• KOREAN JOURNAL OF CROP SCIENCE
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• v.31 no.3
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• pp.311-317
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• 1986

To obtain the basic informations on the variation of rice grain shattering under different environmental conditions, several experiments were carried out from 1982 to 1985. The degree of grain shattering was significantly differed depending upon the harvesting time after heading in some rice varieties. It appeared that the ratio of grain shattering was greatly affected by the drying period after harvesting; the ratio of grain shattering of sun-dried seeds for 6 days after harvesting was higher than those of the just harvested seeds. Grain shattering was increased at high level of nitrogen and decreased with delay in transplanting date. Yearly differences in grain shattering was more clearly recognized in easy-shattering varieties in comparison with those of non-shattering varieties. Rice grain shattering also increased by the low temperature treatment (l7/15$^{\circ}C$, day/night) at booting stage, 5 to 11 days before heading. A rice variety, Milyang 23, belong to easy shattering group was more pronounced at the low temperature condition with shading. In general, it was always possible to classify the cultivar differences between easy-shattering and non-shattering groups regardless of any environmental condition. Thus results suggested that rice grain shattering will be largely governed by genetic factors.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.36 no.5
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• pp.429-444
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• 1991

Cold stress influence plant growth through a wide range of growth characters. Adverse effects of low temperature to plant growth come from results of colligative and complex physiological responses to cold stress. To evaluate more exactly cold tolerance of crop plant, it is needed to observe physiological changes induced by cold stress and to analyze relationships between intraspecific variations in physiological factors related to cold tolerance and the extent of cold tolerance in the field. Therefore, the composition and unsaturation ratio of fatty acids in phospholipid, a constituent of membrane, the transition-temperature in respiratory activity of mitochodria, the chlorophyll fluorescence as a factor related to photosynthesis were investigated in rice plant and data on these factors were compared with the degree of cold tolerance obtained in the field experiment. Also, effects of hardening and Mn++ treatment were evaluated as a method to reduce chilling injuries. The unsaturation ratio of fatty acids, whether rice plants were grown in a natural condition or under the chilling stress, was higher in the cold- tolerant varieties and was significantly correlated with the degree of cold tolerance (1-9) observed in the field experiment. And it was also increased by chilling treatment or hardening treatment, due to a reduction in palmitic acid content and an increase in linolenic acid content. The transition-temperature of respiratory activity of mitochodria isolated from etiolated rice seedlings ($25^{\circ}C$, two week-grown in the dark), was correlated with the degree of cold tolerance in the field, cold -tolerant varieties showing a lower transition-temperature. It was not influenced by growth stages. The intensity of chlorophyll fluorescence was highly correlated with the degree of cold tolerance, cold-tolerant varieties having a higher fluorescence intensity. By foliar application of Mn, the transition-temperature of respiratory activity was lowered as much as 0-2$^{\circ}C$ in all tested varieties. Soil application of Mn induced more significant effect in cold-susceptible varieties with a possibility of reducing chilling injuries. On the whole, there were high correlationships among the degree of cold tolerance, the unsaturation ratio of fatty acids in phospholipid, the transition- temperature of respiratory activity and chlorophyll fluorescence except for a few varieties. The transition- temperature of respiratory activity appeared to be negatively correlated with the unsaturation ratio of fatty acids. and the chlorophyll fluorescence to be positively correlated with the unsaturation ratio. This implies that these physical and physiological factors were very closely related to cold tolerance and can be used as an effective index of the evaluation of cold tolerance of crop plant. But other factors as well as three factors discussed above are needed to be considered colligatively and altogether with a systematic analysis for the more exact evaluation of cold tolerance. in rice cultivars. in rice cultivars.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.28 no.3
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• pp.285-290
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• 1983

Two methods were tested to establish the cropping period for rice cultivation using the meteorological data. The Hanyu-Uchijima method was based on the normal average temperature to select the earliest possible transplanting date (ETD), the earliest heading date (EHD), the optimum heading date (OHD) and the latest maturing date (LMD). The probability method was based on the temperature occurrence probability. The cropping period based on the probability method gave higher stability than H-U method for year variability. The ETD by the probability of 75 to 90 percents was May 12 to 22 for northern part of Korea, May 15 to 25 for east coastal area and May 4 to 16 for southern part, respectively. In Chuncheon area, the rice varieties requiring more than 1700 degree-days from transplanting to heading might not be appropriate due to low temperature condition and those requiring 1900 degree days were not allowable in Kangreung area. The OHD was July 30 to August 8 in northern part of the country and August 11 to 16 in southern part for Tongil varieties which demand higher temperature than common Japonica varieties. The OHD for Japonica varieties were 5 to 7 days later than Tongil varieties. The LMD was September 30 to October 2 in northern part, October 13 to 14 in east costal area and October 7 to 14 in southern part, and was earlier than the first frost date.

• Korean journal of applied entomology
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• v.22 no.4 s.57
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• pp.277-282
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• 1983

Number and percentage of diseased area of leaf blast lesions formed on different leaf location were mostly distributed from the flag leaf(n-1) to the 3rd leaf from the top(n-3) in Tongil line rice varieties and on the 2nd leaf from the top(n-2) in Japonica type rice varieties. Especially leaf lesions of Nopung which was more susceptible to leaf blast among Ton1 line rice varieties were mostly distributed on flag leaf. Relation between the degree of lesion distribution and level of fertilizer was more clear with an increase of fertilizer quantity. Leaf blast lesions of rice varieties were generally distributed from the flag leaf to the with leaf from the top but mainly those at flag leaf and the 2nd leaf from the top were found to be most responsible for inoculum source of panicle blast after booting stage. Increase of the conidia formation was resulted from fluctuation of temperature$(24^{\circ}C\~16^{\circ}C)$ in low temperature range after booting stage and many inoculum sources were supplied on panicles until the end of September without impeding dispersal from leaf blast lesions as an inoculum source of panicle blast.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.65 no.3
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• pp.241-247
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• 2020

Sesame is typically a temperature- and day length-sensitive plant, as its flowering is promoted under high temperature and shorter day length conditions. The experiment carried out in the present study revealed that day length influenced sesame flowering to a much greater extent than temperature. The degree of day length influence differed depending on the sesame variety. Days from sowing to flowering was negatively correlated with yield-related characteristics such as stem length, capsule number per plant, 1,000 seed weight, and seed weight per 10a. In cases where the period from sowing to flowering was longer and flowering date was later, the reproductive growth period was shorter during maturity. Analysis of the effects of temperature and day length on seed yield production revealed that temperature was a much more influential factor than day length. However, day length was more influential than temperature under low temperatures, such as 22℃. All varieties apart from Ansan were shown to be primarily influenced by temperature. Sesame varieties were grouped in view of optimal seed sowing time through principal components analysis. The Poongsung and Sungboon varieties favored early sowing under low temperatures and short day lengths. The DT45, Poongsung, 90 days, Ansan, and Sungboon varieties favored late sowing under high temperatures and long day lengths. The Yangbaek and Arum varieties could be sown both early and late.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.25 no.4
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• pp.59-65
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• 1980

An attempt was made to survey soybean cultivars that were nonsensitive to the photoperiod for selection as possible breeding materials for wide area adaptable varieties. Fifty-five cultivars were subjected to different day length conditions. The number of days from sowing until flowering was shortened under short day length conditions, and late varieties tended to be more sensitive to day length than early varieties. The response to day length of the tested cultivars might be divided into three groups; low, intermediate and high degree, by their accelerated rate of flowering. Especially four varieties in the low responding group, Gembokin, Wirth, Wayne and Pi.54613 were identified to be nonsensitive to day lengths, that is, neutral varieties. They also showed little variation in morphological characteristics under different day length conditions.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.44 no.2
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• pp.171-175
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• 1999

Morphological alteration of floral organ development in rice affected by chilling stress was examined. Three varieties of rice were grown under natural conditions and subjected to 12$^{\circ}C$ for 3 or 6 days starting from the ineffective tillering stage, before heading stage and returned to natural condition. Headings were delayed by a 6 day chilling treatment. After heading the panicles were collected and examined for any possible alteration in floral organ development. It appears that there were some differences in sensitivity to chilling stress and degree of injury depending on treatment stages and variety. Chuchungbyeo was the most frequent in producing abnormal flowers among the three varieties examined. Meiosis stage was shown to be the most vulnerable to chilling stress in both Chuchungbyeo and Ilpumbyeo and young panicle differentiation stage was the frequent stage to alter flower development in response to chilling stress only in Chuchungbyeo. It was confirmed that abnormalities occurred in pollen due to chilling stress is a major factor leading to low yield, but to some extent the alterations in carpel development may playa certain role in determining a total yield in response to chilling stress at the reproduction stage in rice. There were abnormalities like extra stigmata, extra lemma, double ovary as well as abnormal anther formation in response to chilling stress. Further studies of the phenocopy observed in rice floral development may be useful for an understanding of the resistance against chilling injury during reproductive stages in rice.

• Korean Journal of Organic Agriculture
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• v.11 no.3
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• pp.75-90
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• 2003

A total of 192 Korean landraces were investigated for the comparison of each other as useful germplasm to organic farming and examined correlation between quantitative traits. Almost Korean landraces were classified into medium-heading variety and average days from seeding to heading was 111.1 days. Plant height and culm length were longer about 20∼40cm than general Japonica cultivar. Average width of leaf blade and average length of panicle were 1.3cm and 22.4cm, respectively, Average number of panicles per plant was 10.0 and almost varieties showed low tilling habit. Average length/width ratio of brown rice was 1.7 and several varieties were long grain type and average 1,000 grain weight was 21.6g. In correlation coefficient among quantitative traits, positive significant correlations were observed between culm length and leaf width, days from seeding to heading, but negative correlations were observed between days from seeding to heading and 1000 grain weight. 27.1% of Korean landraces showed weak and lodging degree in culm strength and 3.6% of total varieties showed purple margin on leaf blade and leaf sheath. In leaf blade angle and flag leaf angle, erect type was 46.9% and 10.9%, respectively. 24.0% of total varieties showed the slow and late degree of leaf senescence. The rate of awned type, waxy type and brown seed coat were 74.5%, 20.3% and 4.2%, respectively. The color of stigma, spikelet, apiculus and awn showed diverse color such as white, brown, red and purple.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.23 no.2
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• pp.1-24
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• 1978

To obtain basic information on the breeding of early maturing, short culm naked-barley varieties, the following 10 varieties, Ehime ＃ 1, Shikoku ＃42, Yamate hadaka, Eijo hadaka, Kagawa ＃ 1, Jangjubaeggwa, Baegdong, Cheongmaeg, Seto-hadaka and Mokpo ＃42 were used in diallel crosses in 1974. Heading date, culm length and grain yield per plant for the parents, $F_1's$ and $F_2's$ of the 10X10 partial diallel crosses were measured in 1976 for analysis of their combining ability, heritability and inheritance. The results obtained are summarized below; 1. Heritabilities in broad sense for heading date, culm length and grain yield per plant were 0.7831, 0.7599 and 0.6161, respectively. Narrow sense heritabilities for heading date were 0.3972 in $F_1$ and 0.7789 in $F_2$ and for culm length 0.6567 in $F_1$ and 0.6414 in $F_2.$ These values suggest that earliness and culm length could be successfully selected for in the early generations. Narrow sense heritability for grain yield was 0.3775 in $F_1$ and 0.4170 in $F_2.$ 2. GCA effects of the $F_1$ and $F_2$ generations for days to heading were high in the early direction for early-heading varieties, while for late-heading varieties the GCA effects were high in the late direction. Absolute values for GCA effects in $F_1$ were higher than in $F_2.$ SCA effects of the $F_1$ and $F_2$ generations were high in the early-heading direction for Shikoku ＃ 42 x Mokpo ＃ 42, Ehime ＃ 1 x Yamate hadaka, Shikoku ＃ 42 x Yamate hadaka and Shikoku ＃42 x Eijo hadaka. 3. The GCA effects for culm length in the $F_1$ and $F_2$ generations for tall varieties were high in the tall direction while short varieties were high in the short direction. Absolute values for the GCA effects in $F_1$ were higher than in $F_2.$ SCA effects were high in the short direction for the combinations of Mokpo ＃ 42 with Ehime ＃ 1, Yamate had aka and Eijo hadaka. 4. The GCA effects for grain yields per plant in the $F_1$ and $F_2$ generations for varieties with high yields per plant were high in the high yielding direction, while varieties with low yields per plant were high in the low yielding direction. Absolute values of the $F_1$ GCA effects were higher than the $F_2$ effects. The combinations with high SCA effects were Mokpo ＃ 42 x Shikoku ＃ 42, Mokpo ＃ 42 x Seto hadaka and Mokpo ＃ 42 x Cheongmaeg. 5. Mean heading dates of the $F_1$ and $F_2$ generations were earlier than those of mean mid-parent. Mean heading date of the $F_1$ generation was earlier than the $F_2$ generation. Crosses involving early-heading varieties showed a greater $F_1, $ mid-parent difference than crosses involving late-heading varieties. 6. Heading date was controlled by a partial dominance effect. Nine varieties excluding Mokpo ＃ 42 showed allelic gene action. Ehime ＃ 1, Shikoku ＃ 42, Kagawa ＃ 1 and Mokpo ＃ 42 were recessive to the other tested varieties. 7. The $F_2$ segregations of the 45 crosses for days to heading showed that 33 cosses were of such complexity that they could not be explained by simple genetic inheritance. One cross showed a 3 : 1 ratio where earliness was dominant. Another cross showed a 3 : 1 ratio where lateness was dominant. Four other crosses showed a 9 : 7 ratio for earliness while six crosses showed a 9 : 7 ratio for lateness. 8. Many transgressive segregants for earliness were found in the following crosses; Eijo hadaka x Baegdong, Ehime ＃ 1 x Seto hadaka, Yamate had aka x Kagawa ＃ 1, Kagawa ＃ 1 x Sato hadaka, Shikoku ＃ 42 x Kagawa ＃ 1, Ehime ＃ 1 x Kagawa ＃ 1, Ehime ＃ 1 x Shikoku ＃ 42, Ehime ＃ 1 x Eijo hadaka. 9. Mean culm length of the F, and F. generations were usually taller than the mid-parent where tall parent were used. These trends were high in the short varieties, but low in the tall varieties. 10. Culm length was controlled by partial dominace which was gonverned by allelic gene(s). Culm length showed a high degree of control by additive genes. Mokpo ＃ 42 was recessive while Baegdong was dominant. 11. The F_2 frequency for culm length was in large part normally distributed around the midparent value. However, some combinations showed transgressive segregation for either tall or short culm length. From combinations between medium tall varieties, Ehime ＃ 1, Shikoku ＃ 42, Eijo hadaka and Seto hadaka, many short segregants could be found. 12. Mean grain yields per plant of the F_1 and F_2 generations were 6% and 5% higher than those of mid-parents, respectively. The varieties with high yields per plant showed a low rate of yield increase in their F_1's and F_2's while the varieties with low yields per plant showed a high rate of yield increase in their F_1's and F_1's. 13. Grain yields per plant showed over-dominnee effects, governed by non-allelic genes. Mokpo ＃ 42 showed recessive genetic control of grain yield per plant. It remains difficult to clarify the inheritance of grain yields per plant from these data.

• Journal of The Korean Society of Grassland and Forage Science
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• v.21 no.3
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• pp.129-136
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• 2001

The alpine grassland vegetation at the northwest slope of Mt. Paektu were investigated by Penound- Howard's cover-degree method. The floristic composition of the alpine grassland from 2,100m altitude to the top of mountain were 35 species, 1 subspecies, and 6 varieties, and most of the plants were short p e r e ~ i a l herbs and shrubs. The dominant species of the vegetation distributed along to altitude were Rhododendron aureum (2,100-2,20Om), Dryas octopetala var. asiatica(2,200-2,30Om), Dryas octopetala var. asiatica(2,300-2,40Om), Rhododendron aureum- Rhododendron redowskianum(2,400-2,50Om), and Rhododendron redowskianum(2,500- 2,58Om), respectively. Characteristics of the shrub plants which settled in alpine grassland showed uniform low height(3-15cm), creeping stem and evergreen leaf. Life form of the plants were 29 species of Hemicryptophyte, 8 species of Chamaephyte, 1 species of Geophyte, and 5 species of Phanerophyte. (Key words : Alpine grassland, Mt. Paektu, Altitude, Dominant, Life form)