• KOREAN JOURNAL OF CROP SCIENCE
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• v.36 no.2
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• pp.147-153
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• 1991

In order to clarify the varietal differences of grain shedding in 86 rice varieties with the diverse origin, a bundle of 10 panicles was fallen down on the bottom above 2m height, and several characters related to shattering were investigated. The ratio of grain shedding in the varieties from the Tongil types was the greatest (11. 29%), followed by the native and J aponica types (2.56, 0.17%). The breaking tensile and breaking bending strengths of the primary rachis-branch in the Tongil types were weaker than in the native and Japonica types with mean values of 217g and 20.5g, respectively. The fiber cells length of the primary rachis- branch in the Tongil types were shorter in the native and Japonica types. The ratio of grain shedding was significantly correlated with the breaking tensile and bending strengths of the primary rachis- branch, and fiber cell length.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.45 no.1
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• pp.26-31
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• 2000

This study was carried out to obtain the basic information for breeding cold-tolerant rice varieties with high yield-productivity through wide crosses between indica and japonica rice. Genetic analysis was conducted using 55 F$_1$s obtained from half-diallel crosses among eleven cultivars of various origin including indica and japonica rice. Screening for cold tolerance was done with cold-water irrigation after transplanting until ripening stage. Both general combining ability (GCA) and specific combining ability (SCA) effects were highly significant in all characters associated with dry matter accumulation at 30 and 50days after cold-water irrigation (DAC). The variance of GCA was much larger than that of SCA in plant height, shoot dry weight per plant (DWP), crop growth rate (CGR) and cold-water response index (CRI) of these characters except CRI of shoot dry weight per plant. The DWP, CGR and CRI of these characters of Gaochan 102, Tong88-7 and TR22183 were markedly higher than those of the others. GCA effects of these varieties on DWP, CGR and their CRI were also higher than those of the others, indicating that they are useful as promising parents for breeding cold-tolerant varieties. Analysis of genetic parameters for 11$\times$11 half-diallel F$_1$s revealed that inter-locus gene interaction were concerned in the expression of plant height at 50 DAC, CRI of DWP at 50 DAC, and CRI of CGR, and that intra-locus gene interaction for plant height and the other characters were partial dominance and over-dominance, respectively. Narrow-sense heritability (h$^2$$_{N}$) was the highest in plant height as 0.729, and the lowest in CRI of DWP at 30 DAC as 0.048, suggesting that selection for cold tolerance will be quite effective in case that the selection criterion is the performance itself.f.

• Korean Journal of Agricultural Science
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• v.9 no.2
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• pp.569-575
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• 1982

Mechanical properties of rice plants were tested to determine compressive force, bending force, tensile force and shear force for improvement of harvesting machines and for efficient utilization of rice culm during the proper harvesting period. Rice varieties used in this study were two Japonica varieties with Irri 348 and Jinju, and two $Indica{\times}Japonica$ hybrids with Seogwang and Taebaeg, which were grown in the standard fertilization field of Chungnam Rural Development Office. Also Jinju and Taebaeg were tested to elucidate the shearing characteristics which included shear force-strain relationship, shear force and shear energy according to the position from the ground level, the shearing angle to the rice culm, and the moisture content. 1. Compressive force, bending force, tensile force and shear force were higher In Japonica varieties than $Indica{\times}Japonica$ hybrids. 2. Shear force to overall culm length decreased progressively to upper positions in Jinju variety but a constant shear force was approximately showed between the ground level and the position of 21cm in Taebaeg variety. 3. Shear force and shear energy increased with increase of the cross sectional area, and the rates of increase were high in general up to the cross sectional area of $10mm^2$ and then they became dull very much. 4. Shear force and shear energy decreased with decrease of moisture content of rice culm after cutting up to the moisture content of 60% (w. b.) and then they did not change significantly.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.45 no.6
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• pp.361-365
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• 2000

This study was carried out to evaluate yearly variation and stability of yield and yield components of fifteen rice varieties. Yield stability and universal variety parameter of rice varieties were utilized for statistical model developed by Stroike, Grafius, and Finlay respectively. The lowest yearly variation based on coefficient of variation was found in Dasanbyeo for number of panicles/hill, in Jodongji for number of grains/panicle, in Yongmoonbyeo for ripened grain ratio, in Nagdongbyeo for 1,000 grain weight, and in Dasanbyeo for grain yield. Stability analysis by Stroike and Johnson's model revealed that Ilpumbyeo, Hwaseongbyeo, Dongjinbyeo in Japonica type, and And-abyeo and Dasanbyeo in Tongil type had the higher stability above average. Universal varieties analyzed by Grafius model were Ilpumbyeo, Dongjinbyeo, Hwaseongbyeo, Nagdongbyeo, and Jodongji in Japonica, and Dasanbyeo and Samgangbyeo in Tongil type. Damageum, Dongjinbyeo, Hwaseongbyeo and Ilpumbyeo in Japonica, and Dasanbyeo and Yongmoonbyeo in Tongil type were found to be highly stable as analyzed by Finlay ＆ Wilkinson's model. In conclusion, with reference to both grain yield and stability based on above three methods, Ilpumbyeo, Hwaseongbyeo, and Dongjinbyeo in Japonica, and Dasanbyeo in Tongil type were evaluated to be highly year-stable and high-yielding.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.49 no.4
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• pp.289-294
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• 2004

This study was carried out to investigate the antioxidative enzymes and isozymes between chilling-tolerant and -susceptible varieties at the booting stage under cold water stress $(13^{\circ}C)$ in japonica rice. Total SOD, CAT, POX, and GR activities on the basis of protein were found to be important factors to defend cold water stress. Especially, SOD and CAT activities showed distinctive differences between chilling-tolerant and -susceptible varieties. Chilling-tolerant varieties were higher than chilling-susceptible varieties for SOD and CAT activities. One of eight isozyme bands for SOD was a inducible isoform. Three isozymes for CAT and one isozyme for POX were closely correlated with defense to cold water stress. Total GR activities except Stejaree 45 on the basis fresh weight and POX were increased by cold water stress, but there was no difference between chilling-tolerant and -sus­ceptible varieties.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.21 no.1
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• pp.35-42
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• 1976

In Korea, two types of rice varieties are being cultivated widely, Japonica and Japonica-Indica cross. Generally speaking, the latter shows weak cold tolerance than the former and so brought about many problems in cultural practices. This study was conducted to investigate the effect . of various temperature conditions on rice seedlings growth, especially the contents of chlorophyll and the percentage of nitrogen. And the result obtained indicated the varieties of Japonica-Indica intend to weak cold tolerance than Japonica varieties.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.5
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• pp.335-340
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• 2002

To evaluate the efficiency of anther floating culture according to the maturing group, the varietal difference and classification of fifty varieties was conducted in N6 liquid medium containing 1mg $l^{-1}$ NAA, 0.25 mg $l^{-1}$ kinetin. The efficiency of callus induction was widely ranged from 0 to 113.4%, but the mean callus induction was not significantly different among maturing groups. The efficiency of anther floating culture showed the highest variation in early-maturing group among three maturing groups. The varieties with the best callus induction were Sambaegbyeo and Jinbuolbyeo, while the recalcitrant variety was Obongbyeo in early-maturing group. The efficiency of plant regeneration showed the highest trends in late-maturing group among three maturing groups. The fifty varieties were classified into three groups (distance=0.78) by cluster analysis based on the callus formation and plant regeneration. Group including only two varieties, Shinunbongbyeo and Sambaegbyeo had the excellent androgenic efficiency, and the medium efficiency of Group was included thirty-six varieties. Whereas twelve varieties, including three Tongil varieties were fell into the bad efficiency of Group. Especially, Tongil varieties containing Japonica rice, Obongbyeo were the recalcitrant genotypes for the anther floating culture.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.27 no.4
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• pp.439-451
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• 1982

In fact, rice cultivation technique from 1962 to 1970 was very slight, but this technique from 1970 to now was remarkably developed in Korea, it was due to development of high fretilizer responsive and lodging resistant variety, Tongil; ie. Ind. ${\times}$ Japonica remote-cross rice variety. The main factors of this development is as follow: Firstly the most farmer (more than 90%) used newly developed seedling growth method; polyethylene film covered protected nursery bed. Secondly date of transplanting (middle or late part. of May) was earlier 10-15days than before 1970. Thirdly new varieties were highly lodging resistant at high fertilizer level $(N-P_2O_5-K_2O:15-9-11 kg/l0a)$. However, this level is 50% increased one than it for Japonica varieties. At forth planting density increased up to 75-80 hills per $3.3m^2$. Added to these factors, farm labor shortage and wage increase due to economic development gave a chance for introduction of transplanting machine to farmer in 1977. It's use increased for 100, 800 ha in 1981. The most of farmers are using herbicides and weed control system dependoing on wood composition has been established and disseminated to farmer.

• Journal of the Korean Society of Food Science and Nutrition
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• v.13 no.4
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• pp.372-376
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• 1984

Calorie, mineral content and amino acid composition of four japonica, seven $j{\times}indica$ and one waxy milled rice were analyzed. No significant differences in calorie, mineral content and amino acid composition were found between japonica and $j{\times}indica$ rice varieties. Only the variation of methionine among varieties was noticed. The most limiting amine acid of milled rices was lysine.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.28 no.2
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• pp.151-163
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• 1983

This study was conducted to investigate the responses to photoperiod of some Korean rice cultivars at four levels of the day length, 10, 12, 14 and 16 hours. Generally the days to heading were reduced in the short day length. Japonica varieties seemed to have shorter basic vegetative growth phase and, were more sensitive to day length, while Japonica crossed Indica varieties showed longer basic vegetative growth phase and, were less sensitive to day length. All tested varieties could be classified into 19 ecotypes based on the periods of the basic vegetative growth phase and the sensitivity to day length.