• Korean Journal of Soil Science and Fertilizer
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• v.29 no.1
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• pp.3-7
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• 1996

Effects of the nitrogen application time and amounts on the nitroger. uptake and recovery of fertilizer nitrogen applied at panicle formation stage was investigated in connection with the growth and yield of rice drill-seeded in puddle-soil. silt loam of Jeonbuk series. Urea was applied as nitrogen source. Nitrogen uptake and recovery of fertilizer nitrogen by rice plant was highest in the treatment applied nitrogen at 20 days before heading. Culm length, internode length (4th and 5th) and lodging index were increased by earlier application time and higher level of nitrogen. but filled grain ratio and 1,000 grain weight showed the opposite trend Panicle number per square meter and grain number per panicle was significantly decreased in nitrogen application at 10 days before heading. Rice yield was the highest in 33kgN/ha(conventional amount at 20days before heading, and yield in 26kgN/ha(80% of conventional amount) at 20 days before heading and in 33kg/ha at 15days before heading were nearly the same as conventional treatment.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.11
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• pp.1-9
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• 1972

For a measure against late transplanting, this experiment was conducted to investigate a reasonable seeding rate in nursery bed and a proper nursery size. The treatments applied to this experiment are as follows a) seeding rates: 0.2ι, 0.4ι and 0.6ι per 3.3$m^2$ b) nursery sizes. for 10a-field area: 39.6$m^2$, 49.5$m^2$ and 59.4$m^2$ c) transplanting dates: June 5, June 25 and July 15. The seeding date was April 26 and planting density was determined by the number of sound seedlings based on the combination of seeding rate and nursery size. The results may be summarized as follows: 1. In seedlings both increased nursery period and decreased seeding rate showed a remarkable-increase in plant height, number of leaves, dry matter weight and the ratio of dry weight to plant height. But their number of tillers and live leaves did not show such tendency. 2. Delayed transplanting date shortened culm length and panicle length as well as number of days from transplating to heading and it also delayed heading date. On the other hand the transplanting of 80-day seedlings resulted in premature heading. 3. As a result late transplanting reduced number of spikelets per panicle, maturing rate and 1000-grain weight. In the last analysis it linearly reduced grain yield. The decreasing rate of yield by late transplanting was 15.6% in June 25 plot and 41. 3% in July 15 plot, compared with the yield in June 5 plot. Such a remarkable decrease in yield of the extremely late transplanted plot was mainly due to markedly decreasing number of spikelets per panicle and 1000-grain weight. 4. Both increased seeding rate and nursery size gave a rise in number of tillers per unit area as well as number of transplanting hills but gave a fall in culm length and panicle length. 5. Accordingly, though thick seeded - dense planted plot increased number of panicles per unit area, decrease in number of spikelets per panicle and 1000-grain weight made no differences in yield between thick seeded - dense planted plot and thin seeded - sparse planted one. However, the yield in the thick seeded - dense planted plot transplanted on July 15 was reduced owing to the remarkable decrease in maturing rate and 1000-grain weight. 6. We came to the conclusion that as a measure against the extremely late transplanting the suitable seeding rate was 0.4ι per 3.3$m^2$ and the proper nursery size was 59.4$m^2$ for 10a-field area.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.66 no.4
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• pp.297-306
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• 2021

To select rice (Oryza sativa L.) cultivars suitable for forage-rice double cropping system, the growth and grain quality of four early maturing rice cultivars (Joun, Jopyeong, Haedamssal, and Unkwang), and the chemical properties of soils were investigated under single- (fallow-rice) and forage-rice double-cropping systems in paddy fields in Miryang, southern Korea. The soil where two forage crops [Italian ryegrass (Lolium multiflorum Lam.) and oat (Avena sativa L.)] were cultivated during winter had a slightly lower pH; an increase in total nitrogen (T-N), K, Ca, and Na contents; and a slight decrease in organic matter and available P₂O₅ contents, compared with the soil fallowed during winter. This shows that the chemical properties of paddy soils can be improved by winter forage cropping. At the heading stage, the culm length, panicle length, panicle number, and leaf color of all cultivars, except for Haedamssal, were generally higher under double-cropping than under single-cropping. For Haedamssal, the culm length and leaf color did not differ between the cropping systems, but the panicle length was slightly shortened and its panicle number increased under double-cropping. After harvest, the yield of milled rice decreased for all cultivars except Haedamssal, but increased in Haedamssal under double-cropping. The head rice rate was slightly higher under double cropping, particularly in Jopyeong and Haedamssal, than under single-cropping. The protein content of milled rice under double cropping was higher and its amylose content was similar or slightly lower compared to those of rice under single cropping, resulting in decreased Toyo values for rice under double-cropping. The pasting temperature did not differ significantly between the cropping systems. However, Haedamssal had a low pasting temperature but a high Toyo value under double cropping, compared to the other three cultivars, suggesting that its palatability is relatively high. Furthermore, panicle number increased and milled rice yield did not decrease, even under double cropping. Therefore, Haedamssal seems to be the best cultivar for paddy-based double cropping with forage crops.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.37 no.1
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• pp.37-44
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• 1992

Germinability, electrophoretic variation of protein of shattered seeds during overwintering and characteristic of main agronomic traits of off-type rice plant occurring in paddy field harvested by combine were investigated. Germinability of shattered seed decreased as time goes in paddy field in both Japonica and Tongil type varieties. Electrophoretic protein bands become more and more light as time goes. Occurrence of off-type rice plant was higher in Japonica varieties than in Tongil type varieties. Off-type rice plant was shorter in plant height, leaf length, tiller number per hill, internode length, panicle length and spike let number per panicle. Germinability of seeds of off-type rice plant as not significantly different compared to the control variety. Yield of off-type plants of Japonica varieties was on average 5.1kg / 10a and that of Tongil type varieties was on average 0.9kg /10a. Mixing ratio to the control variety was about 0.7% in Japonica varieties and that of Tongil type varieties was about 0.1%.

• Korean Journal of Agricultural Science
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• v.29 no.2
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• pp.5-9
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• 2002

Culm length of Dohoku mutant 1(DM 1) and mutant 2(DM 2) were shorter than Dohuko parent and Heukjinjubyo check, while days to heading were delayed seven to 20 days Panicle length of these were similar to check and number of panicle per plant of DM 2 was highly appeared than check. Spikelets per plant of the selected lines were lower than check, and glume color of these were varied from brown to dark purple and awn length was also varied according to line used. Anthocyanin content of each mutant line as measured by 530nm were lower than that of check in that OD 2.23 and OD 2.26 for DM 1 and DM 2, respectively, and 2.59 for check.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.6
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• pp.539-543
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• 2006

Lodging is classified as root lodging caused by the loss of supporting force in the root, bending caused by the deformation of the stem and breaking where the stem breaks down as loads exceeding critical elasticity were applied. This research excluded breaking which is not in a state of equilibrium and tried to partition the level of lodging using an algebraic model in root lodging and stem lodging, or bending. When a vertical load was applied, the deformation of the stem of rice plant showed the form of a quadratic equation. The trace of the panicle neck in the process of lodging was an ellipse-shape. When loading was pure root lodging, the trace of the panicle neck became a circle of which culm length is the radius. When it was a pure stem lodging, the trace of the panicle neck is an ellipse of which major axis is culm length and minor axis is 0.64* culm length. When both stem lodging and root lodging occurred in a natural setting, the partitioning of lodging can be calculated by a formula using eccentricity of an ellipse, S=e*100/0.768(S is the ratio of stem lodging in the whole lodging, e is eccentricity of the ellipse). This method is expected to be useful in simple lodging partitioning. We could also calculate the partitioning of stem lodging and root lodging as units of angles as an accuracy method, by using a straight line calculated by differentiating a quadratic equation of stem deformation at the origin of the coordinates. These two methods for dividing root and stem lodging showed different values. However, each of them showed almost same values with different lodging degree in one plant.

• Korean Journal of Plant Resources
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• v.19 no.4
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• pp.497-508
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• 2006

This study was conducted to obtain the basic information on rice cold damage and relationship to be connected with cold tolerance. The 20 rice varieties were screened to cold tolerance under low water temperature condition. The water gradient were controlled to $17^{\circ}C$ at the inlet and $21^{\circ}C$ at outlet of screening field. In the relationship between cold water irrigation and growth of rice varieties, effect on medium maturing cultivars were higher than early maturing cultivars. In relationship of shorting of culm length and panicle exsertion, culm length and panicle exsertion showed positive correlation. Yield of cultivars and culm length and percent of fertile grain showed positive correlation. However, heading date presented negative correlation. In the early maturing cultivars, except 'Kumobyeo', all cultivars range of discoloration value (1-3) was resistant. In the medium maturing cultivars, 'Donghaebyeo' was resistant in both the seedling stage whereas 'Hwajinbyeo' was resistant only in tiller stage. Cold water irrigation reduced spikelet number per panicle and percent of filled grain. Unhulled rice yield was increased according to water temperature gradient from inlet to outlet. There was varietal differences in head rice recovery by cold water treatment.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.35 no.3
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• pp.218-223
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• 1990

This experiment was carried out to obtain basic information on the lodging characteristics and yield components of rice plants by new anti-lodging reagent 'KIM-112' (3%, Wp) application at 30 days before heading (DBH) to 5 DBH under two dosage levels (lg 2g, a. i. /10a) at the Yeongnam Crop Experiment Station in 1989. Culm length was shortened by 10-17% at 1g, a. i. /10a and by 16-23% at 2g of KIM -112 applications. The shortening effect of internode was different by dosages and application times: 2g treatment was greater effect than 19 and early application resulted in shortening of lower internode while this was upper internode at the late application. There were positive correlation between culm length and lodging index, the 1st and the 4th internode lengths had on important effect to lodging index. Thickness of culm wall, culm diameter and weight of basal part of culm were not affected by KIM-112 application. However anti-lodging characters improved by increasing the breaking weight and by decreasing the moment. Lodging index was related to breaking weight, moment and weight of panicle. Heading date by KIM-112 application was delayed one to four days and number of grains per panicle was decreased by shortened panicle length as compared with untreated control, but yield capacity was high a little because of improvement ripening ratio by no lodging.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.40 no.2
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• pp.203-211
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• 1995

This study was conducted to know how low temperature response of rice varieties is available for breeding lines adapted to cold weather. Some agronomic characters related to cold tolerance were evaluated for 188 varieties including three varietal types of Japonica, Tongil, and Indica. Cold tolerance of Japonica and Indica type varieties varied in leaf discoloration, heading delay, reduction of culm length, panicle number, spikelet number, panicle exsertion, spikelet fertility, and phenotypic acceptability at maturity, while Tongil type varieties were susceptible in most agronomic characters. In leaf discoloration, most Japonica type varieties were highly tolerant, while Indica type varieties showed various responses from tolerant to susceptibility. Not significant difference among three varietal types was observed on reduction of panicle number and spikelet number due to low temperature.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.38 no.6
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• pp.554-559
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• 1993

This experiment was carried out at Chuncheon substation, Crop Experiment Station to investigate the effect of cold water irrigation on the growth and grain yield of rice in 1990. Irrigation of cold water (17$^{\circ}C$) delayed 10 to 19 days of heading, and reduced about 17 to 31% of plant height in terms of culm and panicle length. Number of panicle per plant was decreased and / or increased by cold water irrigation. Cold water irrigation reduced spikelet number per panicle and percent of filled grain. Grain yield was increased but, straw weight was decreased according to water temperature gradient from inlet to outlet. There was varietal differences in head rice recovery by cold water treatment. In general the dark brown and / or black colored kernel increased at cold water inlet but decreased percent of green kernel. Alkali digestible value increased and amylose content decreased at cold water inlet.