• Journal of Korean Society for Atmospheric Environment
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• v.2 no.1
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• pp.11-21
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• 1986

The study was performed to investigate the effects of gaseous imission of sulfur dioxide and hydrogen fluoride on the growth of rice plant under stressed field conditions. The plants were cultivated in normal paddy fields where are 88 industrial plants operating with 285 smoke stacks emitting pollutants. There has been a number of reported studies (1, 3, 11, 19, 20) which deal with rice plant damages by air pollution under a simulated exposure experimental condition. Furthermore, these experiments were conducted to examine effects of a single pollutant on the plant. Furthermore, these experiments were conducted to examine effects of a single pollutant on the plant. In korea, however, there is no study reported in literature with respect to the in-situ dose-response relationship between rice pant reduction in yields and air pollution. This study is specifically dealt with multiple effects of sulfur dioxde and hydrogen fluoride on various plant growth indicators such as leaf damage, culm height, weight of grain, panicles per hill, spikelets per panicle and percent fertility.It appears that there is a good correlation between ambient concentrations of sulfur oxides and sulfur contents found in leaves with an average correlation coefficient of 0.868 within a 1% significance level. It is interesting to note that a better multiple correlation was found between percent leaf damage and sulfur and fluoride contentd found in leaf with a significance of 1% level. The yearly correlation coefficient ranges from 0.963 to 0.987 with an average being 0.971. It is, therefore, believed that a percent leaf damage may serve as a single indicator of pollutional damages to rice plant cultivating in fields. Regarding other factors to the diminution of rice plant growth in polluted atmosphere, it appears that a significant correlation to culm length and dry weight of grain with a 1% significance level whereas T/R ratio has a good correlation with lead damage within 5% significance level. An evaluation of data observed has demonstrated that both panicles per hill and percent fertility are significantly affected by air pollutants. As expected, hydrogen fluoride has more effects than sulfur oxide. It is, however, interesting to note that spikelets per panicles has slightly been affected while no indication of effects on 1000-grain-weight has been observed. This may lead to a conclusion that a reduction in yield of rice under polluted field conditions may have more been caused by the diminution of panicles per hill and percent fertility rather than by the diminution of spikelets per panicle and grain weight.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.36 no.1
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• pp.17-21
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• 1991

The study was performed to investigate the effects of gaseous emission of sulfur dioxide and hydrogen fluoride on the growth of rice plant under stressed field conditions. This study is specifically dealt with multiple effects of sulfur dioxide and hydrogen fluoride on various plant growth indicators such as leaf damage, weight of grain, panicles per hill, spikelets per panicle and percent fertility. It appears that there is a good correlation between ambient concentrations of sulfur oxides and sulfur contents found in leaves with an average correlation coefficient of 0.868 within a 1% significance level. A better multiple correlation was found between percent leaf damage and sulfur and fluorine contents found in leaf with a significance of 1% level. The correlation coefficient ranges from 0.807 to 0.978 with an average being 0.922. An evaluation of data observed has demonstrated that both panicles per hill and percent fertility are significantly affected by air pollutants. As expected, hydrogen fluorides have more effects than sulfur oxides. It is, however, interesting to note that spikelets per panicle has slightly been affected while no indication of effects on l000-grain weight has been observed. This may lead to a conclusion that a reduction in yield of rice under polluted field conditions may have more been caused by the diminution panicles per hill and percent fertility rather than by the diminution of spikelets per panicle and grain weight.

• 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 Environmental Agriculture
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• v.6 no.2
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• pp.53-65
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• 1987

The study was performed to investigate the effect of gaseous emissions of sulfur dioxide and hydrogen fluoride on the growth of rice plants under stressed field conditions consisting of 88 industrial plants operating with 285 smoke stacks emitting pollutants. As for the relationship between yields and yield components it is believed that the panicles per hill is the single most important component affecting the rate of yield of the rice plant. Based on the standard partial regression coefficient analysis, panicles per hill has the largest contribution to yield and the average contribution of 54%. Other components such as spikelets per panicle, percent fertility and 1000 grain weight are also contributing factors to yield, although far less so. Fluorine content in the leaf appear to have more negative effect on panicles per hill, percent fertility and subsequent overall yield than does sulfur content in the leaf. It is constantly observed and interesting to note that fluorine and sulfur content in the leaf appears to have no effect on spikelets per panicle and 1000 grain weight. Reduction in yield seems to be affected mainly by panicles per hill which are, in turn, affected more by fluorine content in the leaf as demonstrated by the standard partial coefficient analysis. Regarding the prediction sum of the square of the regression equation, the lowest value was found when nine variables were used for the analysis. The variables taken into consideration were the monthly sulfur and fluorine content in the leaf as well as the monthly percent of leaf damage during the months of June, July and August. A significant correlation is found between the actual and predicted yields by the regression equations selected as a result of a prediction sum of the square analysis.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.35 no.4
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• pp.370-374
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• 1990

A field experiment was conducted to investigate the influence of water weevil damage on growth and grain guality in rice. Plant height was shortened, number of tillers per hill decreased and maximum tillering stage delayed in damaged field by rice water weevil. Heading date was delayed by 1-2days, culm lenght shortened, panicle lengthened, number of panicles decreaced, number of panicles per spikelet increased, ripened grain ratio decreased in damaged field by rice water weevil. Yield per 10a was decreased 4-22% in damaged field compared with that in undamaged field by rice water weevil, yield loss in late transplanting (June 23) was larger than that in early transplanting (May 20). Imperfect kerml rice, especially green kernel rice, was increased in damaged field by rice water weevil.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.266-266
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• 2017

In recent years, adoption of the System of Rice Intensification (SRI) is spreading in most Asian countries, and more recently in Cambodia is one of the Asian countries with high adoptions of SRI. We conducted on-farm experiment to investigate the effects of SRI on rice growth and yield in the farmers' fields in rainfed region of southern Cambodia. The study was undertaken in rainfed lowland fields of Popel commune ($11^{\circ}$ 04' 67" N, $104^{\circ}$ 40' 79" E) of Tram Kak District in Takeo Province during the wet seasons in 2012, 2013, and 2015. A total of 32 on-farm experiments were conducted during the wet seasons for three years of 2012 (11 fields), 2013 (8 fields), and 2015 (13 fields). Across the three years of study, SRI produced significantly greater plant biomass and grain yield than Non-SRI. The yield increase was mostly ascribed for the increased number of grains per land area, which was due to the increased number of spikelets per panicle rather than the number of panicles per land area. With no significant difference between SRI and Non-SRI with respect to seedling age, the greater number of grains per panicle was accounted for by the reduced planting density and increased amount of manure application in SRI than Non-SRI fields. It was found that the greater manure application has increased soil nitrogen content in SRI and Non-SRI fields. While SRI did not increase the number of panicles per land area, it did increase the number of panicles per hill.

• Mycobiology
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• v.39 no.2
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• pp.113-117
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• 2011

A laboratory experiment was conducted to study the induction of constricting rings and test predation of Dactylaria brochopaga isolates against second stage juveniles (J2s) of Meloidogyne graminicola. Among the five fungal isolates, isolate D showed the greatest number of predatory rings and, consequently, trapped the maximum number of M. graminicola J2s in dual cultures. Another pot experiment was conducted to study the effect of D. brochopaga (isolate D) on the management of wheat root-knot disease. Applying a mass culture (10 g/pot) and a spore suspension of the fungus with and without cow dung manure to soil infested with 2,000 M. graminicola juveniles significantly improved plant height, root length, weights of shoots, roots, panicles and grains per hill compared to those in the control. Moreover, the fungus significantly reduced the number of root-knots, the number of egg masses, juveniles, and females per hill compared to those in the control. Bio-efficacy of the fungus was heightened when the mass culture and a spore suspensions were used in combination with cow dung manure to improve the plant growth parameters and reduce the number of root-knot and reproductive factors. Further investigations should be conducted to identify the impact of this fungus in the field.

• The Korean Journal of Mycology
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• v.12 no.4
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• pp.171-174
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• 1984

To investigate the relationship between symptom development of Bakanae disease and yield component (the length of panicle, weight of panicle, number of healthy grain per panicle and number of panicle per hill), rice seedlings infected with F. moniliforme were transplanted. The number of panicles per hill and healthy grain per panicle were greatly decreased by the development of Bakanae symptom. Yield components was not correlated with the time of the Bakanae symptom development. Rice plants with Bakanae symptom had lower yield as 210g per 10 hills than healthy plants as 469g per 10 hills.

• Korean Journal of Agricultural and Forest Meteorology
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• v.2 no.2
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• pp.41-46
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• 2000

This experiment was carried out to find out the responses of the growth characteristics to various air temperature in a high yielding indica/japonica rice cultivar, 'Dasanbyeo'. Five different transplanting dates with 30 day-old seedlings were tried to induce various environmental conditions, starting from 10th May to 19th June in the interval of 10 days at National Crop Experiment Station, in 1998. Planting densities with different plants per hill but same hill spacing were tested. The daily mean air temperature during 30 days after transplanting was 19.0, 20,8, 21.9, 24.4 and 25.2$^{\circ}C$ when transplanted on the 10th May, the 20th May, the 30th May, the 9th June and 19th June, respectively. The number of tillers per hill at 30 days after transplanting was affected by the daily mean air temperature during 30 days after transplanting. The higher the daily mean air temperature, the more tillers per hill at 30 days after transplanting were. The growth duration from transplanting to heading was greatly changed according to the transplanting dates. It was shortened as the transplanting date was delayed until transplanted on the 9th June, but it was prolonged when transplanted on the 19th June compared to that of the 9th June. The number of panicles per hill increased with the increase of the transplanted plants per hill up to 7 plants per hill. The number of panicle per unit area was closely related to the number of tillers per unit area at maximum tillering stage. It was found that the average effective temperature during first 10 tiller formation related to the days to the tenth tiller formation with the relationship of y = 1.071x$^2$ - 37.307x + 342.38($R^2$ = 0.9823).

• Korean Journal of Organic Agriculture
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• v.15 no.2
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• pp.207-218
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• 2007

Coming with the well-being era, consumer's demand for safe agricultural products is increasing. So, it is urgent to develop an environment-friendly rice production system. Accordingly, this study was conducted to develop an environment-friendly rice production system by using Amo known as EM(effective microorganisms) and also known as being effective in environment-friendly rice production with several other environment-friendly agricultural materials. The highest number of tillers per hill was obtained from level 2 of EM treatment (48.8 tillers per hill), while the lowest was obtained from the control plot (41.0 tillers per hill). Leaf area per hill at heading stage was the highest in level 3 of EM treatment $(3228.5cm^2)$, while control was the lowest leaf area $(2264.7cm^2)$, which is 70.2% compared to the level 3 of EM treatment. The highest effective tillers was obtained from the control (63.7%), while the lowest effective tillers was obtained from the level 3 of EM treatment (55.4%), which were treated with higher amounts of environment-friendly agricultural materials. Level 3 of EM treatment showed the highest number of panicles per hill (20.9), while the control showed the lowest number of panicles per hill (19.3). In the spikelets per panicle, level 2 of EM treatment showed the highest number of spikelets (85.2), while the control showed the lowest number of spikelets (81.9) and there was a statistically significant difference among the three levels and control. The highest grain filling ratio was obtained from the control (85.0%), while level 3 of EM treatment was the lowest grain filling ratio and there were no great difference between treatment levels. Regarding the 1000 grain weight, the control showed the highest 1000 grain weight (21.7g), which is heavier by about 1g compared to treatment levels. Level 2 of EM treatment showed the highest rough rice yield per 10a, while level 3 of EM treatment was the lowest and they also showed a statistically significant difference among treatment levels.