Gibberellic acid did not affect ethylene production, whereas gibberellin biosynthesis inhibitors triggered ethylene production in dormant tubers. Gibberellic acid did not induce sprouting of dormant tubers, however, treatment of gibberellin biosynthesis retardants enhanced sprouting rates. Sprouting rate in ancymidol-treated tubers was highest among gibberellin biosynthesis retardants. Sprouting rate of tubers treated with ancymidol increased to 91.4~% . Batatasin-III content in GA3 treated tuber was increased in the highest concentration (30~mug~;I-1) . Tubers treated with mepiquat chloride, Batatasin-I was increased steadily, but contents of Batatasin-III and V showed dramatic decrease at the 1,000~mug~;I-1) concentration. This infers that gibberellin biosynthesis retardants play key roles in promoting breaking dormancy on dormant tubers of Chinese yam.

The induction of enzymes and the accumulation of their end products associated with self-defense mechanism in rice were investigated. When rice leaves were irradiated with UV light, activities of diterpene cyclase, phenylalanine ammonia-lyase (PAL), and cinnamic acid 4-hydroxylase (CA4H) were induced and rice phytoalexin, momilactone A was accumulated. The content of p-coumaric acid in rice leaves was closely correlated with self-defense or allelopathic potential against barnyardgrass. UV-challenged rice leaves gave rise to the inhibition of barnyardgrass growth

Barnyardgrass had relatively higher growth vigor at the earlier growth stage than inbred rice did, showing the 2 fold higher α -amylase activity during the periods of germination and large leaf area Expansion with high net photosynthetic rate at the earlier autotrophic stage, but it performed weak growth at the late growth stage. However, the hlybrid rice Shanyou 63 had significantly higher α -amylase activity and net photosynthetic rate than that of barnyardgrass, exhibiting heterosis for two physiologica1 traits during the germination (6~12 days) and autotrophic phase, respectively. Accordingly, hybrid rice, Shanyou 63, exhibited heterotic effect at the early growing stage when were presented with barnyardgrass. Shanyou 63 exhibited stronger tillering ability, faster leaf area expansion and higher net photosynthetic rate than those of barnyardgrass.

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.

To define the relations between endogenous GA levels and growth and flowering in short-day plant sorghum, growth retardant BX-112 was applied to two sorghum genotypes, wild-type and phytochrome B mutant (phyB-1), which grows faster and flowers earlier than the wild-type. BX-112 and GA3 were applied as a soil drench, and plant height, culm length, and date to floral initiation were investigated. Endogenous GAs contents were measured with GC-MS-SIM. BX-112 treatments inhibited shoot growth in both genotypes and drastically reduced GA1 and GA8 levels. With increasing BX-112 concentrations, GA1 concentrations declined linearly, but caused the accumulation of intermediates from GA12 to GA20 . This result implies that GA1 is the major active endogenous GA in shoot elongation in a short day plant sorghum. The inhibition of plant growth in both of wild type and phyB-1 by BX-112 was very similar, while BX-112 effects on floral initiation in two types of plants differed significantly. Floral initiation of phyB-1 was not affected by BX-1l2, but that of wild-type was delayed as BX-1l2 concentration increased. Because BX-112 treatment causes accumulation of biosynthetic intermediates between synthetic pathway from GA12 to GA20 and because phyB-1 is altered in GA metabolism in this same region of the early C13-hydroxylation pathway, BX-112 may fail to block flowering of phyB-1.

Three different male-sterile cytoplasmic lines and their common maintainer 'Zhenshan 97B' and two elite restorer lines were used to study cytoplasmic effects on agronomic trait manifestation per se under different nitrogen supply levels. The result showed that cytoplasmic effects could be modified by nitrogen environments. The cytoplasmic effect on grain yield under 150 kg N/ha varied depending on crosses, while it was significantly negative in most crosses under both 60 and 330 kg N/ha. The correlation and path-coefficient analyses suggested that it was expected to improve cytoplasmic effects through reducing maximum tillers and increasing the percentage of productive tillers, leading to increased productive tillers and higher yield in hybrid rice by the aid of cultural practice and genetic transformation. This study also revealed that the same cytoplasm in different combinations had differential effect under the same nitrogen environment, indicating that cytoplasmic effect was produced by interaction of nuclear genes with cytoplasm rather than cytoplasm per se. These results indicated the usefulness of evaluating diverse cytoplasmic sources in various nuclear genotypes bred for hybrid rice breeding program. The finding also suggested that negative cytoplasmic effect could be effectively overcome by elite restorer lines through the interaction of nuclear genes with female cytoplasm.

1. 다년생잡초 너도방동산이에 대한 수도품종 진흥과 조생통일의 재식거리를 달리하여 수도품종의 경합역을 검정하여 얻어진 결과를 요약하면 다음과 같다. 엽면적지수는 수도밀도가 감소될수록 작아지는데 조생통일은 수도와 너도방동산이의 밀도비가 2 : 1에서는 4.7이고 12 : 1에서는 3.5로 작아졌으며, 진흥은 2 : 1 에서 4.2이고 12:1에서 2.0으로 작아졌다. 2. 도복은 수도밀도가 감소될수록 증가되었으며 조생통일은 수도와 너도방등산이의 밀도비가 2 : 1에서 2.0이 12 : 1에서는 7.0으로 진흥에서는 2 : 1에서 3.3 이 12 : 1에서는 6.7로 각각 증가되었다. 3. 잡초의 건물중은 수도와 잡초와의 밀도비가 작아질수록 증가를 보였으며 조생통일은 2 : 1에서 185.3mg/m2 이 12 : 1에서는 338.1mg/m2 이 되었구 진흥은 2 : 1에서 176.7 mg/m2 이 12 : 1에서 423.6 mg/m2 으로 각각 증가되었다. 4. 수도와 잡초의 밀도비가 작아질수록 엽면적지수는 감소, 도복은 증가, 잡초의 수, 건물중이 크게 증가되므로 수도의 수량은 크게 감소되었는데 12 : 1의 밀도비에서 조생통일은 74%, 진흥은 58%의 수량감소를 보였다. 5. 수도와 잡초의 밀도비가 가장 낮은 12 : 1인 처리구에서 수량감소에 가장 크게 영향을 미친 것은 수량구성요소중 이품종 공히 단위면적당의 수수였으며 조생통일이 더 크게 영향을 받았다.수가 다른 지역에서 수집된 옥수수 보다 줬다. 10. 수집된 재래종 옥수수의 평균 입의 길이나 폭두께는 각각 0.82cm, 0.42cm. 0.78cm 이었다. 이들 이삭이나 입의 특성은 현재 장려 재배되고 있는 것의 그것보다 훨씬 뒤떨어지는 것을 본문에서 고찰했다.로 오히려 증가되는 경향을 보였다.고성장 시기에 유황 15% 첨가시비구가 125.7cm로서 대조구의 120.3cm보다 5.7cm가 길어 최장이었으며 엽수가 최고에 달했을 때의 유황 10% 첨가시비구가 109.7매로서 다른 처리보다 제일 많았고 대조구는 83.1매이었다. 6. 수수에 있어서는 대조구가 17.1이었고 이것에 비해 다른 처리구는 약간의 증가를 보이어 유황 및 Domomite처리구가 0.9~1.1개 정도의 증가를 보이었다. 그러나 수당립수는 대조구가 116.5립인데 비해 N.P.K.+S. 15% 처리구가 134.2립으로서 뚜렷한 차이를 보이었고 1000립중도 대조구가 24.5g인데 비해 N.P.K.+S. 10% 처리구가 27.7g로서 가장 무거워 많은 차이를 보이었다. 10a당 정조중은 대조구에 비하여 Dolomite처리구가 8.6%, 유황첨가구가 5.7~7.4% 증수되었음을 보이었다. 7. 식물체중의 조단백질 함량은 대조구, 5%, 10% 유황첨가구가 3.31~3.50%로서 비슷하였고 15% 유황첨가구는 3.94%, Dolomite첨가구는 5.38%였다. 아미노산도 15%유황첨가구와 Dolomite첨가구가 많이 함유되어 있었다. 현미중 조단백질은 15%유황첨가구가 10.14%로서 최고이었으며 10%유황첨가구와 Dolomite첨가구는 9.85%로서 다음이었다. 아미노산도 대조구의 현미에는 유황처리구보다 작았으며 유황처리구에서는 특히 Glutamic acid와 Lysine이 함유되여 있었다.ligraphy patterns were frequently used.의 증가를 나타냈다.". And the issu

다년생 잡초의 지하번식기관의 토양중 분포조사와 추경심도 및 AVIROSAN에 의한 다년생 잡초 가래 방제에 미치는 영향에 대하여 얻어진 예비결과를 요약하면 다음과 같다. 1. 너도방동산이와 올미의 괴경은 주로 0∼5cm의 깊이에 얕게 분포하여 있으나 가래의 인경과 올방개의 괴경은 각각 87%, 65%가 주로 10cm 이상의 깊이에 분포하였다. 2. 추경 20cm는 무경운, 무제초에 비하여 약 63%나 가래의 발생을 적게 하였다. 3. AVIROSAN 10a당 3kg 처리는 가래 방제에 특효하였으며 수량도 손제초 2회에 비하여 4% 증수되었다. 4. 보리짚 10a 당 250kg 처리도 가래의 발생억제는 물론 손제초 2회보다 1% 증수한 결과를 보였다.