The changes of the amino acid content including proline and protein content in response to NaCl treatment were investigated in between the salt-resistant variety CI5309 and salt-susceptible variety IR28 of rice. The amino acid contents such as -aminoapid

To determine whether the enhanced UV-B causes oxidative stress, and to test the relationship between plant growth response and biochemical defense response to UV-B, two soybean plants, Keunolkong, a highly UV-B susceptible cultivar, and Danyeubkong, a less UV-B susceptible cultivar, were subjected to the enhanced UV-B [daily dose : 0.06 (control) and 11.32 (enhanced UV-B) kJ m^-2 ; UV-B_BE] for 3 weeks. Contents of malondialdehyde and total carotenoid were increased in Keunolkong compared with Danyeubkong by UV-B. In control plants, ascorbate level of Danyeubkong was 3 times higher than that of Keunolkong. The ratio of dehydroascorbate/ascorbate was highly increased in Keunolkong by UV-B. The activities of antioxidative enzyme such as superoxide dismutase, ascorbate peroxidase, monodehydroascorbate reductase and glutathione reductase were increased in both cultivars by UV-B. This results indicate that enhanced UV-B caused oxidative stress in both two cultivars, especially in Keunolkong. Susceptibility of two soybean cultivars to UV-B is closely related to the levels of antioxidants such as carotenoid and ascorbate.

The experiment was conducted to determine the effects of enhanced UV-B on growth and differential responses among cultivars in soybean. The soybean cultivars subjected to enhanced UV-B irradiation at daily dose of 11.32 kJ m^-2(UV-B_BE) revealed that the growth was significantly depressed. Plant height, leaf number, leaf area and dry weight were inhibited by UV-B irradiation showing differential responses among cultivars used. Danyeubkong seems to be less sensitive to the enhanced UV-B irradiation, while Keunolkong more sensitive. Reduction of chlorophyll content was also found significantly greater to Keunolkong. Specific leaf weight, an index of leaf thickness, and flavonoid content known as UV-absorbing compounds were significantly increased in Danyeubkong by UV-B, but those in the other cultivars were not significantly affected. The results indicated that there are cultivar differences in the growth and physiological responses to the enhanced UV-B irradiation and specific leaf weight and UV-absorbing compounds in the leaves were highly related to the sensitivity of soybean by UV-B irradiation.

대두의 돌연변이육종을 함에 있어서 돌연변이기의 효율적인 선발법을 확립하기 위하여 M1세대의 초장 및 주당종자수와 M2세대의 돌연변이 출현과의 관계 그리고 M1 식물체의 키메라에 대해 조사한 결과를 요약하면 다음과 같다. 1. 30kR의 감마선을 종자에 처리하였을 때 M1초장의 분포는 무처리에 비해 45-68% 감소되는 개체가 전체의 63.7%를 차지하였으며 이 범위에 속하는 집단내에서 엽녹소변이는 71.4%, 가시적 형태변이가 62.3%를 차지하였다. 2. M1주당종자수는 6-15개인 개체가 전체의 58.9%를 차지하였고 이때 엽녹소변이는 55.3%, 가시적 형태변이는 63.4%를 차지하였다. 3. M1 집단에서 초장과 주당종자수는 통계적으로 유의한 정의 상관이 있었다. 4. M1의 초장의 장해가 심하고 주당종자수가 적을 수록 M2에서 가시적 형태변이의 출현율이 높았으며 반대로 엽녹소변이는 초장장해가 적고 주당종자수가 많을수록 변이출현율이 높은 경향이었다. 5. 변이가 일어난 M2 family의 변이의 sector 크기는 M1주당종자수 적을수록 크게 나타났다. 6. 엽녹소변이를 대상으로 M1식물체의 꼬투리별로 돌연변이의 출리양상을 보면 식물체의 부위별로 일정한 경향이 없이 임의로 발생하였다. 7. 대두의 돌연변이육종을 효율적으로 수행하기 위해서는 종자에 고선량의 방사선을 처리할 것과 M1의 주당종자수가 적은 개체를 수확하여 M2에서 집단으로 양성할 것을 추천한다.