• Research in Plant Disease
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• v.16 no.2
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• pp.183-190
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• 2010

During the period from 1999 to 2008, we surveyed the major diseases incidence of rice in Korea. Leaf blast showed 0.85% of the diseased leaf area in 2000 and then consistently decreased to 0.02% by 2008. However, panicle blast irregularly appeared by the years depending on weather conditions for disease development from heading to milk stage of rice. Diseased lesion height of sheath blight had the lowest (10.1%) incidence in 2001 and the highest (21.4%) incidence in 2007. A negative corelation ($r=-0.88^*$) was measured between diseased lesion height of sheat blight and sunshine hours from mid- to late August. In Chunbuk, Gyeongbuk, and Gyeongnam provinces, brown spot occurrence declined since 2001, however, in Chungnam, Jeonbuk, and Jeonnam provinces, it increased since 2005. False smut drastically decreased after showing the highest incidence of 7.59% in panicles in 2000. The correlation coefficient between diseased panicles of false smut and rainfall during the late August was calculated as $0.94^{**}$. Bacterial leaf blight severely increased in the chronically infested fields in Jeonnam, Jeonbuk, Gyeongnam, and Chungnam province since 2003.

• Korean Journal of Organic Agriculture
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• v.25 no.2
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• pp.475-487
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• 2017

The aim of this study was to solve the problem of yield loss causing the lag of fertilizer efficiency after tiller stage, being originated by applying mixed expeller cake fertilizer on three day before rice transplanting in organic rice farmers. The mineralization degree of $NH_4-N$ of the mixed expeller cake fertilizer was increased until 7 weeks at flooding condition, and so did $NO_3-N$ until 5 weeks at non-flooding condition. The mineralization rate of nitrogen in paddy soil on 20 days before rice transplanting was the highest by 0.85% on 20 days before the transplanting treatment. The properties of yields during the harvest period have no difference with application time of the mixed expeller cake fertilizer, except soil organic matter. The plan length, culm length and panicle length were the longest on 20 days before rice transplanting. Also, the number of tiller, ripening rat and 1,000 grain weight were the highest on 20 days before rice transplanting, and thereby the yield of white rice were increasing by 9% on 20 days before rice transplanting compared with that of 3 days before rice transplanting. The whiteness values of the rice and amylose content made no difference, but the value of protein and palatability were the same between 20 days and 30 days treatment. In the conclusion, the relationship between rice yield, its quality and application time of the mixed expeller cake fertilizer has showed that the suitable time of applying it reveals 21.3 days before rice transplanting.

• Journal of Wetlands Research
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• v.16 no.4
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• pp.363-370
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• 2014

We grew seedlings of Saechucheongbyeo and Odaebyeo of rice cultivars that are cultivated dominantly in the northern and middle regions of Korea under control(ambient condition), ambient $CO_2$ concentration+elevated temperature, and elevated $CO_2$ concentration+elevated temperature in order to study how growth responses and crop yield of major rice of Korea change as the global warming proceeds and compared the results. Aboveground biomass, belowground biomass, total biomass, and panicles weight per individual and ripended grain rate of cv. Saechucheongbyeo were the highest under control, but those of cv. Odaebyeo were the highest under elevated $CO_2$ concentration+elevated temperature. There was no difference in the number of panicles per individual of cv. Saechucheongbyeo and cv. Odaebyeo in these experiments. There was no difference in the number of grains per panicle of cv. Saechucheongbyeo among three environmental gradients, but that of cv. Odaebyeo was the highest under elevated $CO_2$ concentration+elevated temperature. Weight of a grain of cv. Saechucheongbyeo was highest under elevated $CO_2$ concentration+elevated temperature, but that of cv. Odaebyeo was the higher under ambient $CO_2$ concentration+elevated temperature and elevated $CO_2$ concentration+elevated temperature. Thus, if global warming continues in Korea, selection of rice cultivation varieties must be chosen carefully for commendation.

• Korean Journal of Agricultural and Forest Meteorology
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• v.8 no.3
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• pp.125-131
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• 2006

This survey was carried out to investigate the characteristics of low temperature injury in rice plants at a southwestern alpine area of Korea in 2003. During vegetative, reproductive, and ripening stage in a southwestern alpine area, mean air temperature was lower by 0.4, 3.1 and $1.7^{\circ}C$, respectively, as compared to those of a normal year, Minimum air temperature during the reproductive and ripening stage was lower by 2.6 and $1.7^{\circ}C$, respectively, as compared to those of a normal year, Sunshine hours during vegetative, reproductive, and ripening stage were lower by 40.6, 81.3 and 8.4 hours, respectively, than those of a normal year. Spikelet-sterility type cold injury occurred from the latter part of June to the middle of July, which is from panicle formation stage to meiosis stage, at temperatures less than $17^{\circ}C$. Spikelet sterility under normal transplanting (May 20) ranged from 16 to 58%, which was lower than that under early transplanting in the latter part of April (29 to 83%). The total area impacted by cold damage was 2,723ha in Namwon, 510ha in Sunchang, 300ha in Jinan, 250ha in Muju, and 210ha in Jangsu. Average spiklet sterility in these regions was 44%. Rice cultivars Odaebyeo, Unbongbyeo, and Jinbubyeo showed greater tolerance to low temperature than CV, Chugwangbyeo.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.1
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• pp.16-21
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• 2005

This study was conducted to establish the elaborate nitrogen fertilization method to enhance N use efficiency in direct-seeded rice on flooded paddy. The nitrogen uptake by rice plants was insignificant until 25 days after seeding, and increased gradually thereafter. During this early growth stage, rice plants absorbed only the $4\%$ of basal applied N, while the $45\%$ of N fertilizer remained in the paddy soil. The absorption of basal N by rice plants was almost completed at 46 days after application. Nitrogen top-dressed at 5-leaf stage was well matched to crop nutrient demand, so it could be absorbed so actively in 8days after application. As a result, we could cut down the amount of N fertilizer to $36\%$ of the basal N level without significant difference in yield. Plant recoveries of fertilizer $^{15}N$ applied with different application timings were $7.8\%$ for basal, $9.4\%$ for 5-leaf stage, $17.1\%$ for tillering stage, and $23.4\%$ for panicle initiation stage, respectively. When urea was applied with nitrogen fertilization practice based on basal incorporation (BN), plant recovery of $^{15}N$ at harvest was $31.0\%$, which was originated from $13.7\%$ for grain, and $21.3\%$ of the fertilizer $^{15}N$ remained in the soil, and the rest could be uncounted. Plant recovery of fertilizer $^{15}N$ applied with nitrogen fertilization practice based on topdressing at 5-leaf stage (TN), where N rate was reduced by $18\%$ compared with BN, was $35.1\%$ (grain $15.6\%$), and $19.9\%$ of the fertilizer $^{15}N$ remained in the soil, and the rest could be uncounted. TN showed a higher $^{15}N$ recovery than BN because it was to apply N fertilizer at a time to well meet the demand of rice plant direct-seeded on flooded paddy. We concluded that TN would be the nitrogen fertilization method to enhance N use efficiency in direct-seeded rice on flooded paddy.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.40 no.3
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• pp.382-390
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• 1995

To compare the rice yield and grain quality characteristics between mature(MPF) and reclaimed paddy field(RPF), grain yield and its components, some physicochemical properties of rice grain and palatability of cooked rice were investigated for Dongjinbyeo grown at three different locations of mature and reclaimed paddy field, respectively, in south western part of Korea. Variation of culm length in mature paddy area was larger than that in reclaimed saline area. Panicle number per m$^2$ in RPF was more then that in MPF but grain number per m$^2$, filled grain ratio and 1, 000-grain weight in RPF were lower than those in MPT. Average yield of milled rice in RPF was 12% lower than that in MPF (5.l1t /ha). Daejeon showed the highest yielding among MPF and Yeongam reveald the highest grain production among RPF. RPF rices had slightly higher carbohydrate content and alkali digestibility but lower protein, fat and amylose content compared with MPF rices. RPF rices also exhibited higher mineral contents, Mg/K ratio, peak and hot viscosity compared with MPF rices. RPF rice showed slightly poor apparent grain quality but a little better eating quality of cooked rice compared with MPF rice.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.28 no.4
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• pp.419-424
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• 1983

Tensile strength and shattering losses of rice grains in a binder harvest and in a free falling test were examined. Indica$\times$Japonica varieties, Milyang 23, Hangangchal, and Taebaek, and a Japonica variety, Jinheung were used for this study. The average tensile strength varied with varieties, showing 0.743N (Newton) in Milyang 23, 1.078N in Hangangchal, 1.573 N in Taebaek, and 1.775 N in Jinheung. Extrapolation of the average tensile strength for the zero field loss of grain indicated about 1.7 N. Moisture content of straw at the cutting position in a binder harvest was 76.0 to 86.7% in culm and 76.7 to 77.8% in leaf sheath. The percent loss of grains occurring in binder barvest in the field was equivalent to the degree of shattering in the panicle-falling test onto the concrete floor at the height of about 40cm. The grain shattering (Y) was closely related to the impulse (X), the change in momentum: Y=-25.73+4958.4X, ($r^2$=0.987) for Milyang 23, Y=-12.97+2258.3X, ($r^2$=0.979) for Hanagangchal, Y=-5.24+840.4X, ($r^2$ =0.976) for Taebaek. The tensile strengths of grains and their variance varied singnificantly yearly even in the same variety. The magnitude of year-variance was somewhat smaller for the easily shattering variety.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.53 no.3
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• pp.239-243
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• 2008

This experiment was carried out to elucidate the appropriate split application method of nitrogen fertilizer in infant rice seedlings which show poor seedling growth resulted from extended seedling nursery duration more than 12 days. The 16 day-old infant rice seedling (DOIRS) showed poor seedling growth than 8 day-old seedling. Early growth of transplanted 16 DOIRS was poor, compared with that of transplanted 8 DOIRS. However, the poor plant growth estimated by plant height, tiller number, and the number of newly developed roots was compensated by 70-0-30% (basaltillering-panicle initiation) of nitrogen split application. In 70-0-30% plots among split nitrogen application methods, tiller number, biomass, and leaf area at heading stage of rice showed the highest values. Sixteen DOIRS plots showed lower grain filling and 1000-grain weight, resulted in lower yield of rice than 8 DOIRS plots in the same nitrogen split application. However the lower yield in 16 DOIRS plots was recovered by 70-0-30% of nitrogen split application method to a similar level in 8 DOIRS plots in which nitrogen was split applied by 40-30-30%.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.37 no.2
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• pp.198-208
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• 1992

Recently, a nursery mat made from rock wool has realized transplanting of the younger seedlings with the ordinary transplanting machines for Chibyo and Chubyo(3 and 4～5 leaved seedling, respectively). The seedlings defined as the 'Nyubyo' or 'Nursling seedlings' became possible to achieve economic profits from the reduction in both working time and costs. It being widely noticed as a strategy to solve the difficulties in current rice cultivation. The nursling seedlings are 1.4 to 2.5 leaves and height at 4.5 to 7cm, grown 4 to 7 days after seeding. They maintain still up to 50 to 80% of their nutrients in the endosperm, and can grow by using only their own nutrients for a certain period of time after transplanting. Nursling seedlings take 2 days in the nursery chamber at 32$^{\circ}C$ after seeding, and 2 days in the greening house at $25^{\circ}C$. This is only 4 days, all together, to make the nursling seedlings of 1.5 leaves which are ready for transplanting. Watering is only needed once at the sowing time. It only takes 1 or 2 waterings even to raise a seedlings for a period of 7 days. The number of nursery boxes can be reduced because it is possible to sow more densely(220 to 240g per box), thus it only needs seedlings of 15 to 16 boxes per 10 a which leads to a reduction in facilities and space needed. Temperature during the nursery period can be artificially adjusted more precisely which may lead to the prevention of temperature stress. The nursling seedlings can root rapid by because the crown roots from the coleoptile node begin to emerge immediately after transplanting. They show strong resistance to low temperature (12$^{\circ}C$) and deep-planting. There is no danger in the rooting of the seedlings even if half of their height is buried into the soil. Moreover, it can root at a rate of up to 65 to 80% even if the full height of the seedlings is buried. They show also strong resistance to submergence (10～15cm). The nursling seedlings tend to grow by producing tillers from lower nodes. It is therefore, necessary to control to keep the proper numbers of tillers per unit area. They have no fear in the delay of heading and their yield components can be so well balanced that the same level of yield was achieved with the nursling seedlings compared to that with Chibyo. It was further suggested that if the surplus tillers can be avoided by such cultivation practices, the number of grain per panicle can be kept greater and higher yield can be realized. Practical experiments with the nursling seedlings conducted in 1989 and 1990 by farmers in various areas showed exciting results. The nursling seedlings will become widely spread, or at least occupy an important position in Japanese and also in Korean rice cultivation techniques.tivation techniques.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.33 no.4
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• pp.336-342
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• 1988

An experiment was carried out to know the effects of paclobutrazol application time on the lodging related traits and yield of a rice variety. Seomjinbyeo, at two nitrogen leveles. Paclobutrazol (3kg 10a of 0.6% G) was applied 43, 33, 23, and 13 days before heading (DBH) and lodging related traits were observed 10, 20, 30, and 40 days after heading (DAH). Earlier applications of paclobutrazol reduced the length of lower internodes and later applications reduced the upper internodes. Culm length tended to decrease as time of paclobutrazol application delayed. Although lodging was not occurred in all plots. lodging index of paclobutrazol treated plots was lower than that of control and increased with maturity, Fresh weight of shoot increased up to 30 DAH and then decreased. Both fresh weight and breaking strength did not show consistent tendency with time of paclobutrazol application and observation. Direct effect of shoot fresh weight contributing to lodging index decreased with maturity. but that of breaking strength and culm length was similar during the ripening stages. Direct effect contributing to lodging index was greater in the order of breaking strength culm length. and fresh weight 40 DAH. Starch content of culm base decreased up to 20 DAH and then increased up to 40 DAH. Cellulose content increased up to 20 DAH, but hemicellulose and lignin did not change significantly during the ripening stages. Starch, cellulose, hemicellulose, and lignin contents of culm base did not correlated with breaking strength and time of paclobutrazol application did not show consistent results. Paclobutrazol applied 13 DBH did not reduce yield of rice. but the earlier applications reduced yield due to a reduced number of spikelets per panicle.