Information on genetic diversity and relationships among the breeding materials is essential to the plant breeders in theefficient improvement of crops. The objective of this study was to determine the consistency between two methods of measuringped) and

This experiment was conducted to investigate the variation of nitrogen use efficiency, nitrogen uptake efficiency, physiological utilization efficiency and their relationships with growth characteristics in the 28 Korean rice cultivars. Nitrogen use efficiency of 28 rice cultivars was 47.74, nitrogen uptake efficiency was 0.71, and physiological utilization efficiency was 68.76 in average. Nitrogen use efficiency of rice cultivars had low variation ranged from 44.09 to 51.91, but nitrogen uptake efficiency were relatively high variation from 0.51 to 0.90, and physiological utilization efficiency was from 51.71 to 94.26. The high efficient group in nitrogen uptake efficiency whose value was calculated above 0.80 included Daeanbyeo, Seojinbyeo, Ansungbyeo, Dongjinbyeo, and Hwaanbyeo, while the low efficient group with below 0.60 was Kwanganbyeo, Sampyeongbyeo, Soorabyeo, and Hwasungbyeo. Hwasungbyeo, Sampyeongbyeo, Soorabyeo for physiological utilization efficiency were more efficient cultivars, while Daeanbyeo, Seojinbyeo, Ansungbyeo were less efficient cultivars. Nitrogen uptake efficiency had positive correlation coefficients between dry matter weight of plant (0.842** ), leaf area index (0.761** ), and leaf nitrogen content (0.599** ), respectively. Therefore, the dry matter weight of rice plant and leaf area index was important characters to evaluate nitrogen uptake efficiency in rice cultivars. Also, more efficient cultivar in nitrogen uptake had higher chlorophyll meter value, which was appeared dark green color.

암흑처리가 라맥의 개화유기에 대한 일연의 시험 결과는 다음과 같다. 1. 저온과 암흑처리의 효과 저온효과에 대하여 반응이 뚜렷한 4가지 라맥품종에 대한 암흑처리의 효과는 모두 저온효과와 동일하고 5℃ 하에서 80~90%의 개화유기를 보였으며 추파형이며 단일춘화에 민감한 Kobinkadagi 품종을 제외하고 나머지 3 품종은 고온(25℃ )에서도 저온효과에는 미치지 못하나 71~80%의 개화유기를 보였다. 2. 암흑처리기간의 효과 Hashinhadaka 품종의 암흑처리기간에 따른 개화효과는 45일처리가 제일 높았고, 5℃ 인 경우에는 30일과 45일사이에서 차이가 없었으나 25℃ 인 경우에는 3가지 수준사이에 유의적인 차이가 있었다. 3. 암흑처리전의 묘령에 의한 효과 2가지 온도수준에 있어서 개화효과는 5℃ 인 경우에는 묘령에 관계없이 모두 개화하였으나 25℃ 인 처리구에서는 묘령이 증가할수록 개화율이 감소하였다. 4. 저온암흑 교호처리효과 저온과 암흑의 전기간(45일) 처리에 의한 개화율은 100%와 60%로써 유의적 차이를 나타내었고 초기와 후기의 15일간씩의 교호처리효과는 91%, 중기 15일간의 교호효과는 92%의 개화율을 보였으므로 저온과 암흑의 작용기구는 상이한 것으로 사료된다.