• KOREAN JOURNAL OF CROP SCIENCE
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• v.25 no.2
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• pp.23-30
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• 1980

Experiments were conducted to know N, P, and K top dressing effects on yield and other agronomic characters of rice plants grown in 5-year differently fertilized soils. Four levels of nitrogen, 0, 1.2, 2.4, and 3.6kg/10a, were applied 32 days before heading in 5-year non-fertilized and PK applied plots. Four levels of P_2 $O_{5}$ and K_2 O of 0, 4, 8 and 12kg/l0a were applied 40 days before heading in 5-year NK and NP applied plots, respectively. 1. Heading was delayed by seven days in 5-year non-fertilized and PK applied plots compared to NK, NP, or NPK applied plots where nitrogen was applied as basal. However, in 5-year non-fertilized and PK applied plots heading was delayed from 1 to 4 days as amounts of nitrogen top dressing increased. Phosphorus and potassium did not affect heading date of rice plants. 2. In 5-year non-fertilized plot grain yield increased as amounts of nitrogen top dressing increased up to 2.4kg/l0a due to both increased number of panicles per hill and spikelets per panicle. However, in 5-year PK applied plot amounts of nitrogen top dressing did not affect grain yield; the number of panicle per hill increased, but the percentage of ripened grains and grain weight tended to decrease as nitrogen levels increase. 3. The number of panicle/maximum tillers ratio in percentage increased markedly as amounts of nitrogen top dressing increased in 5-year non-fertilized and PK applied plots with maximum value of 130% on the basis of maximum tillers at vegetative stage. 4. Top dressing of phosphorus and potassium did not affect yield and other agronomic characters in NK and NP applied plots.

• Korean Journal of Weed Science
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• v.5 no.2
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• pp.131-136
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• 1985

This experiment was conducted to identify the competitive ability of rice against Monochoria vaginalis Presl. and to determine effect of various herbicides on it. Photosynthetic efficiency of rice markedly increased as the density of M. vaginalis increased from 1 to 3 plants per hill. Competition index increased in propotional to an increase of M. vaginalis density while total dry matter of rice decreased in reverse. Significant yield reduction of rice, was observed at the density of M. vaginalis, 2 plants per hill and 37% at 3 plants per hill. Such a yield reduction can be mainly attributed to the decrease of panicle and spikelet number of rice which were greatly affected by competition with M. vaginalis. Regardless of herbicides tested, % inhibition increased remarkably as the concentration of herbicides increased from 1 to 20 ppm. No plant growth was observed in all the herbicides treated with 20 ppm except for butachlor, thiobencarb and bifenox, showing existence of the new promising herbicides to control M. vaginalis among the herbicides tested.

• Korean Journal of Environmental Agriculture
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• v.20 no.2
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• pp.86-92
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• 2001

The current study was conducted to elucidate the optimum density of free-ranging ducks in a rice-duck farming system in terms of effects on duck behavior, and growth and yield of rice plants. Four paddy fields were used for this experiment, with 6, 9, 12 and 15 birds per plot, respectively. Ducklings at eight days of age were free ranged in experimental paddy plots (4.0 a each) on the 9th day after the transplantation of rice plants. Ducks were kept in the plot for seventy days, at which point rice plants reached the earing stage. Foraging, moving, working, resting, diving and pecking behaviors of the ducks were observed two times during the experimental period. Also, rice plant growth and yield according to the density of ducks per plot were examined. The foraging and moving behavior of free-ranging ducks in paddy fields for 12 hours during the daytime tended to be longer in the 12-bird plot, and working behavior was significantly (P<0.01) longer in the 12-bird plot than in the other three plots. The resting behavior was significantly (P<0.01) higher in the 9- and 15-bird plots than in the 12-bird plot. The frequency of moving behavior for 6 hours during the daytime in the 15-bird plot tended to be lower than that in the other three plots, but this difference was not significant. The amount of diving and pecking behavior in the 9-bird plot was significantly (P<0.05) higher than that in the other three plots, and the number of hills pecked tended to be higher with increasing of duck density. From thirty days after ducks were introduced to the paddy fields, the length of rice plants tended to be significantly (P<0.05) shorter in high free-ranging density plots as compared to low free-ranging density plots. The number of tillers per hill was not affected by the free-ranging density. The culm length of rice plants was significantly (P<0.05) shorter in the 12- and 15-bird plots than in the other two plots, however, the duck free-ranging density did not affect panicle length. The dry weight of the root of rice plants was increased with high free-ranging density, but there was no such increase in the top parts of the rice plants. The percent of rice plants badly damaged by free-ranging density tended to be lower in the order of 12-, 9-, 6- and 15-bird plots. The number of ears, ripening grains and crop yield per hill of rice plants in the 12-bird plot were significantly (P<0.05) higher than those of the other three plots. Therefore, the yield of each rice plant per 10 a was significantly increased in the 12-bird plot.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.29 no.4
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• pp.321-327
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• 1984

Grain yield of rice plants grown in outmost first and second rows in paddy field blocked by 50 cm wide levee was averaged 30 percent more than that in center rows, but yield increased percents in border rows were significantly different between varieties. Average border effect through 3 varieties were recognized only in first and second rows from levee, but most vigorous variety, Hangangchal, showed border effect up to fourth rows from levee. Rice plants grown in border rows had more number of panicles per hill and more number of spikelets per panicle. Total dry matter weight and average leaf area of rice plants in border rows differed with those in center rows from 30 to 60 days after transplanting. Early maturing variety showed the difference between border and center rows quickly concerning to total dry matter weight and leaf area. Rice plants grown in border rows showed higher values of CGR, RGR, NAR, and LAR through the growth duration except 1 or 2 growing periods.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.43 no.3
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• pp.161-167
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• 1998

Root and shoot development of two rice (Oryza sativa L.) cultivars with different genetic backgrounds was studied with reference to their relative growth. Tongil type (indica-japonica hybrid) cultivar 'Kuemkangbyeo' and japonica cultivar 'Koshihikari' were grown in $5000^{-1}$ a Wagnar pots under flooded condition. Three plants with roots of both cultivars were taken in every phyllochron through the heading stage to record morphological characteristics of shoot and root system. Compared to Koshihikari, Kuemkangbyeo produced more tillers and had greater shoot weight and leaf area per hill. Length and weight of the root system in both cultivars increased exponentially with time. At the same time, root system development was significantly faster in Kuemkangbyeo than in Koshihikari after the panicle initiation stage. As a result, Kuemkangbyeo has a vigorous root system which consists of larger number of nodal roots compared to Koshihikari. Also, the root length and weight per unit leaf area of Kuemkangbyeo were larger than those of Koshihikari in the later half of growing period, which suggests possible higher physiological activity of the root system of Kuemkangbyeo which is known as a high-yielding cultivar. The relationship between root traits (crown root number, total root length, and root dry weight) and shoot traits (leaf area and leaf+culm dry weight) in both cultivars closely showed allometry until the flag leaf stage.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.43 no.4
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• pp.250-253
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• 1998

Somaclonal variation was observed in the field on doubled haploid plants derived from single pollen of a rice cultivar "Hwaseongbyeo". The variations of seven quantitative traits including plant height and one qualitative trait (pubescence) in 436 lines ($R_2$ generation) were analyzed. The number of lines which fell beyond the boundaries of the 95% confidence intervals of the check variety, Hwaseongbyeo was checked for each quantitative trait, and of those fertility showed the highest variation frequency (85.6%), followed by plant height (77.5%), flag leaf length (66.5%), grains per panicle (42.2%), days to heading (34.5%), panicle length (30.7%) and panicles per hill (22.7%). And the variations of quantitative traits except days to flowering appeared to move in the negative direction compared to "Hwaseongbyeo". Variability within lines was also observed for quantitative and qualitative traits. Twenty-nine $R_2$ lines (7%) segregated for pubescence and 130 $R_2$ lines (30%) showed variation with regard to fertility. This suggests that mutations usually occur before diploidization. Twenty-nine $R_2$ lines representing a wide spectrum of variation were chosen for RAPD analysis. The number of lines showing DNA polymorphism compared to Hwaseongbyeo ranged 0 from to 10 according to the primer used and this seems to indicate that specific loci have highly mutable genomic site.utable genomic site.

• Korean Journal of Soil Science and Fertilizer
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• v.32 no.3
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• pp.295-303
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• 1999

An experiment was conducted to evaluate the possibility of using basic oxygen furnace (BOF) slag as a soil conditioner in rice paddy field. In 1997, rice (Oryza sativa B. cv. Dongjinbyeo) crop was cultivated under different application rates of BOF slag at three different places, Inandong Sunchon city, Youjunglee Bosung province, and Nampyung Najoo city. In each paddy field, five treatments, four application rate of BOF slag (0, 4, 8, $12Mg\;ha^{-1}$) and one application rate of lime ($2Mg\;ha^{-1}$) were tried with three replications. Plant height, number of tillers per hill, leaf area per hill, leaf dry weight, calm dry weight or shoot dry weight per hill were measured five times at the interval of seven days. Chemical contents of rice plants and soil were also measured at the same sampling date Yield were estimated by harvesting $6.6m^2$ per experimental unit and yield components were measured by sampling 10 plants per experimental unit at the harvest date. Application of BOF slag hardly affected contents of soil organic matter, available phosphate and potassium in soil. Soil pH and contents of Ca, Mg, Fe and $SiO_2$ enhanced as BOF slag rate increased. Enhancement of soil pH by ROF slag treatment appeared to be closely related with increase in soil Ca content. Application tate of $2Mg\;ha^{-1}$ of lime showed almost the same effect, in increase of soil Ca content as application rate of $4{\sim}8Mg\;ha^{-1}$ of BOF slag, Fe content in soil decreased sharply as time passed after slag treatment and stabilized more or less at the later sampling date. Contents of inorganic matter in plant such as total nitrogen, phosphate, potassium and Mg were not affected by BOF slag treatment. However, contents of Ca, Fe, and $SiO_2$ in plants increased as slag rate became higher. The growth of rice plants with BOF slag treatment was more or less slower but continued persistently up to the later growth stage, so that growth of plants with BOF slag treatment was almost the same nr even greater than that of control or lime treatment. However, BOF slag rate of $12Mg\;ha^{-1}$ seemed to be too high because all the measurements of plant, growth at this rate showed lower values than those of other treatments at all the sampling dates. Treatments of BOF slag $4Mg\;ha^{-1}$ or $8Mg\;ha^{-1}$ showed higher rough rice yield than other treatments, so that the optimum BOF slag ratein rice paddy field seemed to be in the rage of $4{\sim}8Mg\;ha^{-1}$.

• Proceedings of the Korean Society of Crop Science Conference
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• 2004.04a
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• pp.144-145
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• 2004

• KOREAN JOURNAL OF CROP SCIENCE
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• v.44 no.2
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• pp.143-148
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• 1999

Soil moisture condition is an important limiting factor in growth and yield in rice culture. The purpose of this study was to compare the influence on the growth, yield and Quality of rice subjected to soil moisture stress (SMS) at different growth stages. Ajaponica rice cultivar, Dongjinbyeo, was cultured under flooded conditions in a plastic container filled with silty loam soil. The container was subjected to SMS until the initial wilting point (IWP) coincided with about 10% in soil moisture content and about-200 kPa in soil matric potential, and was then irrigated again, at 6 and 5 of main growth stage in 1996 and 1997, respectively. At maturity, the plant height, tiller number, leaf area and top dry weight were decreased more in SMS treatments at the early stage than the late stage. The averaged yield index of SMS to control in both years was lowest at meiosis (62.5%), which primarily resulted from lower percent ripened grain and 1,000 grain weight, and second＇ reduced the spikelet number per panicle and panicle number per hill, and followed at tillering stage (68.5%) which resulted from the lower production in tiller number and top dry matter during and after SMS treatment. The percent-age of read rice in SMS plants varied with the treatment stage as order of lower at meiosis (44.0%), heading (53.9%), panicle initiation (70.1%), tillering (72.1%), ripening (75.8%) and 5 days after transplanting (DAT) (79.0%). Protein content in brown rice was slightly larger in SMS at late growth stage than the control, while the contents of fat and ash differed very little between SMS and control. Contents of Mg and K and Mg/K in brown rice with SMS were lower at some treatment stages such as at ripening or panicle initiation.

• Korean Journal of Breeding Science
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• v.40 no.3
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• pp.223-227
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• 2008

In rice, tillering is an important trait determining yield. To study tillering at the agricultural and molecular aspects, we have examined a spontaneous rice mutant that showed reduction in the number of culms. The mutant was derived from a $F^6$ line of the cross of Junambyeo*4 / IR72. It could produce, on average, 4 tillers per hill in the paddy field while wild-type plants usually have 15. Except the reduced culm numbers, they also show pale green phenotypes. The phenotypes of this mutant were co-segregated as the monogenic Mendelian ratio (${\chi}^b=0.002$, p=0.969). In order to locate a gene responsible for the rcn phenotype, the mutant with the japonica genetic background was crossed with Milyang21 of the indica background. Bulked segregant analysis was used for rapid determination of chromosomal location. Three SSR markers (RM551, RM8213, and RM16467) on chromosome 4 were genetically associated with the mutant phenotype. Each of the 217 $F_2$ plants was genotyped with simple sequence length polymorphisms. The data showed that RM16572 on chromosome 4 was the closest marker that showed perfect co-segregation among the $F_2$ population. We suggest the new rcn gene studied here name as $rcn10^t$ because there was no report which exhibit a rcn phenotype with a pleiotropic effect of pale green (chlorophyll deficiency), and mapped at same position on chromosome 4.