• Korean Journal of Weed Science
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• v.7 no.1
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• pp.45-51
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• 1987

This experiment was conducted to find out the critical competitive period and competitive ability of rice against red rice. Plant height and number of tillers of rice decreased as red rice competed with rice during active tillering stage. The maximum tillering stage of rice competed with red rice became about 10days earlier than those non-competed. Significant yield reduction of rice was observed in the plots competed for 20 days after transplating or longer. Such a yield reduction can be mainly attributed to the decrease in number of panicles per hill and grain number per panicle. In a replacement diagram for rice and red rice, their competition is turned out being antagonized. The relative yield total was considered lower than 1. Grain number, culm and panicle length of rice was not affected significantly by inter-specific competition. Rice grain yield reduction was highly correlated with the number of panicles of red rice. Three hundred panicles/$m^2$ of the red rice were necessary to reduce rice grain yield by 50% of the check plot.

• Korean Journal of Plant Taxonomy
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• v.43 no.1
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• pp.56-62
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• 2013

Echinochloa oryzoides (Ard.) Fritsch (Na-do-non-pee), was found at paddy fields of Jeonranamdo on a large scale after a first discovery at Masan, Kyeongsangnamdo. This species was not easily distinguished from rice before flowering at the paddy field because of a similar morphology to rice. It is, however, distinguished from other species of the Korean Echinochloa by reliable morphological characters such as horizontal or drooping panicles at maturity, lower glumes with usually 1/4-2/5 as long as the spikelets, awned lower lemmas, and the number of chromosomes, 2n = 54. Echinochloa oryzicola (Vasinger) Vasinger was distinguished from E. oryzoides by erect panicles, lower glumes with at least 1/2 as long as the spikelets, and the number of chromosomes, 2n = 36.

• 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.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.35 no.4
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• pp.309-314
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• 1990

A pot experiment was carried out to find the effects of chemicals and its application time on the sterility and other agronomic characters of rice. Two rice cultivars, Samgangbyeo, a Tongil type, and Chuchungbyeo, a japonica type rice were treated with maleic hydrazide (6000ppm), ethephon (6000ppm) and GA3 (10ppm) at five different growth stages. The application times of chemicals were comprised of two different stages of stem elongation and booting and panicle emerging stage. Grain sterility and panicle length were measured for panicles per pot. Culm length was measured for pot basis. MH induced complete grain sterility in rice, but caused severe plant damage (phytotoxicity) ; restricted spike emergence and drying out of plant leaves, sheath and panicles. Ethephon induced 50-60% grain sterility in rice with the least in plant damage. GA3 was not effective in inducing grain sterility in rice, but it increased culm length. The earlier application of chemicals, the higher sterility was induced. Both MH and ethephon reduced culm length and grain yield. Also observed was the varietal response in the occurrence of to chemicals Samgangbyeo showed the higher response to chemicals than Chuchungbyeo.

• Current Research on Agriculture and Life Sciences
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• v.23
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• pp.1-8
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• 2005

The purpose of this study was carried out to determine the optimum sowing date and days after sowing (DAS) in automatic facility located at Uiseong of Gyeoungbuk province. The seedling height was rapidly increased with a delay of sowing time from April to May. The 10-day old seedlings with suitable plant height (> l0cm) for machine transplanting in the facility were obtained when the seeds sowed after May 20 at Uiseong in Gyeoungbuk province. The dry weight-height ratio of 10-day old seedlings was significantly decreased when the seeds sowed after June 20, and 15-days old seedlings did after May 10. No. of panicles/hill was reduced with increasing of days after seeding. But there were no significant difference among other yield components such as no. of grains/panicle, ratio of ripened grains, and 1,000 grain weight. The highest grain yield, 748kg/10a, was attained from the 10-day old seedlings transplanted at May 27 in comparision with those of 15-day and 20-day old seedlings. The grain yield of 10-day old seedlings transplanted at June 26 was also higher than that of 15-day old seedlings.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.35 no.6
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• pp.512-517
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• 1990

This experiment was conducted to evaluate the tillering behavior of low- and high-tillering rice plants, IR58. a high-tillering cultivar with small panicles showed not only higher tiller number but also earlier tillering, faster tillering rate and longer tillering duration than IR25588. a low-tillering cultivar with large panicles, Tillering ability of IR25588 was only 59% that of IR58, Percent effective tillers was higher in IR25588(85%) than in IR58 (67%), Tillering response to wider spacing was higher in a high-tillering cultivar than in a low-tillering cultivar, Grain yield response to closer spacing (close spacing adaptability) was higher in a low-tillering cultivar than in a high-tillering cultivar.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.301-301
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• 2017

Subspecific difference of the percentage of white immature kernels (WIK) between japonica and indica rice cultivars was analyzed in relation to ripening temperature and yield characters. Thirty-three Chinese and 10 Japanese rice cultivars, including 32 japonica and 11 indica, were cultivated with three different cropping seasons for three years. The results were as follows: (1) Indica had less number of panicles, larger number of spikelets per panicle with higher yield, and longer and narrower kernels than japonica. In japonica, Chinese cultivars had less number of panicles and larger number of spikelets per panicle than Japanese cultivars. In addition, WIK was significantly higher in Chinese cultivars than in Japanese cultivars, because of the higher percentage of milky white kernels, even at similar temperature conditions during ripening. On the other hand, WIK in indica was not significantly different between the production areas and between the cropping seasons. (2) Regardless of subspecies, WIK in a large number of Chinese cultivars increased with increasing temperature during ripening within 20 days after heading, while this relation was uncommon in Japanese cultivars, showing the low temperature response. However, some Chinese cultivars had the low WIK with the low temperature response. (3) WIK in japonicawas positively correlated with 1000-kernel weight, spikelet density, kernel width and thickness, but negatively correlated with panicle length and grain filling percentage, while in indica it was positively correlated with panicle number per area, grain filling percentage, brown rice yield and kernel width, but negatively correlated with kernel length. These results indicated that WIK in both subspecies had a close relation to kernel size, and that WIK was high in japonica cultivars with wide and thick kernels and in indica cultivars with short and wide kernels.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.17
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• pp.143-148
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• 1974

Field and pot experiments were conducted for the split application of potash in paddy (Oryza sativa L. cultivar Jinheung.) Production and the experimental results were analysed with regard to the yield of paddy and its yield components. The absence of potash at the reproductive stages such as primodial and heading period but supplied most of the potash at the early growth stages, resulted in an increase of panicles but in a decrease of grain numbers per panicle and yield of paddy. On the other hand, however, the reduced amount of potash application at the earlystage of growth showed a decreased number of panicles and yield of paddy, particulary where lime and fresh rice straw were applied.

• Journal of Korean Society on Water Environment
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• v.21 no.2
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• pp.169-175
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• 2005

This study was carried out to investigate the effects of irrigation water pollution on the yield and grain quality of rice. It acquires fundamental data to set up water quality standards for irrigation and produce agricultural safety products. The correlations of BOD, T-N, T-P, pH, ECw of the irrigation water with yield, grain appearance quality, and the protein content were evaluated. The field and pot experiments were conducted by using Japonica of Oryza sativa L. during 2 years. BOD concentration in irrigation water effects strongly on grain appearance quality and yield of rice. T-N in irrigation water has strong effect on the yield, appearance, and quality of rice. T-P concentration in irrigation water have not any correlation with yield and quality of rice. pH showed strongly negative correlation with maturity ratio(MTR), 1000 grain weight(TGW), and yield of rice(YLD) as r=-0.803~-0.828(p<0.001) and have no effect on the appearance quality of rice. $EC_w$ indicating salt content showed strongly negative correlation with MTR, TGW, number of grains per panicles(NGP), and number of panicles per unit area(NPM) as r=-0.759~-0.798, and with YLD as -0.753.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.33 no.2
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• pp.195-200
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• 1988

This experiment was carried out to evaluate the flooding injury and yield compensating ability by uppernode tillers formed during the recovery periods. Rice plants grown in experimental field transplanted on 1st, June were completely flooded for 3 days by the artificial flooding device in each different growth stage such as middle tillering stage (20 days after transplanting), young panicle formation stage, meiotic stage and heading stage. And the farmer's rice fields which had various transplanting dates were completely flooded for 3 days by typhoon 'Thelma' from 16th to 18th, July, 1987. Percent of dead leaves and yield reduction of rice in experimental field flooded at the different growth stages were resulted that the earlier growth stages were the lower damage because of the low temperature in the earlier growth stage, but it showed opposite tendency in farmer's rice field flooded in high temperature season by typhoon 'Thelma'. Rice yield compensating ability attained to 66% of check plot yield was greatly depend on uppernode panicles induced after damage of original young panicles. Uppernode panicle produced 236 kg per 10a in polished rice by securing 690$^{\circ}C$ of accumulated mean temperature and 210 hours of sunshine during the ripening periods when headed up to 15th of September.