• KOREAN JOURNAL OF CROP SCIENCE
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• v.27 no.4
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• pp.385-397
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• 1982

The climatic impacts have been the environmental constraints with soil characteristics to achieve self sufficiency of food production in Korea. In this paper, the distribution and appearance of impacts and the changes in climatological status due to recent trend of early transplanting of rice are widely discussed to derive some countermeasures against the impacts, being focussed on cultural A long term analysis of the climatic impact appearances of the last 74 years showed that drought, strong wind, flood, cold spell and frost were the major impacts. Before 1970's, the drought damage was the greatest among the climatic impacts; however, the expansion and improvement of irrigation and drainage system markedly decreased the damage of drought and heavy rain. The appearance of cold damage became more frequent than before due to introduction of early transplanting for more thermophilic new varieties. Tongillines which were from Indica and Japonica crosses throw more attention to cold damage for high yields to secure high temperature in heading and ripening stages and lead weakness to cold and drought damage in early growth stage after transplanting. The plants became subject to heavy rain in ripening stage also. For the countermeasures against cold damage, the rational distribution of adequate varieties according to the regional climatic conditions and planting schedule should be imposed on the cultivation. A detoured water way to increase water temperature might be suggestable in the early growth stage. Heavy application of phosphate to boost rooting and tillering also would be a nutritional control method. In the heading and ripening stages, foliar application of phosphate and additional fertilization of silicate might be considerable way of nutritional control. Since the amount of solar radiation and air temperature in dry years were high, healthy plants for high yield could be obtained; therefere, the expansion of irrigation system and development of subsurface water should be performed as one of the national development projects. To minimize the damage of strong wind and rainfall, the rational distribution of varieties with different growing periods in the area where the damage occurred habitualy should be considered with installation of wind breaks. Not only vertical windbreaks but also a horizontal wind break using a net might be a possible way to decrease the white heads in rice field by dry wind. Finally, to establish the integrated countermeasures against the climatic impacts, the detailed interpretation on the regional climatic conditions should be conducted to understand distribution and frequency of the impacts. The expansion of observation net work for agricultural meteorology and development of analysis techniques for meteorological data must be conducted in future together with the development of the new cultural techniques.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.35 no.3
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• pp.239-247
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• 1990

In order to investigate the degree of grain shedding of red rices collected in Korea, breaking tensile and breaking bending strengths of 269 varieties; 82 Korean and 100 foreign red rices and 87 Korean cultivars including 26 native varieties, 30 Japonica-Indica hybrids and 31 Japonica type varieties, were measured at harvest time. Also, histological characteristics of abscission region between spikelet and pedicel were observed. The breaking tensile and breaking bending strengths of both Korean and foreign red rices were weaker than those of Japonica-Indica hybrids which were known as easily shedding varieties in Korea. Abscission layers were observed in the majority of Korean red rices except for 5 varieties, and those of all varieties belonging to both long grain types and 'Sare's were cracked completely at harvest time, while those of round grain types were not cracked except one variety. The breaking tensile and breaking bending strengths of the tested varieties having cracked abscission layer were weaker than those of non-cracked ones. Both strengths of breaking tensile and breaking bending were positively correlated with diameter of supporting zone and thickness of sclerenchyma tissue surrounding central vascular tissue of suporting zone at 0.1% significant level, respectively.

• The Korean Journal of Mycology
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• v.7 no.1
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• pp.13-73
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• 1979

These studies were conducted to investigate nutrient sources and supplementary materials of synthetic compost media for Agaricus bisporus culture. Investigation were carried out to establish the optimum composition for compost of Agaricus bisporus methods of out-door fermentation and peakheating with rice straw as the main substrate of the media. The incidence and flora of harmful organisms in rice straw compost and their control were also studied. 1. When rice straw was used as the main substrate in synthetic compost as a carbon source. yields were remarkably high. Fermentation was more rapid than that of barley straw or wheat straw, and the total nitrogen content was high in rice straw compost. 2. Since the morphological and physico-chemical nature of Japonica and Indica types of rice straw are greatly dissimilar. there were apparent differences in the process of compost fermentation. Fermentation of Indica type straw proceeded more rapidly with a shortening the compost period, reducing the water supply, and required adding of supplementary materials for producing stable physical conditions. 3. Use of barley straw compost resulted in a smaller crop compared with rice straw. but when a 50%, barley straw and 50% rice straw mixture was used, the yield was almost the same as that using only rice straw. 4. There were extremely high positive correlations between yield of Agaricus bisporus and the total nitrogen, organic nitrogen, amino acids, amides and amino sugar nitrogen content of compost. The mycerial growth and fruit body formation were severely inhibited by ammonium nitrogen. 5. When rice straw was used as the main substrate for compost media, urea was the most suitable source of nitrogen. Poor results were obtained with calcium cyanamide and ammonium sulfate. When urea was applied three separate times, nitrogen loss during composting was decreased and the total nitrogen content of compost was increased. 6. The supplementation of organic nutrient activated compost fermentation and increased yield of Agaricus bisporus. The best sources of organic nutrients were: perilla meal, sesame meal, wheat bran and poultry manure, etc. 7. Soybean meal, tobacco powder and glutamic acid fermentation by-products which were industrial wastes, could be substituted for perilla meal, sesame meal and wheat bran as organic nutrient sources for compost media. B. When gypsum and zeolite were added to rice straw. physical deterioration of compost due to excess moisture and caramelization was observed. The Indica type of straw was more remarkable in increase of yield of Agricus bisporus by addition of supplementing materials than Japonica straw. 9. For preparing rice straw compost, the best mixture was prepared by 10% poultry manure, 5% perilla meal, 1. 2 to 1. 5% urea and 1% gypsum. At spring cropping, it was good to add rice bran to accelerate heat generation of the compost heap. 10. There was significantly high positive correlation (r=0.97) between accumulated temperature and the decomposition degree of compost during outdoor composting. The yield was highest at accumulated temperatures between 900 and $1,000^{\circ}C$. 11. Prolonging the composting period brought about an increase in decomposition degree and total nitrogen content, but a decrease in ammonium nitrogen. In the spring the suitable period of composting was 20 to 25 days. and about 15 days in autumn. For those periods, the degree of decomposition was 19 to 24%. 12. Compactness of wet compost at filling caused an increase in the residual ammonium nitrogen. methane and organic acid during peak heating. There was negative correlation between methane content and yield (r=0.76)and the same was true between volatile organic acid and yield (r=0.73). 13. In compost with a moisture content range between 69 to 80% at filling. the higher the moisture content, the lower the yield (r=0.78). This result was attributed to a reduction in the porosity of compost at filling the beds. The optimum porosity for good fermentation was between 41 and 53%. 14. Peak heating of the compost was essential for the prevention of harmful microorganisms and insect pests. and for the removal of excess ammonia. It was necessary to continue fer mentatiion for four days after peak heating. 15. Ten species of fungi which are harmful or competitive to Agaricus bisporus were identified from the rice compost, including Diehliomyces microsporus, Trichoderma sp. and Stysanus stemoites. The frequency of occurrance was notably high with serious damage to Agaricus bisporus. 16. Diehliomyces microsporus could be controlled by temperature adjustment of the growing room and by fumigating the compost and the house with Basamid and Vapam. Trichoderma was prevented by the use of Bavistin and Benomyl. 17. Four species of nematodes and five species of mites occured in compost during out-door composting. These orgnanisms could be controlled through peakheating compost for 6 hours at $60^{\circ}C$.

• Journal of Life Science
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• v.28 no.3
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• pp.314-319
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• 2018

We analyzed QTLs for alkali-related digestion by using 120 population crossed Cheongcheong and Nagdong derived from anther culture (CNDH). The DNA markers located in the QTLs gene were selected and applied to existing cultivars. As a result of the investigation of the alkali decay degree, brown rice of Cheongcheong and Nagdong was 1.9 and 1.6, respectively, and the CNDH was $3.79{\pm}2.01$, and the distribution of variance was distributed to 7.0-1.0. The milled rice of Cheongcheong and Nagdong was 5.6 and 4.1, respectively. The mean of the CNDH was $4.86{\pm}1.55$, and the distribution of variance was distributed to 7.0-2.0. Variation distribution curves showed continuous variation that was close to non-normal distribution. In the QTLs analysis, qBRA2, qBRA6, and qBRA11 were mapped in 1-2 replications of brown rice. QHRA2-1, qHRA2-2, qHRA2-3, qHRA3, and qHRA8 were mapped in the first replication. QHRA2-1, qHRA2-2, qHRA2-3 and qHRA3 were mapped in the second replicates. And mapped to qHRA5 in 4 replicates. These were found on chromosome 2, 3, 6, 8 and 11, respectively. The phenotypic variations of qBRA2, qBRA6, and qBRA11 on the chromosomes of brown and milled rice were 1-9%. The polymorphism was analyzed for 12 types of the japonica type and six types of the indica type, based on the nine markers found in the QTLs analysis of alkali digestion. Chromosome 11, RM27258, was selected to determine the segregation ratio, which shows the difference in size by the band pattern. The results of this study will be used as basic data for the development of high-quality rice cultivars.

• Korean Journal of Weed Science
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• v.4 no.1
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• pp.52-61
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• 1984

Pot and laboratory tests were undertaken to investigate the influence of silicate fertilization on butachlor phytotoxicity to rice. Growth of rice seedlings at 150 ppm of $SiO_2$ was stimulated, while adverse effect was observed over 300 ppm of $SiO_2$ and growth reduction was enhanced with combination of butachlor and $SiO_2$ Rice growth in pot trial at 150kg/10a of silicate fertilization was not influenced by recommended amounts of butachlor and nitrofen, however, the growth of Seokwang byeo at 300kg/10a of silicate was markedly retarded by butachlor in the initial stage of growth. Growth reduction of Seokwang byeo caused by combined application of silicate and butachlor was recovered 50 days after herbicide application. Growth reduction from butachlor was not influenced by pH level and also degradation behaviors of butachlor in submerged soil was not altered by silicate fertilization. Adsorbed amount of butachlor on rice root was increased with addition of $SiO_2$ and its amount in Seokwang byeo was higher than that of Jinju byeo. Butachlor absorption by Seokwang byeo was accelerated by 150 ppm of $SiO_2$ applied simultaneously, but those effect was not encountered in Jinju byeo. Butachlor absorption of rice seedlings was also increased by 150 ppm of $K_2O$, while CaO hindered the absorption and $Na_2O$ had no effect on the absorption. Residual level of butachlor in Seokwang byeo treated with combined solution of butachlor and $SiO_2$ was continued higher than that with butachlor alone during 10 days after transplantation to culture solution.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.36 no.5
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• pp.394-406
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• 1991

It was proved that cold tolerance of rice plants at the young microspore stage was affected by water temperature and nitrogen application from the spikelet differentiation stage to the young microspore stage, and this mechanism could be explained in the point of view of pollen developmental physiology. The cold tolerance of rice plants at the young microspore stage was severely affected by water temperature (Previous water temperature) and nitrogen application(Previous nitrogen application) from the spikelet differentiation stage to the spikelet differentiation stage. Although the duration is only 10 days or so from the spikelet differentiation stage to the young microspore stage, these days are very important period to confirm the cold tolerance of rice plants at the young microspore stage. The higher previous water temperature up to $25^{\circ}C$ and the deeper previous water depth up to 10cm caused the more cold tolerance of rice plants. Water irrigation of 10cm before the cretical stage showed lower cool injury than that of water irrigation of 20cm during the critical stage. The preventive effect of cool injury by combined treatment of the deep water irrigation before and during the critical stage was not additive but synergistic. The cold tolerance of rice plants grown in previous heavy nitrogen level was rapidly decreased when nitrogen content of leaf blade at the young microspore stage was excessive over the critical nitrogen level. Nitrogen content of leaf blade at the changing point of cold tolerance was estimated as about 3.5% for Japonica cultivars and about 2.5% for Indica x Japonica cultuvars. It is considered that these critical nitrogen contents of leaf blade can be used as a index of the safe critical nitrogen level for the preventive practices to cool injury. It was summarized that increase of engorged pollens per anther by high previous water temperature resulted from the increase of number of differentiated microspores per anther, otherwise, the increase of engorged pollens by the decrease of previous nitrogen level was caused by the decrease of the number of aborted microspores per anther.

• Korean journal of applied entomology
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• v.17 no.1 s.34
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• pp.53-63
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• 1978

The object of this study is to clarify the varietal resistance to green leaf-and planthoppers and to evaluate the nature of the resistance to the insects in connection with the antibiosis. This study investigated the reaction of the 46 rice varieties to insects including recommended varieties of Korea. At seedling stage they were infested with second or third instar nymphs. The results were as follows. 1. The body weight of brown planthopper was increased more than 3 times on susceptible rice variety Mankyung at 15 days after infestation but only 2 times on resistant mudgo. 2. The mortaliy of the brown planthopper was significantly different between resistant and susceptible rice plant, showing 74 percents in resistant Mudgo while 31.2 percents in susceptible Mankyung at 15 days after caging. 3. Most of the rice varieties tested showed highly susceptible reaction to brown planthopper except Mudgo, KR 108-243-1 and HR 529-41-3-2 as resistant varieties, and Akamochi, Satominori, IR 24 and IR 8 as moderately susceptible ones. 4. In the test of varietal resistance to white-backed planthhopper, Mudgo, KR 108-243-1, KR 109-154-2 and HR 529-45-2 and HR 529-45-3-2 were resistant, and Suweon #82, Tongil, IR 8, Palkeum, Iri #309, Hokwang and Chukoku #31 were moderatly susceptible. 5. Most of the varieties tested were observed as highly resistant to green rice leafhopper, but Tongil, Suweon 82, IR 24, Milsung and Chukoku #31 were moderatly susceptible. 6. The new bred lines HR 108-243-1 are multi-resistant to brown planthopper, green rice leafhopper and White-backed planthopper, and some others showed moderate susceptibility.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.2
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• pp.200-208
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• 2010

The objectives of this study were to evaluate no-tillage cover crop cropping systems for organic farming in paddy. The experiment was performed at Ihyeon series (silt loam: 9.1% sand, 73.0% silt and 17.9% clay) which affected by different management practices. Planthopper population per 20 plant was significantly higher 65.3 for conventional tillage with chemical compounds (control) compared with 3.4~9.6 for no-tillage treatments (without rice straw or green manure, amended with rice straw, hairy vetch, rape, rye, and Chinese milk vetch). Also, disease severity of sheath blight was significantly higher 10.5% for control compared to 0.7~2.9% for no-tillage treatments. Four weed species, namely Monochoria vaginalis, Ludwigia prostrata, Rotala indica, and Aneilema keisak occurred in no-tillage paddy, whereas Monochoria vaginalis occurred in control only. The pH, available phosphate, and microbial biomass C in paddy were steeply decreased in response to submerging, but increased at first heading stage. Soil $NH_4$-N content at first heading stage was significantly higher in no-tillage treatments compared with control. The grain yield was significantly higher in 4.30 Mg $ha^{-1}$ for control than other treatments. Meanwhile, rice productivity was significantly higher in 2.69 Mg $ha^{-1}$ for no-tillage amended with Chinese milk vetch compared to other no-tillage treatments. The number of panicle per plant, grain number perpanicle, and percent ripened grain were highly related for increasing the yield of rice. These results show that Chinese milk vetch was optimum cover crop for organic farming in no-tillage paddy.

• Korean Journal of Agricultural Science
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• v.3 no.1
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• pp.11-16
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• 1976

This experiment was carried out to determine the most adequate type and period of nursery for the late seasonal cultivation of the new varieties of rice, Yusin and Josaengtongil. The results obtained are summarized as follows: 1. Semi-hot up-land nursery was much effective for the increase of the number of tillerings and the roots of rise seedlings compared with the semi-hot low-land nursery. The number of tillerings and roots was increased in 60 days seedlings compared with 50 or 60 days seedlings. 2. The abnormal heading has not appeared at the variety Yusin at all. The seedlings of Josaengtongil grown over 50 days at the semi-hot low-and nursery showed the abnormal heading, but the abnormal heading was not checked out at the seedlings of same variety grown for 60 days on the semi-hot upland nursery. 3. On the nursery not to cause the abnormal heading, earlier seeding was much effective for the hastening of the heading time and the hastening effect of heading time by earlier seeding was significantly greater at the variety Josaengtongil than Yusin 4. The number of ears per hill was significantly increased in the seedlings from the semi-hot up-land nursery compared with the semi-hot low-land nursery. 5. When the growing period of rice seedlings was not considered, the semi-hot up-land nursery resulted in higher yield of rice than the semi-hot low-land nursery. Considering the growing periods of rice seedlings, 40 days seedlings showed high yield at the semi-hot low-land nursery, however, at the semi-hot up-land nursery, 60 days seedlings showed higher yield of rice.

• 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.