실험 I. 질소의 시비량을 달리 하였을 때 출수기에 있어 실비의 효과 및 전엽처리에 따른출수후의 각엽위별 엽신이 등숙 및 수량에 미치는 영향을 알고저 포장시험을 한바 그 결과는 다음과 같다. 1. 질소시비에 따른 1주평균 수수 및 1수당 경화수는 질소의 시비량이 많을수록 증대되었으나 등숙율, 제현비율 및 현미천립중은 질소시비량이 많을수록 저하되었다. 2. 출수기 실비시비에 따른 등숙률 및 현미천립중은 표준구보다 질소시비량이 많을수록 증대되었으며 정조중은 통계적인 유의차는 인정할 수 없으나 수치적으로 증대되었다. 3 전엽처리에 따른 등숙율, 정조중, 현미천립중 및 제현비율은 전엽의 정도가 클수록 현저히 저하되었다. 4. 엽위별 존치엽수의 조합에 따른 등숙율, 정조중현미천립중 및 제현비율은 엽신 1매를 존치하였을 때는 L1(지엽)>L2>L3>L4순으로 저하되었으며, 엽신 2매를 존치하였을 때는 상위엽과 조합될수록 증대되었다. 그리고 엽신 3매를 존치하였을 때도 같은 경향을 보였다. 5. 전엽처리에 따라 엽위별 엽신수가 감소될 경우에는 존치엽면적이 넓고 엽신건물중과 엽신질소함량이 증대될 때에 등숙률, 정조중, 현미천립중 및 제현비율이 증대되었다. 6. 시비량의 증대는 존치엽수와 관계없이 등숙률 및 현미천립중을 저하시켰으나, 실비의 시용은 이와는 반대의 결과를 보였다. 정조수량은 기비 및 추비량의 증대에 따라 증대되는 경향을 보였으며 실비의 효과는 존치엽수가 적을 경우에는 많을 경우보다 저하되었다. 7. 엽신이 차지하는 등숙률 및 현미수량에 대한 생산효과는 50% 이상이었으며 천립중은 10%에 불과하였다. 질소의 시비량의 증가에 따라 등숙율 및 천립중에 대한 엽신의 영향은 증대되었다. 기비량의 증가에 따라 현미중에 대한 엽신의 영향은 증대되었으나 수전기의 추비량이 증가될수록 그 영향은 저하되었다. 8. 엽위별 엽신이 등숙율, 현미중 및 천립중에 미치는 생육효과는 L1(지엽)>L2>L3>L4순이었으며 질소의 시비량이 많을수록 L1 과 L2 의 생산효과가 증대되는 경향을 보였다. 시험 II. 질소의 시비시기를 달리 하였을 때 전엽처리에 따른 출수후 엽위별 엽신이 등숙 및 수량에 미치는 영향을 알고저 포장시험을 한바 그 결과는 다음과 같다. 1. 1주당 평균 수수는 기비로부터 출수전 22일까지 시비된구와 분시된구에 있어서 증대되었으며 경화수는 출수전 36일부터 15일까지 시비된구가 증대되었다. 등숙율은 기비구로부터 출수전 15일까지는 무비구보다 저하되었으며 출수전 8일 이후에 시비된 구는 증대되었다. 가장 저하된 구는 출수전 29일구였다. 정조수량은 출수전 29일부터 22일 시비구가 가장 증대되었다. 현미천립중은 출수전 22일부터 8일까지의 시비된구가 다소 높았다. 2. 전엽처리에 따른 등숙율, 정조중, 현미천립중 및 정현비율은 전엽의 정도가 클수록 모두 현저히 저하되었으며 처리간에 고도의 유의차를 보였다. 3. 엽위별 존치엽수와 그의 조합에 따른 등숙율 정조중, 현미천립중 및 제현비율은 엽신 1매가 존치되었을 때는 L1(지엽)>L2>L3>L4순으로서 상위엽이 존치될수록 증대되었다. 엽신 2매시는 상위엽과 조합되었을 때 등숙율, 정조중 및 제현비율이 증대되었으며 현미천립중의 증대에는 지엽이 가장 크게 작용한 것 같았다. 엽신 3매를 존치하였을 때도 상위엽과 조합된 것일수록 증대되었다. 4. 전엽처리에 따라 엽위별 엽신수가 감소될 경우 엽면적 엽신건물중 및 엽신질소함량과 등숙율 및 정조중간에는 정의 상관을 보였으나 현미천립중간에는 시비시기에 따라 일정한 경향을 보이지 않았다. 5. 시비시기가 출수기에 가까울수록 전엽에 의한 등숙율 및 천립중은 저하되었으며 존치엽수가 적어질수록 그 경향은 증대되었다. 출수기 이후의 추비는 존치엽수의 증대에 따라 등숙율 및 천립중을 증대시키며 존치엽수가 적을 경우에는 출수기에 가까운 시기에 시비가 정조수량을 증대시켰다. 6. 시비시기에 따른 각기관별 생산효과는 등숙율에 있어서는 시비시기가 늦어질수록 엽신의 생산효과가 크며 무비구에 있어서는 엽신과 간의 생산효과가 동일하였다. 현미수량에 대한 생산효과는 시비시기에 구애됨이 없이 간의 생산효과는 50%이상을 찾 하였으며 무비구에 있어서는 그 경향이 더욱 증대되었다. 현미천립중은 간에 의하여 지배되며 엽신의 영향은 근소하였다. 7. 엽위별 엽신이 등숙율, 정조중 및 현미천립중에 미치는 생산효과는 시비시기가 늦어짐에 따라 상위엽일수록 생산효과가 증대되는 경향을 보였다. 전생육기간을 통하여 분시된구는 등숙율 및 정조수량에 있어서는 지엽과 2위엽이 거의 같은 정도였으나 현미천립중에 있어서는 지엽이 전엽의 생산량의 60%이상을 차지하였다.

Experiment I: A field experiment was conducted in an attempt to find the effect of top-dressing at heading time in different levels of nitrogen application and of different positioned leaf blades formed by the treatment of leaf defoliation at heading time on the ripening and the yield of rice. The results obtained are as follows: 1. Average number of ears per hill and average number of grains per ear in different levels of nitrogen application were increased as the amount of nitrogen applied was increased. while the rate of ripened grains the yield of rough rice and the weight of 1, 000 kernels of brown rice were decreased respectively as the amount of nitrogen applied was increased. 2. The rate of ripened grains and the weight of 1.000 kernels of brown rice in different levels of nitrogen, top-dressing at heading time were larger than those in control and increased. The yield of rough rice although statistically significant differences were not recognized, were numerically increased. 3. The rate of ripened grains, the yield of rough rice, the weight of 1, 000 kernels of brown rice and the rate of hulling in different treatments of leaf defoliation were remarkably decreased as the degree of leaf-defoliation became larger. 4. The rate of ripened grains, the yield of rough rice, the weight of 1, 000 kernels of brown rice and the rate of hulling in different combinations of number of remained leaves positioned differently, formed the order of L1(flag leaf)>L2>L3>L4 when only one leaf blade was remained, and were increased as the positions of leaves were higher when two leaf blades. were, remained. 5. In case of decrease in the number of leaf blades positioned differently, by the treatment of leaf. defoliation, rate of ripened grains, the yield of rough rice, the weight of 1, 000 kernels of brown rice and the rate of hulling were increased as the area of remained leaves became larger and the nitrogen content of a leaf blade was increased. 6. There was a tendency that the increase in the amount of fertilizer application made the rate of ripened grains and the weight of 1, 000 kernels of brown rice reduced in any number of remained leaf blades, but the application of top-dressing at heading. time resulted in the reverse tendency. The yield of rough rice showed a tendency to be increased as the amount of basal dressing and top-dressing increased and for the application of top-dressing at heading time, the yield of rough rice was less at the smaller number of those. 7. The productivity effect of the rate of ripened grains and the yield of brown rice covered by leaf blades was more than 50 per cent and that of the. weight of 1, 000 kernels of brown rice was not more than 1.0 percent. As the amount of nitrogen application increased the. effect of leaf blades on the rate of ripened. grains and the weight of 1, 000 kernels of brown rice was increased. The effect of leaf blades on the weight of brown rice was increased as the amount of basal dressing-application, but the effect was decreased as the amount of top-dressing at heading time increased, 8. The productivity effects of different positioned leaf blades on the rate of ripened grains, the yield of rough rice and the weight of 1, 000 kernels of brown rice were in order of L1(flag leaf)>L2>L3>L4 the productivity effects of L1 and L2 had a tendency to be increased as the amount of nitrogen applied was increased. Experiment II: A field experiment was done in order to disclose the effect of the time of nitrogen application on yield component and the effect of different positioned leaves formed by leaf defoliation at heading time on the rate of ripened grains and the yield of rice. The results obtained are as follows: 1. Average number of ears per hill was increased in the treatment of nitrogen application from basal dressing to 22 days before heading and in the treatment of application distributed weekly. Number of grains was increased in the treatment of nitrogen application from 36 days to 15 days before heading. The rate of ripened grains was, lower in the treatment of nitrogen application from top-dressing to 15 days before heading than in that of non-application, was higher in the treatment of nitrogen application within 8 days before heading, and was the lowest in that of application 29 days before heading. The yield of rough rice was the highest in the treatment of nitrogen application from 29 days to 22 days before heading. The weight of 1, 000 kernels of brown rice was a little high in the treatment of application from 29 days to 8 days before heading. 2. The rate of ripened grains the yield of rough rice, the weight of 1, 000 kernels of brown rice and the rate of hulling in different treatments of leaf defoliation were remarkably decreased as the degree of leaf defoliation got larger and there were highly significant differences among treatments. There was also a recognized interaction between the time of nitrogen application and leaf defoliation. 3. In relation to the rate of ripened grains, the weight of 1. 000 kernels of brown rice and the rate of hulling in different numbers of remained leaves positioned differently and their combinations, the yield components were in order of L1(flag leaf)>L2>L3>L4 when only one leaf was remained, which indicated that the components were increased as the leaf position got higher. When two laves were remained, the rate of ripened grains, the yield of rough rice and rate of hulling were high in case of the combinations of upper positioned leaves, and the increase in the weight of 1, 000 kernels of brown rice appeared to be affected most]y by flag leaf. When three leaf blades were remained similarly the components were increased with the combination of upper positioned leaf blades. 4. In case of decreased different positioned leaf blades by treatment of leaf defoliation, there was a significant positive regression between the leaf area, the dry matter weight of leaf blades and the nitrogen contents of leaf blades, and rate of ripened grains and the yield of rough rice, but there was no constant tendency between the former components and the weight of 1. 000 kernels of brown rice. 5. The closer the time of fertilizer application to heading time, the more the rate of ripened grains and the weight of 1, 000 kernels was decreased by defoliation, and the less were the remained leaf blades, the more remarkable was the tendency. The rate of ripened grains and the weight of 1. 000 kernels was increased by the top-dressing after heading time as the number of remained leaf blades. When the number of remained leaf blades was small the yield of rough rice was increased as the time of fertilizer application was closer to heading time. 6. Discussing the productivity effects of different organs in different times of nitrogen application, the productivity effect of a leaf blade on the rate of ripened grains was higher as the time of nitrogen application got later, and in the treatment of non-fertilization the productivity effect of a leaf blade and that of culm were the same. In the productivity effect on the yield of brown rice, the effect of culm covered more than 50 percent independently on the time of nitrogen application, and the tendency was larger in the treatment of non-fertilizer. The productivity effect of culm on the weight of 1. 000 kernels of brown rice was more than 90 percent, and the productivity effect of a leaf blade was increased as the time of application got later. 7. The productivity effect of a leaf blade in different positions on the rate of ripened grains, the yield of rough rice and the weight of 1, 000 kernels of brown rice had a tendency to be increased as the time of application got later and as the position of leaf blades got higher. In the treatment of weekly application through the entire growing period, the rate of ripened grains and the yield of rough rice were affected by flag leaf and the second leaf at the same level, the but the weight of 1, 000 kernels of brown rice was affected by flag leaf with more than 60 percent of the yield of total leaves.

• 趙東三(충북대학) | 조동삼