• KOREAN JOURNAL OF CROP SCIENCE
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• v.27 no.4
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• pp.371-384
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• 1982

Highly cold tolerant varieties are requested not only at high latitute cool area but also tropical high elevated areas, and the required tolerance is different from location to location. IRRI identified 6 different types of cold tolerance required in the world for breeding purpose; a) Hokkaido type, b) Suweon type, c) Taipei 1st season type, d) Taipei 2nd season type, e) Tropical alpine type and, f) Bangladesh type. The cold tolerance requested in Korea is more eargent in Tongil group cultivars and their required tolerance is the one such as the physiological activities at low temperature are as active as in Japonica group cultivars at least during young seedling stage and reproduction stage. With conventional Japonica cultivars, such cold tolerant characters are requested as short growth duration but stable basic vegetative growth, less sensitive to high temperature and less prolonged growth duration at low temperature. The methods screening for cold tolerance were developed rapidly after the Tongil cultivar was reliesed. The facilities of screening for cold tolerance, such as, low temperature incubator, cold water tank, growth cabinet, phytotron, cold water nursery in Chuncheon, breeding nursery located in Jinbu, Unbong and Youngduk, are well established. Foreign facilities such as, cold water tank with the rapid generation advancement facilities, cold nurseries located in Banaue, Kathmandu and Kashimir may be available for the screening of some limitted breeding materials. For the reference, screening methods applied at different growth stages in Japan are introduced. The component characters of cold tolerance are not well identified, but the varietal differences in a) germinability, b) young seedling growth, c) rooting, d) tillering, e) discolation, f) nutrition uptake, g) photosynthesis rate, h) delay in heading, i) pollen sterility, and j) grain fertility at low temperature are reported to be distinguishable. Relationships among those traits are not consistent. Reported studies on the inheritance of cold tolerance are summarized. Four or more genes are controlling low temperature germinability, one or several genes are controlling seedling tolerance, and four or more genes are responsible for the pollen fertility of the rice treated with cold air or grown in the cold water nursery. But most of those data indicate that the results may come out in different way if those were tested at different temperature. Many cold tolerant parents among Japonicas, Indicas and Javanicas were identified as the results of the improvement of cold tolerance screening techniques and IRTP efforts and they are ready to be utilized. Considering a) diversification of germ plasm, b) integration of resistances to diseases and insects, c) identification of adaptability of recommending cultivars and, d) systematic control of recommending cultivars, breeding strategies for short term and long term are suggested. For short term, efforts will be concentrated mainly to the conventional cultivar group. Domestic cultivars will be used as foundation stock and ecologically different foreign introductions such as from Hokkaido, China or from Taiwan, will be used as cross parents for the adjustment of growth durations and synthsize the prototype of tolerances. While at the other side, extreme early waxy Japonicas will be crossed with the Indica parents which are identified for their resistances to the diseases and insects. Through the back corsses to waxy Japonicas, those Indica resistances will be transfered to the Japonicas and these will be utilized to the crosses for the improvement of resistances of prototype. For the long term, efforts will be payed to synthsize all the available tolerances identified any from Japonicas, Indicas and Javanicas to diversify the germ plasm. The tolerant cultivars newly synthsized, should be stable and affected minimum. to the low temperature at all the growing stages. The resistances to the diseases and insects should be integrated also. The rapid generation advancement, pollen culture and international cooperations were emphasized to maximize the breeding efficiency.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.2
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• pp.217-223
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• 2010

This study was conducted to reclassify Dongsong series based on the second edition of Soil Taxonomy and to discuss the formation of Dongsong series distributed on the lava plain at Cheolweon in Korea. Morphological properties of typifying pedon of Dongsong series were investigated, and physico-chemical properties were analyzed according to Soil Survey Laboratory Methods Manual. The typifying pedon of Dongsong series has brown (7.5YR 4/2) silty clay loam Ap horizon (0-16 cm), brown (7.5YR 4/2) silty clay loam BA horizon (16-22 cm), brown (7.5YR 4/2) silty clay Bt1 horizon (22-50 cm), reddish brown (5YR 5/4) silty clay Bt2 horizon (50-92 cm), and brown (7.5YR 4/3) silty clay loam Bt3 horizon (92-120 cm). It occurs on lava plain derived from baslt materials. The typifying pedon has higher bulk density than 0.90 Mg $m^{-3}$. That can not be classified as Andisol. But it has an argillic horizon from a depth of 22 to more than 120 cm, and a base saturation (sum of cations) of less than 35% at 125 cm below the upper boundary of the argillic horizon. It can be classified as Ultisol, not as Andisol or Alfisol. It has aquic conditions for some time in normal years in one or more horizons within 50 cm of the mineral soil surface, redoximorphic features between a depth of 25 cm, and a depth of 40 cm from the mineral soil surface, and redox concentrations, and 50%or more redox depletions with chroma of 2 or less in the matrix within the upper 12.5 cm of the argillic horizon. Therefore it can be classified as Aquult. It has episaturation, and keys out as Epiaquult. It has 50% or more chroma of 3 or more in one or more horizons between a depth of 25 cm from the mineral soil surface, and a depth of 75 cm. It can be classified as Aeric Aquult. Dongsong series have 35%or more clay at the particle-size control section, and have mesic soil temperature regime. Therefore they can be classified as fine, mesic family of Aeric Epiaquults, not as fine, mesic family of Typic Epiaqualfs. The Quarternary volcanic activities occurred in Jeju Island, Ulrung Island, Baekryeong Island, Cheolweon area, and Mt. Paekdu et al. in the Korean Penninsula. Most of them belong to the central eruption type, but Cheolweon area may be of the fissure eruption type. Dongsong series occur on Cheolweon lava plains derived from basaltic materials. Most soils distributed in Jeju Island, and derived from mainly pyroclastics are developed as Andisols. But Dongsong series distributed in Cheolweon lava plains which have a relatively dry climate and derived from basaltic materials are developed as Ultisols.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.34 no.s02
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• pp.45-65
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• 1989

The Korean peninsular having the complexity of the photography and variability of climate is located within passing area of a lots of typhoon occurring from the southern islands of Philippines. So, there are various patterns of wind and flooding damages in paddy field occuring by the strong wind and the heavy rain concentrated during the summer season of rice growing period in Korea. The wind damages to rice plants in Korea were mainly caused by saline wind, dry wind and strong wind when typhoon occurred. The saline wind damage having symptom of white head or dried leaves occurred by 1.1 to 17.2 mg of salt per dry weight stuck on the plant which was located at 2. 5km away from seashore of southern coastal area during the period(from 27th to 29th, August, 1986) of typhoon &Vera& accompanying 62-96％ of relative humidity, more than 6 m per second of wind velocity and 22.5 to 26.4$^{\circ}C$ of air temperature without rain. Most of the typhoons accompanying 4.0 to 8. 5m per second of wind and low humidity (lesp an 60％) with high temperature in the east coastal area and southen area of Korea. were changed to dry and hot wind by the foehn phenomenon. The dry wind damages with the symptom of the white head or the discolored brownish grain occurred at the rice heading stage. The strong wind caused the severe damages such as the broken leaves, cut-leaves and dried leaves before heading stage, lodging and shattering of grain at ripening stage mechanically during typhoon. To reduce the wind damages to rice plant, cultivation of resistant varieties to wind damages such as Sangpoongbyeo and Cheongcheongbyeo and the escape of heading stage during period of typhoon by accelerating of heading within 15th, August are effective. Though the flood disasters to rice plant such as earring away of field, burying of field, submerging and lodging damage are getting low by the construction of dam for multiple purpose and river bank, they are occasionally occurred by the regional heavy rain and water filled out in bank around the river. Paddy field were submerged for 2 to 4 days when typhoon and heavy rain occurred about the end of August. At this time, the rice plants that was in younger growing stage in the late transplanting field of southern area of Korea had the severe damages. Although panicles of rice plant which was in the meiotic growing stage and heading stage were died when flooded, they had 66％ of yield compensating ability by the upper tilling panicle produced from tiller with dead panicle in ordinary transplanting paddy field. It is effective for reduction of flooding damages to cultivate the resistant variety to flooding having the resistance to bacterial leaf blight, lodging and small brown planthopper simultaneously. Especially, Tongil type rice varieties are relatively resistant to flooding, compared to Japonica rice varieties. Tongil type rice varieties had high survivals, low elongation ability of leaf sheath and blade, high recovering ability by the high root activity and photosynthesis and high yield compensating ability by the upper tillering panicle when flooded. To minimize the flooding and wind damage to rice plants in future, following research have to be carried out; 1. Data analysis by telemetering and computerization of climate, actual conditions and growing diagnosis of crops damaged by disasters. 2. Development of tolerant varieties to poor natural conditions related to flooding and wind damages. 3. Improvement of the reasonable cropping system by introduction of other crops compensating the loss of the damaged rice. 4. Increament of utilization of rice plant which was damaged.

• Korean Journal of Weed Science
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• v.7 no.2
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• pp.186-199
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• 1987

This study was carried out to investigate the growth of Korean lawn grass (Zoysia japonica Steud.), penncross bentgrass (Agrostis palustris Huda) and seaside bentgrass (Agrostis spp.) under application of 21 pre- and post-emergence herbicides and the weeding effect of 14 annual and 4 perennial weeds with them for the purpose of the systematic chemical weed control in turf. The results obtained were as follows; 1. Napropamide, napropamide + triclopyr and benefin were safe for Korean lawn grass and two kinds of bentgrasses when they were treated at 4 and 25 days after transplanting of turfgrasses. Simazine, lenacil and bentazon inhibited the growth of bentgrasses, but not Korean lawn grass. 2. The preemergence application of simazine, benefin and napropamide + simazine showed excellent control for Digitaria sanguinalis, Cyperus amuricus, Chenopodium album, Portulaca oleracea and Centipeda minima. Lenacil was excellent for control of all the tested weeds except Chenopodium album, napropamide excellent for them except Cyperus amuricus and Portulaca oleraces, and bentazon good for them except Digitaria sanguinalis. When simazine was treated with either napropamide or triclopyr at preemergence of weeds, weeding effect increased without inhibition of lawn growth. 3. The postemergence application of mecoprop, bentazon, benefin + dicamba and benefin + mecoprop was safe to bentgrasses. All the tested postemergence herbicides except simazine + atrazine did not inhibit the growth of Korean lawn grass. 4. Other postemergence herbicides mecoprop and triclopyr were excellent for the control of Echinochloa crusgalli and those except benefin and mecoprop excellent for Kummerovia striata. Digitaria sanguinalis was controlled by treating with all the tested post emergence herbicides and Cyperus amuricus controlled only by bentazon. 5. The growth rates of bentgrasses treated with simazine, lenacil and napropamide + simazine were lower than that of hand-weeded check, and those of benefin, bentazon, napropamide, napropamide + triclopyr, stomp, bensulide and triclopyr were higher than that one when applied at spring season. Korean lawn grass growth appeared to be good under application of all the tested preemergence herbicides at spring. Lanacil and bentazone showed poor control of Echinochloa crusgalli, and bensulide showed poor control of Erigeron canadensis. Also, napropamide and bentazon were not good for Kummerovia striata control. However, at the respective rates of all the tested herbicides, these three weeds were greatly controlled by 85-100% of weeding effect. 6. At the application of autumn season, bentazon, napropamide, pendimethalin, benefin, napropamide + triclopyr, bensulide and triclopyr seemed to be safe against three kinds of turfgrasses. But simazine, napropamide + simazine inhibited the growth of bentgrasses except Korean lawn grass. In terms of weed control performance, triclopyr was poor for controlling Echinochloa crusgalli and bentazon and stomp for Poa annua, napropamide, benefin and bensulide for Stellaria medico. Stellaria uliginosa and Cerastium caespitosum were well controlled by all the tested preemergence herbicides. 7. Korean lawn grass was safe when paraquat and glyphosate were treated at the dormanant season of turfgrass. These herbicides showed excellent controll of Poa annua but poor control of perennials in order of Trifolium repens < Miscanthus sinensis < Calystegia japonica < Artemisia asiatica. 8. In field test, all of 19 herbicides seemed to be safe when treated at Korean lawn grass. All of 10 preemergence herbicides were excellent for controlling annual weeds, but poor for perennial ones. All of 9 postemergence herbicides showed a excellent control for broad-leaf weeds.