Hwangumnuribyeo. Among japonica type rice cultivars, the highest overall hardness was observed in Dasanbyeo followed by Hwangumnuribyeo and Ilpumbyeo. Correlation between hardness of rice graim and chain length distribution of amylopectin had the similar inclination to surface hardness of rice grains and overall hardness.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.1
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• pp.14-25
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• 2006

Response of grain yield and milled-rice protein content to nitrogen (N) rates at various growth stages is critical for quantifying real-time and real-amount of applied N requirement for target grain yield and protein content. An experiment including 10 N rate treatments at transplanting, tillering and panicle initiation stages with four rice cultivars in 2003, 6 N treatments with two rice cultivars in 2004 and 2005 was conducted. Increase of N rates at PIS significantly increased both grain yield and milled-rice protein content but increase of N rates at tillering stage significantly increased grain yield but not milledrice protein content. Therefore, high grain yield and low milled-rice protein content would be difficult to obtain only by adjusting N rates at PIS. Internal N use efficiency (INUE) was 60.5 kg grain/kg N accumulation on an average over N treatments, cultivars, and experimental years, showing considerable reduction especially at high shoot N accumulation in the experimental year of low sunshine duration. Milled-rice protein content tended to increase almost linearly with increasing shoot N accumulation, but it revealed big variation even at the same shoot N accumulation at harvest. Milled-rice protein content decreased with increasing INUE. N accumulation in the milled rice increased at an almost constant proportion of 45.5 percent of the shoot N accumulated at harvest, showing slight decresing proportion with the increasing shoot N accumulation.