새로 조성된 간척농지의 토양개량을 위하여 새만금간척지에서 2007년부터 2011년까지 4년 동안 녹비작물 (여름철 : 세스바니아, 제주재래피, 수수×수단그라스, 겨울철 : 귀리, 호밀, 보리) 재배 및 시용이 토양이화학성에 미치는 영향을 조사하여얻은 결과는 다음과 같다.1. 녹비작물의 바이오매스 생산량은 평균 9.7~15.0ton/ha이었으며, 이 중에서 수수×수단그라스의 생산량이 가장 많았다.2. 녹비작물의 재배와 시용으로 토양유기물 함량이 1.3에서6.0g/kg로 매년 평균 1.2g/kg씩 증가하였다.3. 녹비작물의 재배와 토양환원에 의해 토양의 용적밀도가1.44에서 1.24Mg/m3로 감소하였다.4. 수수×수단그라스와 호밀의 이어짓기가 토양 용적밀도 감소에 가장 효과적이었고, 세스바니아 재배는 토양 질소함량 증가에 가장 효율적이었다.이상의 결과로 미루어 볼 때 간척지에서의 녹비작물 재배및 시용은 토양의 비옥도 요인을 일부 개선시킴으로써 간척농지 개량에 기여할 수 있을 것으로 기대된다. 앞으로 신간척지에서의 유기물과 관련된 다각적인 연구가 필요할 것으로 생각된다.

The present study describes carbohydrate metabolism, macro-element utilization and antioxidant defenses in response to an ozone dose (100 ppb, 8d) in two rice varieties. Tolerant (cv. Jinpumbyeo) and sensitive (cv. Chucheongbyeo) varieties of rice were grown in growth chamber for 30 days after sowing. Concentrations of chloroplast pigments and non-structural carbohydrates as well as activity of antioxidant enzymes were determined to evaluate the resistance against ozone stress. Ozone caused the decrease in chlorophyll a and carotenoid contents, and also resulted in faster decomposition of non-structural carbohydrate in leaf blade and leaf sheath. The contents of nitrogen and potassium in leaves were visibly decreased in cv. Chucheongbyeo with an increase in ozone exposure, but not in cv. Jinpumbyeo. Enzymatic antioxidants against ROS in both varieties responded in the order of POD, SOD and CAT, and their capacity was stronger in cv. Jinpumbyeo.

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.

Rice (Oryza sativa L.) plants were cultivated to examine changes in antioxidative defence mechanism induced by elevated ozone levels. Catalase activities in tolerant Jinpumbyeo and susceptible Chucheongbyeo under ozone fumigation were reduced at 5 hrs and 3 hrs after ozone fumigation, respectively. With the increased ozone supply, peroxidase activity in Jinpumbyeo was steadily enhanced whereas in Chucheongbyeo it was not changed. Four SOD-isozymes were detected by NBT staining of native-PAGE. Two isozymes of them were obviously induced by ozone supply, particularly in Jinpumbyeo. The continuous ozone fumigation increased remarkably putrescine levels in leaves whereas it did not affect the levels of spermidine and spermine. In this study, it was implied that ozone in cell inhibits strongly diamine oxidase and thus promotes ethylene biosynthesis which will cause the senescence in rice plants.