In order to overcome the recrystallization embrittlement and irradiation embrittlement of Mo, which are major problems for its fusion applications, internally nitrided Mo alloys were prepared by a novel multi-step internal nitriding. Neutron irradiation was performed in the Japan Material Testing Reactor (JMTR). After irradiation, nitrided Mo alloys exhibited ower ductile-brittle transition temperature than irradiated TZM. These results suggested that multi-step internal nitriding was effective to the improvement in the embrittlement by irradiation. Transmission electron microscope observation revealed that TiN particles precipitated by nitriding acted as a sink for irradiation-induced defects.

벼멸구선충(Agamermis unka)은 우리나라에서 벼멸구와 흰등멸구의 중요한 천적이다. 따라서 1992년부터 1998년까지 그리고 2001년 우리나라의 논에서 벼멸구선충의 분포를 조사하였다. 1992년부터 1998년까지 고성과 경상남도농업기술원, 남해, 통영의 예찰포에서 월동 벼멸구선충의 밀도를 조사한 결과 지역과 연도별로 차이가 있었다. 2001년 5개도 30개 시.군 예찰포를 대상으로 벼멸구선충의 월동 밀도를 조사한 결과, 전남의 장흥과 해남, 경남의 남해, 진주, 산청, 사천, 고성, 통영, 의령, 창원, 김해 지 역에서만 분포가 확인되었다. 그리고 경남 남해지 역 이 1,045마리/㎥로 밀도가 가장 높았고, 진주의 경상남도 농업기술원, 고성 예찰포에서는 각각 947마리와 395마리/㎥가 발견되어 다른 지역의 예찰포보다 높았다. 벼멸구선충의 밀도는 무방제구가 살균제처리나 살충제처리구에 비하여 높았으나 유의성은 없었다. 경남 지역 19개 시군의 예찰포에서 벼 수확 후의 벼멸구선충 밀도를 2001년 가을에 조사한 결과는 고성, 진주, 남해, 사천 지역에서만 분포가 확인되었는데, 밀도는 남해지역이 692마리/㎥로 가장 높았다.

본 연구는 벼멸구, 벼흰잎마름병, 벼줄무늬잎마름병에 저항성인 자포니카 복합내병충성 품종을 조기에 확보하고자 약배양을 수행하여 목표 저항성 유전자 조합의 우량 고정계통을 개발하고 육성 과정 중에 발생할 수 있는 문제점을 파악하여 병해충 저항성 육종사업에 반영하고자 수행하였다. 벼흰잎마름병과 벼줄무늬잎마름병에 저항성인 우량 계통 HR26234- 12-1-1과 벼멸구, 벼흰잎마름병, 벼줄무늬잎마름병에 저항성인 SR30071-3-7-23-6-2-1-1을 인공 교배한 F1을 약배양하여 213개 고정계통을 육성하였다. HR26234는 Xa3+xa5, Stvb-i, SR30071은 Bph18, Xa4, Stvb-i를 가지고 있는 것으로 확인되었다. 이들 유래 약배양 계통들은 모두 Stvb-i를 가지고 있었고, Bph18+Xa3, Bph18+Xa4, Bph18+Xa3+xa5, Bph18+Xa4+xa5, bph18+Xa3, bph18+Xa4, bph18+Xa3+ xa5과 bph18+Xa4+xa5의 조합이 확인되었다. 약배양 집단에서 xa5+Bph18(또는 bph18)+Stvb-i 조합이 발생하지 않았고 Bph18 보유 계통이 bph18 보다 적게 발생하는 등 segregation distortion이 발생하였다. Bhp18을 보유하며 벼멸구에 저항성인 계통들이 감수성인 계통들에 비해 간장이 컸다. 선발된 Bph18+Xa4+xa5+Stvb-i 조합의 계통은 단간이면서 벼멸구, 벼흰잎마름병, 벼줄무늬잎마름병에 저항성을 나타내었으나, 낮은 수량성과 일부 불임의 발생, 단간임에도 도복에 안정적이지 못한 특성을 나타냈다. 병해충에 대한 저항성 육종사업에서 약배양을 활용하여 조기에 육종 목표를 달성하고자 할 경우에 segregation distortion이 발생하여 편의 된 변이가 발생할 수 있고, 저항성 유전자 도입 시 linkage drag에 의해 예기치 못한 열악형질 특성이 나타날 수 있음을 고려하여 신중하게 목표에 접근하여야 할 것으로 생각한다.

‘'Hwangkeumnuri’' is a japonica rice variety developed and registered by the rice breeding team of Honam Agricultural Research Institute, NICS, RDA in 2006. This variety was derived from a cross between ‘'Milyang 165’' (Junambyeo) with good quality and high yield and HR14732-B-67-2-3 with multi-disease resistance. This variety has about 125 days growth duration from transplanting to harvesting in west-southern coast, Honam and Youngnam plain of Korea. It is about 76 cm in culm length and tolerance to lodging. In reaction to biotic and abiotic stresses, it shows resistance to blast, bacterial blight pathogen from K1 to K3 and stripe virus, but susceptible to other major diseases and insect pests. The milled rice of ‘'Hwangkeumnuri’' exhibits translucent, relatively clear non-glutinous endosperm and midium short grain. It has similar amylose content of 18.9% and lower protein content of 6.2%, and good palatability of cooked rice compared with ‘'Nampyeongbyeo’'. The milled rice yield performance of this variety is about 5.74 MT/ha in local adaptability test for three years. ‘'Hwangkeumnuri’' would be adaptable to west-southern coast, Honam and Yeongnam plain of Korea.

"Gopumbyeo" is a new japonica rice variety developed and registered by the rice breeding team of National Institute of Crop Science, RDA in 2004, which was derived from a cross between a line SR15225-B-22-1-2 which has good eating-quality and high yield potential and a line SR15140-58-2-2-3 which has lodging and disease resistances. This variety has medium heading date of Aug. 13, medium culm length of 78 cm and tolerance to lodging. It has also relatively semi-erect pubescent leaf blades and slightly tough culm with good canopy architecture. Gopumbyeo has a bit less number of tillers per hill and more spikelets per panicle than Hwaseongbyeo. It shows less sensitivity to premature heading in delayed transplanting of 50-day old seedlings. It showed longer delay of heading date but higher spikelet fertility than Hwaseongbyeo when exposed to cold stress. This variety shows delayed leaf senescence and considerable tolerance to viviparous germination during ripening. It shows moderate resistance to leaf blast, and bacterial blight, but susceptibility to stripe virus and insect pests. The milled rice of Gopumbyeo exhibits translucent, clear non-glutinous endosperm and medium short grains. It shows similar amylose content of 19.6%, and gelatinization temperature, and better palatability of cooked rice compared to Hwaseongbyeo. The milled rice yield of this variety is about 5.48 MT/ha at ordinary culture in local adaptability test for three years. Gopumbyeo would be highly adaptable to the central lowland and mid-southern mountainous areas of Korea.

"Samkwangbyeo" is a new japonica rice variety developed and registered by the rice breeding team of National Institute of Crop Science, RDA in 2003, which was derived from a cross between good quality, high yielding line Suweon361 and a disease resistant line Milyangl01. This variety has about 129 days duration from seeding to heading in central lowland and mid-mountainous areas. It is about 87 cm in culm length and moderately tolerant to lodging. It has also erect pubescent leaf blade and slightly tough culm with good canopy architecture. Samkwangbyeo has the same number of tillers per hill and spikelets per panicle as those of Ilpumbyeo. It shows less sensitivity to premature heading by lately transplanting of 50-day old seedlings. It is slightly less tolerant to cold stress in terms of both heading delay and spikelet fertility than those of Ilpumbyeo. It shows delayed leaf senescence and considerable tolerance to viviparous germination at ripening stage. It shows moderate resistance to leaf blast, bacterial blight, and stripe virus, but susceptibility to insect pests. The milled rice of Samkwangbyeo exhibits translucent, relatively clear non-glutinous endosperm and medium short grain. It has similar amylose content of 18.3% and similar gelatinization temperature, and good palatability of cooked rice compared to Ilpumbyeo. The milled rice yield of Samkwangbyeo is about 5.69 MT/ha at ordinary culture in local adaptability test for three years. Samkwangbyeo would be highly adaptable to central lowland and mid-southern mountainous areas of Korea.