To find out the optimum mixture ratio of ammonium and nitrate on rice plant, 4 rice varieties were examined during 14days after transplanting in hydroponics with the different ratio of ammonium to nitrate(100 : 0, 75: 25,50: 50, 25: 75 and 0: 100). The highest N uptake from solution and the maximum plant dry weight were 60~~70~% ammonium and 30~~40~% nitrate mixture treatment both in Japonica and Tongil type rice plants. And with the same varieties N-uptake and N use-efficiency were compared between 10.0 mM and 1.0 mM nitrogen using 70~% ammonium and 30~% nitrate for 24 days after transplanting. Rice plants absorbed more nitrogen(131~~145~%) in 10.0mM than 1.0mM treatment but accumulated N in rice plants were almost the same in both treatment. Among the tested rice cultivars, dry matter production and total accumulative nitrogen in rice plants were much high in Tongil type than japonica type rice cultivars. N-recovery ratios of rice plants from uptake N were 90.8-99.0~% in low concentration N solution(1.0 mM), but 69.4-81.7~% were observed in high concentration N solution(10.0 mM). It means that suppling low concentration N steadily will be better to prevent loss of N without reducing of growth in rice plants.

This study is to identify the physiological traits of submergence-tolerant varieties of rice plants (Oryza sativa L.) in Yeongnam area, southeastern part of Korea, where the reduction of rice yield due to submergence is remarkably severe. In the present study, two tolerant varieties of rice plants were selected from over 30 rice varieties grown in under a 10-day period. The tolerant varieties selected from a submerged paddy field. As a control, one intolerant variety of rice plant was chosen. Of the tolerant variety Samgangbyeo, rather than Haepyungbyeo, had a lower dissolved oxygen consumption and maintained a higher dry weight than the intolerant variety. The leaf photosynthetic rates (LPS) of the two tolerant varieties were significantly higher than that of the intolerant-variety after four days of submergence treatment. These results indicate that lower dissolved oxygen consumption in a limited pool is prevented by ethylene formation in the tolerant varieties, which may be a mechanism of submergence tolerance.

In plants, nitrogen is the major component for growth and development. Leaf growth is based on the division, elongation and maturation of cells, which are used for making of epidermis, mesophyll, bundle sheath, xylem, phloem and so on. Dynamics of these tissues with respect to nitrogen are required for better understanding. This experiment was conducted to evaluate effect of nitrogen on the elongation of epidermal and guard cell of two rice (Oryza sativa L.) varieties, Seoanbyeo and Dasanbyeo on May 2000 at Chungbuk national university in Cheongju. After transplaning the 20-day-old seedlings into a/5000 pots, the main characteristics related with cell elongation were investigated and evaluated. A maximum. leaf length reached at 7 or 8 days after emerging from the collar, and also the leaf elongation rates were greatly affected by the increase of N application rate. The initial and final cell length were about 17~mu~textrmm and 130~mu~textrmm , respectively. Cell divisions occurred within 1.0mm from leaf base. With die higher nitrogen application rate of 22 kg-N 10~textrma-1 , cell division per hour was greater 1.5 to 1.9 and 1.2 to 1.3 fold as compared to the N application rate of 0 and 11 kg-N 10~textrma-1 , respectively. Cell enlargement of epidermal and guard cell under higher N application rate (22kg-N 10~textrma-1 ) was finished within about 20 (Seoanbyeo) and 15 hours (Dasanbyeo), while it took much time, about 30 hours.

To identify the new source of breeding materials for rice salt tolerance, the salinity tolerance of thirty-four varieties was evaluated under 0.5% saline condition at seedling stage. The salinity score showed highly significant correlations to dry weight and dead leaf ratio. The tested varieties were classified into three groups by visual score, reduction ratio of dry weight, and dead leaf ratio. Eighteen varieties were classified as the highly tolerant group (salinity scores of 1.3-3.7), seven varieties were fallen into the tolerant group (salinity scores of 4.2-5.8), and others were susceptible (salinity scores of 6.7-9.0). In highly tolerant group, most indica varieties including Getu, Dikwee and Kuatic Putic, didn't exsert a panicle under the Korean climate. But six varieties, Xiangcho V, Annapuruna, HP 3319-2wx-6-3-1, Giza 175, and GZ 2447-S-17, GZ 4255-6-3 were suitable to the Korean climate, and their heading date (6-16, August) and culm length (65-78㎝) were similar to the Korean varieties. Accordingly, these varieties can be utilized as crossing materials for the salt tolerance in japonica rice.

A total of 206 paddy rice varieties was developed from 1933 to 2000 in Korea. However, genetic diversity and relationships among the varieties were not well characterized. The objectives of this study were to quantify genetic diversity and genetic relatio

간척지 논에서 고품질 쌀 생산을 위한 기초 자료를 얻고자 2001년 농업기반공사 김포간척지에서 9개 벼 품종의 수량과 단백질 함량 및 식미치의 관계를 검토한 결과는 다음과 같다. 1. 쌀 수량은 식미계에 의한 식미치와 고도로 유의한 부상관(r=-0.49** )을 나타내었다. 수량이 낮은 수라벼의 식미치가 가장 높았고 수량이 높은 대안벼와 진품벼는 식미치가 가장 낮았다. 2. 간척지 재배 백미의 단백질 함량은 모든 품종이 7.5% 이상으로 상당히 높은 편이었는데 이는 시비와 관개용수에서 많은 질소질비료가 공급된 결과로 보여졌다. 3. 김포간척지에 적합한 벼 품종은 수량성 면에서는 대안벼, 진품벼, 신동진벼이나 품질을 고려한다면 단백질 함량이 낮고 식미치가 높은 광안벼, 수라벼, 남평벼가 적합하다고 사료되었다.

본 연구는 쌀의 지속적 안정생산을 위한 기상재해 경감기술 개발의 일환으로 중부지역 벼 주요 장려품종의 포장 도복저항성 정도를 질소 보비와 다비 조건에서 검토하여 도복발생 상 습지역이나 질소과비 우려지역에서 벼 재배시 내도복성 품종의 선택 기준자료로 활용코자 수행한 결과를 요약하면 다음과 같다. 1. 질소다비시 도복저항성이 강한 품종은 오봉벼, 대진벼, 내풍벼, 농안벼, 일품벼의 5품종, 중 정도인 품종은 대안벼 등 14품종, 약한 품종은 진부벼 등 11품종이었다. 2. 질소다비시 도복정도별 직접효과가 큰 형질은 도복정도가 9로 심했던 품종은 간장과 중심고, 도복정도 5에서는 간장, 도복정도 3이하로 도복에 강했던 품종은 간장, 제3절간으로 나타났다. 3.쌀 수량은 질소보비에 대한 다비의 수량지수로 볼 때 조생종은 수량차가 5% 이내로 적었으나, 중생종 및 중만생종은 도복시기 및 도복저항성 정도에 따라 수량차가 크게 나타났다. 4. 이상에서와 같이 우리나라 중부지역 적응 벼 주요 장려 품종 중 도복저항성이 강한 품종을 도복발생 상습지역이나 질소 과비 우려지역에 재배함으로서 도복발생을 경감하여 쌀의 지속적 안정생산이 가능할 것으로 판단되었다.

남부지방 택사 앞작물에 적합한 조생종 벼 품종의 효율적인 선발을 위한 기초자료를 얻고자 우리나라 중산간 및 산간 고랭지용으로 개량된 조생종 벼품종 11품종을 공시하여 유전력, 표현형 상관, 유전상관, 환경 상관을 조사한 결과를 요약하면 다음과 같다. 1. 다수성이며 수량구성요소가 높은 조생종 벼로서는 Jinbubyeo가 가장 적합하였다. 2. 유전력은 수당입수(91.90), 정 조수량(69.88)에서 높았고 수장, 수수, 등숙 비율을 천립중은 중간정도였다. 3. 형질 상호간의 상관관계에서 정조수량은 간장, 수장, 수수, 수당입수, 등숙 비율을, 천립중과 고도의 유의차로 정의 상관을 보였다.