• KOREAN JOURNAL OF CROP SCIENCE
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• v.37 no.6
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• pp.514-520
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• 1992

Performance of direct seeded paddy rice in ridged dry soil was evaluated at different seeding methods (broadcasting, drilling, and seeding in group) and seeding rates (4, 6, and 8kg /10a). The number of maximum tillers at broadcasting and drilling of seeds was higher than that at seeding in group. At broadcasing and drilling the number of maximum tillers at seeding rate of 6kg /10a was greater than that at 4 or 8kg /10a, but at seeding in group the number of maximum tillers increased with seeding rates. Among the seeding methods there were no differences in the number of seedlings per unit area, culm and panicle lengths, and productive tiller ratio, but heading date at seeding in group was delayed by a day compared with broadcasting or drilling. At heading stage leaf area index(LAI) and dry matter production at broadcasting of seeds were higher compared with drilling and seeding in group, but light transmission ratio at drilling and seeding in group was higher than that at broadcasting of seeds. Although the number of seedlings increased with seeding rates, LAI and dry matter production at heading stage, culm and panicle lengths, and productive tiller ratio were not different among the seeding rates. There were no differences in the number of panicles and spikelets per unit area, 1,000 grain weight, yield, and harvest index among the seeding methods. The number of spikelets per panicle at seeding in group was higher, but percent ripened grains was lower compared with broadcasting and drilling. There were no significant differences in the number of panicles and spikelets per panicle and unit area, percent ripened grains, and harvest index among the seeding rates, but yield at seeding rate of 6kg /10a was higher than at 4 or 8kg /10a. There were no significant differences in tiller length, bending moment, and fresh weight of tiller among the seeding methods. Breaking strength was lower in the order of seeding in group, drilling, and broadcasting of seeds. However, lodging index was similar among the seeding rates and lodging was not occurred in the field. There was a significant interaction in the cellulose, hemicellulose, and lignin contents of culm base between seeding methods and seeding rates.

• Magazine of the Korean Society of Agricultural Engineers
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• v.28 no.2
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• pp.31-41
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• 1986

Knowledge of the degree of yield reduction due to water stress at different crop growth stages in rice production is important for rational scheduling of irrigation during periods of insufficient water supply. Previous studies to determine the degree of yield reduction duo to water stress suffered from interruptions by rain during experiment. Also the findings did rot relate the degree of water stress to the soil water potential and water deficit status of rice plants. In this study, two years experiments were conducted using the high yielding rice varieties, an Indica x Japonica (Nampoong) and a Japonica variety(Choochung). These were grown in 1/200$^{\circ}$ plastic pots placed under a rainfall autosensing, sliding clear plastic roof facility to control rainfall interruptions. The results obtained were as follows. 1.The two varieties differed in the growth stage most sensitive to water stress as well as the degree of yield reductions. When rice plants were stressed to the leaf rolling score 4 and soil water potential of about - 20 bar at major crop growth stages which included heading, booting, non-effective tillering, panicle initiation and early tillering stages, the yield reductions in the Indica x Japonica variety were 58%, 34%, 27%, 22%, and 21%, respectively, whereas in the Japonica vairety they were 23%, 36%, 1%, 13% and 22%, respectively. This result show that the recommended drainage during non-effective tillering is valid only for the Japonica variety. Sufficient irrigation at booting, heading and early tillering stages are necessary for both varieties. 2.The two varieties showed visible wilting symptoms when the soil water potential dropped to about - 3.0 bar. The Japonica variety showed more leaf rolling than the Indica X Japonica. However, it had a higher retention of leaf water content and greater stomatal diffusive resistance. When the soil water potential dropped, the Japonica variety showed leaf rolling score (LRS) 1 at 0 soil-5. 0 bar and LRS 2 at 0 soil -6.0 bar while the Indica X Japonica showed LRS 1 at 0 soil - 5.5 bar and LRS 2at 0 Soil - 9.0 bar. The stomatal diffusive resistance was maximum at the second top leaf blade in both varieties at intermediate water stress of 0 soil - 4.5 bar. 3.The number of days that was required for the soil water potential to drop to-3. 0 bar and to - 20.0 bar after drainage of irrigation water from the 20cm deep silty clay loam soil in the pots were 6 and 13 days, respectively for booting stage, and 7 and 11 days, respectively for heading stage, 9 and 12 days, respectively for panicle initiation stage, and 12 and 19 days, respectively for early tillering stage. 4.Water stress during the early tillering stage recorded the longest delay in beading time, the largest reduction in panicle numbers and a substantial yield decrease of 20%. This calls for better water management to ensure the availability of water at this stage, particularly during drought periods. In addition, a reexamination of the conventional inter-drainage practice during the non-effective tillering stage is necessary for the high yielding Indica X Japonica varieties.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.327-327
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• 2017

The effect of different seedling ages and transplanting times on the growth and yield of Indica ${\times}$ Japonica rice for noodle processing was evaluated to develop a high yielding cultivation technology for increasing the competition against the imported foreign rice. Four seedling ages (10-, 20-, 30- and 33-day old) of two Indica ${\times}$ Japonica rice cultivars (cvs. Saemimyeon and Palbangmi) and three transplanting dates (May 20, May 30 and June 9) were used in the study. Our results showed that the growth and rice yield of the two cultivars were significantly affected by the different seedling ages and transplanting times. Dry matter production at the panicle heading of the two rice cultivars were generally higher in the 30-day old seedling than the other seedling age treatments and then gradually decreased as the transplanting time was delayed from May 20 to June 9. Similar high panicle number per square meter were recorded at the 30-day old seedling between May 20-May 30 transplanting times. In contrast, other yield parameters that includes spikelet number per panicle, 1,000-brown rice weight, and ripened grain ratio (except for the June 9 transplanting time of Palbangmi) were not significantly affected. The milled rice yield of Saemimyeon was higher than that of the Palbangmi regardless of seedling ages and it was also the highest at the 30-day old seedling with four seedling ages. The milled rice yield of Saemimyeon was only slightly decreased as the transplanting time was delayed from the May 20 to June 9 but Palbangmi had a significantly lower milled rice yield at June 9 transplanting due to the low ripened grain ratio. The result indicates that the most suitable seedling age for the cultivars tested was at 30-day old seedling for noodle processing rice and recommended transplanting times were between May 20 and May 30 for the high rice yield in the Yeongnam plain area.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.60 no.4
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• pp.431-435
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• 2015

Rice (Oryza sativa L.) ratooning is the production of a second rice crop from the stubble left behind after the main crop harvest. The objectives of this study were to evaluate the effects of main-crop stubble height, irrigation and fertilization on ratoon grain yield. Main crop 'Jinbuol' rice cultivar was harvested to leave with 10, 20, 30, or 40 cm stubble height. When the main crop stubble was harvested with 10 cm height, ratoon rice grain yield was increased by 2,810 kg/ha. Irrigation on stubbles after main crop harvest did not affect the ratoon crop yield and rice quality. The results showed a large variation in the ratoon performance by fertilizer application methods. Top-dressed nitrogen fertilizer on the stubble after harvest caused increase in panicle production and higher maturity rate. However, there was no significant difference in protein content, amylose content of milled rice and cooked rice characters between plots managed with and without nitrogen fertilizer.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.39 no.3
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• pp.262-269
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• 1994

This study was conducted to clarify high yielding factors of F$_1$ hybrids in terms of the growth characteristics, canopy structure, nitrogen content and nitrogen profile in the canopy. Varieties used in this study were four hybrid rices showing different heterosis in grain yield and their parents. Varieties of Japonica were Reimei (maintainer), TP 681 and TP 1278(restorers), and F$_1$ (Reimei ms ${\times}$ TP 681, Reimei ms ${\times}$ TP 1278) hybrid rices. Those of Indica type were 1378 (maintainer), Milyang 46 and Suweon 287(restorers), and F$_1$ (1378 ms ${\times}$ Milyang 46, 1378 ms ${\times}$ Suweon 287) hybrid rices. High heterosis in F$_1$ hybrid rices were shown in panicles per hill and spikelets per panicle, being greatest in spikelets per panicle. Spikelets per square meter expressed even greater heterosis than those two yield components because of multiplicative effect of them. Heterosisof ripened concentration of leaf nitrogen and steeper gradient of leaf nitrogen in canopy strata but also better productive structure in favor of light interception seemed to have led to higher canopy photosynthesis of F$_1$ hybrids and subsequent higher partition of assimilates for leaf area expantion especially during vegetative growth stage. Higher dry matter production, resulting from these factors, during vegetative stage would have contributed to the production of greater number of spikelets per square meter, and consequently to higher grain yield in F$_1$ hybrids.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.22 no.1
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• pp.110-134
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• 1977

Effects of phosphorus, potassium and calcium applications on root activity and agronomic characters of paddy rice were studied in submerged paddy soil on which starch was applied to accelerate soil reduction and production of toxic substance during 1971～1973. Root activity at heading date was decreased in reduction accelerated soil by starch application. Effect of calcium application on root activity was differed along soil conditions, phosphorus or potassium levels. Single effects of phosphorus or potassium application were not significant on every observed characters. Calcium application when phosphorus or potassium was not used as basal but used as top dressing increased yield and yield components, especially filled grain ratio. Effect of calcium application along soil conditions was differed on agronomic characters, but calcium application with phosphorus or potassium was more effective to increase yield components and grain yield. Sufficient application of phosphorus, potassium and calcium could improve the nutritional situation of rice plant for panicle development and grain maturity in reduction accelerated paddy soil in which poor growing of rice plant after panicle formation is anticipated by the production of toxic substance from soil.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.61 no.2
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• pp.87-91
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• 2016

Recently, rice growth and production have been influenced by climatic change worldwide. In particular, under low solar radiation and cloudy weather, rice plants show abnormal physiological responses. In this experiment, plants of the rice cultivar Samgwangbyeo grown 40% and 70% shading and natural conditions at the primordium initiation stage (PI) for 30 days and the booting stage for 10 days up to heading were compared. After shading treatments, culm lengths were significnatly longer than that in natural condition plots, and panicle lengths were shorter in the 40% and 70% shading treatment plots compared to control plots. After heading, the production of dry matter treated at the PI stage was significantly lower than that at the booting stage. SPAD values of the leaf color and N concentration of leaves treated with shading were greater than those under natural conditions. In the shading treatment, the lodging index at 20 days after heading was significantly higher than that in natural condition. For yield components, number of panicles, spikelet number per panicle, and ripened grain ratio significantly decreased with shading treatment; thus, rice yield decreased significantly. For rice quality, the protein content of the head rice treated with shading was significantly higher than that in the control plot, but the amylose content of rice treated with shading was signifiantly lower than that in rice in control plots.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.317-317
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• 2017

We performed this experiment to select high quality rice adapted to wheat-rice double cropping system. We sowed barley and wheat seed in November 2, 2015. After harvesting barley and wheat, we transplanted high quality rice cultivars: 'Unkwang', 'Hopun', 'Haepum', 'Hyunoum' in June 17 and 24. We used 'sindongjin' rice as a control. As a result, 'Hyunpum' had a highest head rice yield regardless of transplanting date. Head rice yield of 'Hyunpum' was 488.1kg/10a when transplanted in June 17, and 453.6kg/10a when transplanted in June 24. The reason for this highest head rice yield was not percentage of head rice but milled rice yield. Milled rice yield of 'Hyunpum' was 526.5kg/10a when transplanted in June 17, and 490.0kg/10a when transplanted in June 24. Percentage of head rice had little differences between rice cultivars. Among yield components, only number of panicle per $m^2$ had an effect on the differences of yield between rice cultivars. The other yield components didn't have an effect on the differences of yield between rice cultivars. Compared to June 17, only 'Unkwang' had higher head rice percentage and head rice yield in June 24. Head rice percentage of 'Unkwang' changed from 67.3% to 85.0% and head rice yield changed from 324kg/10a to 393.8kg/10a when transplanting date delayed from June 17 to June 24. When transplanting date was delayed, heading date of 'Unkwang' was more delayed than other rice cultivars. By delay of heading date, mean temperature for 40days changed from $25.0^{\circ}C$ to $22.9^{\circ}C$ which improved temperature condition during grain filling stage. This improved head rice percentage and head rice yield of 'Unkwang' transplanted in June 24. If transplanting date is more delayed than June 24, 'Unkwang' could have higher head rice percentage and head rice yield. Therefore, if you transplant rice before June 24 in rice-wheat double cropping system, 'Hyunpum' is recommended as adequate rice cultivar. But if you transplant rice after June 24, further research is needed to find out adequate rice cultivar.

• Journal of The Korean Society of Grassland and Forage Science
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• v.23 no.2
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• pp.107-114
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• 2003

Growth characteristics and seed productivities of orchardgrass "Hwabsung 2 Ho" cultivated for seed production were examined in the NLRI from 2000 to 2002. The experimental design was a split-plot arrangement with three replications. The main-plots were three drill widths of 15, 30 and 45cm, and subplots were four nitrogen application levels of 45, 90, 135 and 180kg/ha in early spring. Lodging was less in 45cm of drill width than in 15 and 30cm and was not severe by 90kg per ha of nitrogen including 45cm of drill width. Number of panicles per $1\m^2$ was tended to be more in 15cm of drill width than in 30 or 45cm. Among 45cm of drill widths. 45kg per ha of nitrogen had most numerous panicles. Panicle length, number of 1st branch, weight of 1,000 grain, and germination of 30 or 45cm of drill width showed better characters than that of 15cm. Seed yield was not statistical different among the treatments but was some more in 30cm of drill width, and was tended not to be different among nitrogen levels. Therefore, considering lodging tolerances, seed yield components, and mechanizations, treatment with 45cm of drill width including 45kg per ha of nitrogen in early spring was better than other treatments for orchardgrass seed production.

• Weed & Turfgrass Science
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• v.6 no.2
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• pp.124-129
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• 2017

The Experiments were conducted by moderate season culture of each of early, medium and late maturing varieties which were considered to be of strong salt tolerance in low and high salty reclaimed areas (0.2% at the May). This study was carried out to investigate the proper nitrogen fertilizer level and seeding rates at reclaimed saline land in Korea. The proper seeding rates were $40kg\;ha^{-1}$ in 0.2% saline land. The dry matter production of barnyard millet was possibly estimated by exponential functions of $Y=0.0098X^2+0.7030X+2.6267$. Effects of nitrogen rate on agronomic characteristics, forage yield, and chemical composition of barnyard millet to reclaimed tidal land are summarized as follows: The proper nitrogen fertilizer level was $200kg\;ha^{-1}$ in 0.2% saline land. N was absorbed actively before the emergence of the barnyard millet but showed relative decrease thereafter. The early growth of the barnyard millet was inhibited, resulting in the favorable late growth, increased panicle weight and ratio of matured grain. These results suggest that barnyard millet is the most forage crops for cultivation on reclaimed tideland in view of the good emergence and forage production.