• Asian-Australasian Journal of Animal Sciences
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• v.29 no.10
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• pp.1470-1476
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• 2016

Octacosanol, which has prominent physiological activities and functions, has been recognized as a potential growth promoter in animals. A total of 392 1-d-old male Arbor Acres broiler chicks with similar body weight were randomly distributed into four dietary groups of seven replicates with 14 birds each supplemented with 0, 12, 24, or 36 mg octacosanol (extracted from rice bran, purity >92%)/kg feed. The feeding trial lasted for six weeks and was divided into the starter (day 1 to 21) and the grower (day 22 to 42) phases. The results showed that the feed conversion ratio (FCR) was significantly improved in broilers fed a diet containing 24 mg/kg octacosanol compared with those fed the control diet in the overall phase (day 1 to 42, p = 0.042). The average daily gain and FCR both showed linear effects in response to dietary supplementation of octacosanol during the overall phase (p = 0.031 and 0.018, respectively). Broilers fed with 24 or 36 mg/kg octacosanol diet showed a higher eviscerated yield, which increased by 5.88% and 4.26% respectively, than those fed the control diet (p = 0.030). The breast muscle yield of broilers fed with 24 mg/kg octacosanol diet increased significantly by 12.15% compared with those fed the control diet (p = 0.047). Eviscerated and breast muscle yield increased linearly with the increase in dietary octacosanol supplementation (p = 0.013 and 0.021, respectively). Broilers fed with 24 or 36 mg/kg octacosanol diet had a greater (p = 0.021) $pH_{45min}$ value in the breast muscle, which was maintained linearly in response to dietary octacosanol supplementation (p = 0.003). There was a significant decrease (p = 0.007) in drip loss value between the octacosanol-added and the control groups. The drip loss showed linear (p = 0.004) and quadratic (p = 0.041) responses with dietary supplementation of octacosanol. These studies indicate that octacosanol is a potentially effective and safe feed additive which may improve feed efficiency and meat quality, and increase eviscerated and breast muscle yield, in broiler chicks. Dietary supplementation of octacosanol at 24 mg/kg diet is regarded as the recommended dosage in the broilers' diet.

• Korean Journal of Environmental Agriculture
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• v.1 no.2
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• pp.123-128
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• 1982

This study was carried out to investigate the effect of ozone gas on paddy rice at the different growth stage. Seokwang variety of rice plant was exposed to 0.5 ppm ozone gas for 4 hours at rooting, maximum tillering, ear formation and heading stages. after ozone gas fumigation, damage symptom, percentage of destroyed leaf, chlorophyll content and peroxidase activity of rice plant were observed. The results obtained are as follows. 1) Typical symptom of ozone gas damage appeared greyish or reddish brown subtle spots within rice leaf vein. 2) Yield loss by ozone gas exposure at different growth stage was in the order of maximum tillering stage>rooting stage>ear formation stage>heading stage. 3) Chlorophyll damage and leaf destruction was the highest at maximum tillering stage, while damage of leaf and chlorophyll were not found at heading stage. 4) The damage by ozone gas fumigation was higher at the growth stage with higher N content in plant, and N content was decreased after ozone gas exposure.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.61 no.4
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• pp.251-256
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• 2016

The increase in carbon stock and sustainability of crop production are the main challenges in agricultural fields relevant to climate change. Methane is the most important greenhouse gas emitted from paddy fields. This study was conducted to investigate the effects of tillage and cultivation methods on methane emissions in rice production in 2014 and 2015. Different combinations of tillage and cultivation were implemented, including conventional tillage-transplanting (T-T), tillage-wet hill seeding (T-W), minimum tillage-dry seeding (MT-D), and no-tillage-dry seeding (NT-D). The amount of methane emitted was the highest in T-T treatment. In MT-D and NT-D treatments, methane emissions were significantly decreased by 77%, compared with that in T-T treatment. Conversely, the soil total carbon (STC) content was higher in MT-D and NT-D plots than in tillage plots. In both years, methane emissions were highly correlated with the dry weight of rice ($R^2=0.62{\sim}0.96$), although the cumulative emissions during the rice growing period was higher in 2014 than in 2015. T-T treatment showed the highest $R^2$ (0.93) among the four treatments. Rice grain yields did not significantly differ with the tillage and cultivation methods used. These results suggest that NT-D practice in rice production could reduce the methane emissions and increase the STC content without loss in grain yield.

• Korean journal of applied entomology
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• v.22 no.4 s.57
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• pp.244-250
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• 1983

This study was carried out to analyst the damage due to the brown planthopper, Nilapalvata lugens Stal, at different stages(maximum tillering, booting, heading, and milking) of rice. The results are as follows: The population density of the migrating and the first generations of the brown planthoppers seemed not to be large enough to cause significant effects on the plant height and the number of tillers, while the second and the third generations caused significant reduction in 1000 grain weight(Yl) and the filled grain percentage$(Y_2)$. They were very closely related to the population density(X) of tile second generation of the BPH; $$Y1(g)=25.602-0.0213X(r=-0.5205^{**})$$ $$Y2(\%)=76.97-0.1370X(r=-0.4820^{**})$$ The relationship between rice yield (Yg) and the accumulated total density (X) of BPH per hill by the time of harvest; $$Y(g)=24.694-0.0576X(r=-0.6959^{**})$$ Since the source of the outbreak BPH is the first generation, it nay conclude that the detailed information on the population status of the first generation; density, age components, ratio of the brachypterous form, are very important in relation to management of the pest.

• The Korean Journal of Pesticide Science
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• v.15 no.4
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• pp.545-572
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• 2011

The genetic diagnosis methods by RT-PCR and Virion capture (VC)/RT-PCR against Rice stripe virus (RSV) were developed. Three diagnosis methods of seedling test, ELISA and RT-PCR were compared in virus detection sensitivity (VDS) for RSV. The VDS of ELISA for RSV viruliferous small brown plant hopper (SBPH) was higher with 40.5% than that of seedling test. The VDS of RT-PCR was higher with 21% than that of ELISA. The VDS of ELISA and VC/RT-PCR was same with 9.2% in average on the SBPH collected from fields at the areas of Gimpo, Pyungtaeg and Sihueng, Gyeonggi province in 2009. The specific primers of RSV for SBPH and rice plant were developed for the diagnosis by Real time PCR. The RQ value of Real time PCR for the viruliferous and non viruliferous SBPH was 1 for 50 heads of non viruliferous SBPH, 96.5 for 50 heads of viruliferous SBPH, 23.1 for 10 heads of viruliferous SBPH + 40 heads of non viruliferous SBPH, and 75.6 for 30 heads of viruliferous SBPH + 20 heads of non viruliferous SBPH. The RQ value was increased positively by the ratio of viruliferous SBPH. Full sequences of 4 genomes of RSV RNA1, RNA2, RNA3 and RNA4 were analysed for the 13 RSV isolates from rice plants collected from different areas. Genetic relationships among the RSV isolates of Korea, Japan and China were classified as China + Korea, and China + Korea + Japan by phylogenetic analysis for RSV RNA1 and RNA2. In case of RNA3 involved in pathogenicity, genetic relationship of RSV among the three countries was grouped into 3 as China, China + Korea, and Korea + Japan. According to the genetic relationships in RSV RNA4, RSV isolates were grouped into 4 as China, Korea, China + Korea + Japan, and Korea + Japan. Viruliferous insect rate (VIR) of RSV in average increased in each year from 2008 to 2010, and the rates were 4.3%, 6.1%, and 7.2%, respectively, at the 28 major rice production areas in 7 provinces including Gyeonggido. The highest VIR in each year was 11.3% of Gyeonggido in 2008, 20.1% of Jellanamdo in 2009 and 14.2% of Chungcheongbukdo in 2010. The highest VIR depending upon the investigated areas was 22.1% at Buan of Jellabukdo in 2008, 36% at Wando and Jindo of Jellanamdo in 2009, and 30.0% at Boeun of Chungcheongbukdo in 2010. Average population density (APD) of overwintered SBPH was 13.1 heads in 2008, 13.9 heads in 2009 and 5.6 heads in 2010. The highest APD was 39.1 and 60.4 heads at Buan of Jellabukdo in 2008 and 2009, respectively, and 14.0 heads at Pyungtaeg of Gyeonggido. The acreage of RSV occurred fields was 869 ha in the western and southern parts, mainly at Jindo and Wando areas, of Jellanamdo in 2008. In 2009, RSV occurred in the acreage of 21,541 ha covered whole country, especially, partial and whole plant death were occurred with infection rate of 55.2% at 3,025 plots in 53 Li, 39 Eup/Myun, 19 Si/Gun of Gyeonggido, Incheonsi, Chungcheongnamdo, Jeollabukdo and Jeollanamdo. Seasonal development of overwintered SBPH was investigated at Buan, Jeollabukdo, and Jindo, Jeollanamdo for 3 years from 2008. Most SBPH developed to the 3rd and 4th instar on the periods of May 20 to June 10, and they developed to the adult stage for the 1st generation on Mid and Late June. In 2009, all SBPH trapped by sky net trap were adult on May 31 to June 1 at Mid-western aeas of Taean, Seosan and Buan, and South-western areas of Sinan and Jindo. The population density of adult SBPH was 963 heads at Taean, 919 at Seocheon and 819 at Sinan area. The origin of these higher population of adult SBPH were verified from the population of non-overwintered SBPH but immigrant SBPH. From Mid May to Mid June in 2010, adult SBPH could not be counted as immigrant insects by sky net trap. The variation of RSV VIR was high with 2.1% to 9.5% for immigrant adult SBPH trapped by sky net trap at Hongsung of Chungcheongbukdo, Buan of Jeollabukdo and so forth in 2009. The highest VIR for the immigrant adult SBPH was 9.5% at Boryung of Chungcheongnamdo, followed by 7.9% at Hongsung of Chungcheongnamdo, 6.5% at Younggwang of Jeollanamdo, and 6.4% at Taean of Cheongcheongnamdo. The infection rate of RSV on rice plants induced by the immigrant adult SBPH cultivated near sky net trap after about 10 days from immigration on June 12 in 2009 was 84.6% at Taean, 65.4% at Buan and 92.9% at Jindo, and 81% in average through genetic diagnosis of RT-PCR. Barley known as a overwintering host plant of RSV had very low infection rate of 0.2% from 530 specimens collected at 10 areas covering whole country including Pyungtaeg of Gyeonggido. Twenty nine plant species were newly recorded as natural hosts of RSV. In winter annual plant species, 11 plants including Vulpia myuros showed RSV infection rate of 24.9%. The plant species in summer annual ecotype were 13 including Digitaria ciliaris with 44.9%, Echinochloa crusgalli var. echinata with 95.2% and Setaria faberi with 65.5% in infection rate of RSV. Five perennial plants including Miscanths sacchariflorus with infection rate of 33.3% were recorded as hosts of RSV. Rice cultivars, 8 susceptible cultivars including Donggin1 and 17 resistant ones including Samgwang, were screened in field conditions at 3 different areas of Buan, Iksan and Ginje in 2009. All the susceptible cultivars were showed typical symptom of mosaic and wilt. In 17 genetic resistant cultivar, 12 cultivars were susceptible, however, 5 cultivars were field-resistant plus genetic resistant to RSV as non symptom expression. When RSV was artificially inoculated at seedling stage to 4 cultivars known as genetic resistant and 3 cultivars known as genetic susceptible, the symptom expression in resistant cultivars was lower as 19.3% in average than that of 53.3% in susceptible ones. In comparison of symptom expression rate and viral infection rate using resistant Nampyung and susceptible Heugnam cultivars by artificial inoculation of RSV at seedling stage, the symptom expression of Heugnam was higher as 28% than 12% of Nampyung. However, virion infection of resistant Nampyung cultivar was higher as 12% reversely than 85% of susceptible Heugnam. Yield loss of rice was investigated by the artificial inoculation of RSV at the seedling stage of resistant cultivars of Nampyung and Onnuri, and susceptible cultivars of Donggin1 and Ungwang for 3 years from 2008. The average yield per plant was 7.8 g, 8.5 g and 13.8 g on rice plants inoculated at seedling stage, tillering stage and maximum tillering stage, respectively. The yield loss rate was increased by earlier infection of RSV with 51% at seedling stage, 46% at tillering stage and 13% at maximum tillering stage. In resistant rice cultivars, there was no statistically significant relation between infection time and yield loss. In natural fields on susceptible rice cultivar of Ungwang at Taean and Jindo areas in 2009, the yield loss rate was increased with same tendency to the infection hill rate having the corelation coefficient of 0.94 when the viral infection was over 23.4%.

• Korean Journal of Soil Science and Fertilizer
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• v.37 no.2
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• pp.97-103
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• 2004

This study was performed to assess the influences of liquid pig manure (LPM) on the rice growth and nutrient behavior in soil under two different drainage comditions. Soils of paddy field were Jeonbuk and Gangseo series, and drainage conditions of the soils were imperfectly drained and moderate well drained, respectively, Application of LPM was based on nitrogen, and the treatments included 110 (LPM-N100%), 165 (LPM-N150%) and $220(LPM-N200%)kg\;N\;ha^{-1}$. In the LPM-N150% treatment, rice growth and yield were similar to the control treatment of conventional chemical fertilizer application. Rice yield of moderately well drainedfield were 3-11% higher than that of imperfectly drained field. Loss of nitrogen through $NH_3$ gas after application of LPM was higher in no plowing than in rotary plowing field. Losses of $NO_3-N$, $NH_4-N$, $SO_4$, Ca and K through runoff water were increased as the amount of LPM application increased. Losses of $NO_3-N$ and K through infiltration were higher in LPM-150% and LPM-N200% treatments compared to the chemical fertilizer treatment. Contents of $NO_3-N$ in infiltration water measured from trasplanting to tillering stage was higher at the moderately well drained condition than imperfectly drained condition. Contents of $P_2O_5$ and K in soil were accumulated by application of LPM compared to the chemical fertilizer plot.

• Korean Journal of Environmental Agriculture
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• v.24 no.2
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• pp.180-184
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• 2005

This study was peformed to assess environmental effect through rice culture with sewage irrigation using Iksan stream water from 2002 to 2003. Contents of $NH_4-N$ in irrigation water keep up one day at the tillering stage and panicle formation stage were decreased 40% and 52% respectively, but that of continued 4 days was decreased $88%{\sim}98%$. The $NH_4-N\;and\;NO_3-N$ in run off by reduction 50% fertilization were more decreased 17% and 44% respectively, than those of conventional fertilization level. Amount of K and $NO_3-N$ loss in infiltration water were more decreased 18% and 4% respectively, those of than conventional fertilization level. The Cu and Pb contents in soil of after experiment were slightly increased but other heavy metals were not accumulated. The rice yield by reduction 50% fertilization level was not significant compare with conventional fertilization level but head rice rate was increased.

• The Plant Pathology Journal
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• v.36 no.4
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• pp.305-313
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• 2020

Host shifting and host expansion of fungal plant pathogens increases the rate of emergence of new pathogens and the incidence of disease in various crops, which threaten global food security. Magnaporthe species cause serious disease in rice, namely rice blast disease, as well as in many alternative hosts, including wheat, barley, and millet. A severe outbreak of wheat blast due to Magnaporthe oryzae occurred recently in Bangladesh, after the fungus was introduced from South America, causing great loss of yield. This outbreak of wheat blast is of growing concern, because it might spread to adjacent wheat-producing areas. Therefore, it is important to understand the host range and population structure of M. oryzae and related species for determining the evolutionary relationships among Magnaporthe species and for managing blast disease in the field. Here, we collected isolates of M. oryzae and related species from various Poaceae species, including crops and weeds surrounding rice fields, in Korea and determined their phylogenetic relationships and host species specificity. Internal transcribed spacer-mediated phylogenetic analysis revealed that M. oryzae and related species are classified into four groups primarily including isolates from rice, crabgrass, millet and tall fescue. Based on pathogenicity assays, M. oryzae and related species can infect different Poaceae hosts and move among hosts, suggesting the potential for host shifting and host expansion in nature. These results provide important information on the diversification of M. oryzae and related species with a broad range of Poaceae as hosts in crop fields.

• Molecules and Cells
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• v.42 no.12
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• pp.858-868
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• 2019

Shoot branching is an essential agronomic trait that impacts on plant architecture and yield. Shoot branching is determined by two independent steps: axillary meristem formation and axillary bud outgrowth. Although several genes and regulatory mechanism have been studied with respect to shoot branching, the roles of chromatin-remodeling factors in the developmental process have not been reported in rice. We previously identified a chromatin-remodeling factor OsVIL2 that controls the trimethylation of histone H3 lysine 27 (H3K27me3) at target genes. In this study, we report that loss-of-function mutants in OsVIL2 showed a phenotype of reduced tiller number in rice. The reduction was due to a defect in axillary bud (tiller) outgrowth rather than axillary meristem initiation. Analysis of the expression patterns of the tiller-related genes revealed that expression of OsTB1, which is a negative regulator of bud outgrowth, was increased in osvil2 mutants. Chromatin immunoprecipitation assays showed that OsVIL2 binds to the promoter region of OsTB1 chromatin in wild-type rice, but the binding was not observed in osvil2 mutants. Tiller number of double mutant osvil2 ostb1 was similar to that of ostb1, suggesting that osvil2 is epistatic to ostb1. These observations indicate that OsVIL2 suppresses OsTB1 expression by chromatin modification, thereby inducing bud outgrowth.

• Korean Journal of Breeding Science
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• v.41 no.4
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• pp.488-495
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• 2009

In recent years, an increasing amount of research has been conducted on the yield loss of soybean crop caused by Riptortus clavatus, a serious pest of legumes. The objective of this study were to examine crop damage caused by various population densities of R. clavatus and determine the association of unique growth and seed characteristics with crop damage rate in conventional soybean fields. Major growth responses to R. clavatus were examined. The cultivars that were not as seriously damaged by R. clavatus were Pungsannamulkong, Sobaegknamulkong, Duyoukong, and Sinpaldal 2, but Myeongjunamulkong, Mallikong, and Hwangkeumkong were significantly (P<0.05) damaged. The rate of seed damage caused by R. clavatus was 8.2% in a group of brown colored pubescence, while the rate was 13.0% in a group of the gray colored. Crop damage by R. clavatus clearly more reduced in cultivars with dark hilum colors including dark brown, brown, and grayish brown than those with yellow hilum colors. Concerning pod colors, crop damage was less significant in cultivars with dark brown pod color than with the light brown. Cultivars with short pod length (4.0-4.5 cm) at full seed (R6) stage showed lower seed damage rates by R. clavatus than those with long pod length (>5.6 cm). Therefore, characteristics of hilum, pod, pubescence colors, and pod length were significantly related and linked to the cultivar resistance to R. clavatus.