• KOREAN JOURNAL OF CROP SCIENCE
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• v.24 no.2
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• pp.57-63
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• 1979

This study has been carried out to find out the optimum plant density and number of seedling per hill in the late season culture of rice at Chung Buk. P.O.R.D. Up to the level of 33 hills per m2 and 6 number of seedling per hill, rice yield was increased as the number of seedling per hill and plant density per unit areas increased. However it is recommendable to have a plant density of 28~33 hills per m$^2$ with 4~6 number of seedling per hill for the late season culture.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.48 no.2
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• pp.120-126
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• 2003

Four different rice varieties, Sindongjinbyeo, Dongjin #1, Saegyehwabyeo, and Iksan 467, were transplanted under three different nitrogen levels and two different seedling numbers per hill to obtain basic information on panicle traits under different cultural conditions and to propose the ideal panicle structure in Japonica rice. Sindongjinbyeo and Iksan 467 were characterized by more primary rachis branches (PRBs) per panicle and more grains on PRB than other cultivars. The two varieties also had fewer secondary rachis branches (SRBs) per PRB and fewer grains on SRB per PRB. These characteristics, consequently, resulted in higher ripened grain rate, contrary to that of Dongjin #1 and Saegyehwabyeo. In the correlation coefficient analysis, PRB number per panicle and grain number on PRB per panicle were positively correlated with ripened grain rate, while SRB number per panicle, number of grains on SRB per panicle, SRB number per PRB, number of grains on SRB per PRB and grain number per panicle were negatively correlated with ripened grain rate. Therefore, the number of grains on PRB per panicle, SRB number per PRB and the number of grains on SRB per PRB were the appropriate criteria for determining and achieving higher ripened grain rate in rice. High ripened grain rate over 90% was obtainable with over 12.5 PRBs per panicle and 63 grains on PRB per panicle, and with under 1.7 SRBs per PRB, 5 grains on SRB per PRB, 130 grains per panicle, and 14 panicles per hill. The study recommended that for over 90% high ripened grain rate, the critical limiting factors should be under 2 SRBs per PRB, 6 grains per PRB, and 130 grains per panicle, irrespective of the PRB number per panicle and the number of grains on PRB.

• Proceedings of the Korean Society of Crop Science Conference
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• 1989.02a
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• pp.54-55
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• 1989

• Proceedings of the Korean Society of Crop Science Conference
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• 1989.05a
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• pp.32-33
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• 1989

• 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 CROP SCIENCE
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• v.30 no.3
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• pp.252-258
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• 1985

An experiment was conducted at the Yeongnam Crop Experiment Station to obtain basic informations about cultural techniques for high yielding by manipulating plant spacing using two rice cultivars, Samgangbyeo (Indica/Japonica type) and Nakdongbyeo (Japonica type), and four plant spacings, 10${\times}$10cm, 20${\times}$20cm 30${\times}$30cm and 40${\times}$40cm, with 4 kinds of seedling number per hill, 1,3,5 and 7, respectively. High photosynthetic efficiency (Eu) exhibited at the Samgangbyeo compared to Nakdongbyeo regardless of plant spacings and seedling numbers. For Samgangbyeo, Eu value was the highest at the 20${\times}$20cm plant spacing and five seedlings and seven seedlings per hill showed high Eu values at 10${\times}$10cm plant spacing and 20${\times}$20cm plant spacing, respectively, while other plant spacings were not significantly differed among seedling numbers. For Nakdongbyeo, however, one seedling plot obtained high Eu value at the 10${\times}$10cm plant spacing while this Eu value increased as the seedling number per hill increased in other plant spacings. There was a high positive correlation between rice grain yield and total competition index for both cultivars while kind of relationships differed in these two cultivars; linear relationship for Samgangbyeo and exponential relationship for Nakdongbyeo, respectively. Competition index between rice hill was more significant than within rice hill for Samgangbyeo while both competition indexs were important for Nakdongbyeo to increase rice yield.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.34 no.2
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• pp.127-133
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• 1989

An experiment was conducted at the Yeongnam Crop Experiment Station to obtain basic informations about cultural techniques for high yield by manipulating plant spacing in association with seedling number. Cultivars showing relatively low competition index within or between rice hill were Palgongbyeo, Milyang 83. Milyang 90 and Sangpungbyeo, while those with high competition index were Pungsanbyeo, Samgangbyeo, Weongpungbyeo, Taebaegbyeo and Dongjinbyeo. Variations of agronomic characters such as culm length, spikelets per panicle, grain yield per panicle among each culm within hill were not interrelated among the characters. This phenomenon was also same within and between cultivar groups. However, cultivars having high competitive ability showed relatively low variation in agronomic characters. There was a trend that most of rice cultivars had a high positive correlation between total competition index and rice grain yield. Competition index between rice hill was more significant than that of within rice hill for Tongil type cultivars except Milyang 83 which belonged to low tillering capacity while both types of competition index within and between hill were important for Japonica type cultivars and Milyang 83 of Tongil type cultivar to increase rice yield.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.34 no.1
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• pp.60-73
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• 1989

Two field experiments were carried out to assess the applicability of a central composite design (CCD) in determining optimum culture condition of an early rice cultivar, Unbongbyeo in southern Korea. A central composite design with two replicates was applied to five levels of five factors such as the number of hills per 3.3m2, the number of seedlings per hill, the levels of nitrogen, the transplanting date and the seedling age (Experiment 1). The levels of planting density were ranged from 30 hills to 150 hills per 3.3m2 ; the number of seedlings per hill from 1 seedling to 9 seedlings per hill; the levels of nitrogen application from 1 kg/l0a to 21 kg/l0a; the transplanting date from June 15 to July 5; the seedling age from 25 days to 45 days. A fractional factorial design was applied to three levels of five factors tested in CCD (Experiment 2). Yield per hill and per unit area were examined and the results obtained from both experiments were compared. The benefits from the central composite design were discussed. Maximum yield of brown rice per unit area was obtained at the combination of the central levels of one of five factors when the other four factors were fixed at central point. Furthermore, brown rice yield per unit area affected by interaction of two factors was maximized at the central point when the remain three factors being fixed at the central level. The responses of five factors to brown rice yield per hill and unit area were found to be a saddle point in both designs. Actual values of the stationary points were 107 hills per 3.3 m2, 4 seedlings per hill, 10 kg nitrogen per l0a, transplanting date of rice on June 26 and 33 days of seedling age in the central composite design. Brown rice yield per unit area at the stationary points were estimated 439 kg/l0a in the central composite design and 442 kg/l0a in the fractional factorial design. Considering the number of experimental treatment combinations, the central composite design was rather convenient in reducing the number of treatment combinations for similar information. It was more convenient for an experimenter to present the results from the central composite design than those from the fractional factorial design. Considering the optimum yields of brown rice per unit area at the stationary points being verified as saddle points in both designs. inter-heterogeneity of each of the factors should be avoided in setting up factors in pursuit of inducing unidirectional response of the factors to yield. Even though both the lower and higher levels in the central composite design being beyond the region of an experimenter's interest. they were considered highly valued in interpretation of the results. Conclusively. the central composite design was found to be more beneficial to optimize culture condition of paddy rice even with several levels of various factors were involved.

• Korean Journal of Medicinal Crop Science
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• v.5 no.2
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• pp.95-101
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• 1997

This study was conducted to investigate how a labor saving for conventional hand sowing and respond to major agronomic traits under different planting density in 1993 and 1994. Each trial was a randomized block split plot with row spacing as the main plots and hill spacing as subplots. Sowing rate appeared lower in 20 or 25cm hill spacing using machine seeder than in hand sowing. Sowing time required reduced more 121 hours per hectare in 60cm row, 20cm hill spacings using machine seeder than in hand sowing. Increasing row and hill spacings reduced number of seedling stand per unit $area(m^2)$. Both number of pods per plant and grain weight per plant and showed highly increase in wide planting. Best yield obtained in 60cm row, 20cm hill spacing using machine seeder. Accumulative mean air temperature was positively correlated with stem height, number of pods per plant and yield, otherwise accumulative rainfall was negatively correlated with ones. A highly significant negative correlation was showed between number of seedling stand per unit $area(m^2)$ and number of branches, number of pods per plant, grain weight per plant and yield. Yield was positively correlated with number of branches, number of pods per plant and grain weight per plant.

• 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.