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The world population is still increasing and food production cannot catch up, which suggests that hunger will be much more serious in the near future. Therefore, we have to make great efforts to increase production of crops, especially cereal crops. In this book we would like to focus on rice which is one of the most important cereal crops in the world and management of root system will be discussed to maximize yield.
Rice production is, as any other crops, determined by the combination of growing area and yield of unit area. Because most arable land had been already cultivated as paddy field, it is not easy to increasing rice growing area and we have to improve rice production in marginal areas including rain-fed and upland paddy under non favorite conditions. In fact rice cultivation in the world is varied with reference to ecological conditions as well as genetic background of rice grown there, but information is relatively limited. Then rice cultivation in the world will be introduced in Session 1 first of all as background for improving rice production.
We believe that managing root system is quite important to increase rice production, because it anchorages plant body and absorbs both water and nutrients which are essential for growth and development. Actually most important managing practices in crop production, for example fertilization and water control, are management to crop root system through soil. Therefore, it is necessary to improve root system management to increase yield, especially under poor soil conditions. In order to select suitable management practices, knowledge on growth and development of root system with reference to genetic and environmental factors is essential which will be discussed in Session 2. At that time we have to focus on shoot-root relationships as well, because there should be an intimate coordination between shoot and root growth. On the other hand, there should be possible relationships between structure and function of root system which is still obscure. Then physiology of root system including water and nutrient uptake will be discussed with reference to yield in the following Session 3. In Session 4, several successful trials in root system management to increase yield will be introduced. In addition, related subjects will be present in the poster session.
In these several decades, yield of rice has been increased because of both breeding new high-yielding cultivars including hybrid rice and improving cultivation methods, but it is not always still increasing at present. There is not any definite answer for breaking the yield barrier, but studying root system must give us some hints. Because there are so many unsolved problem in structure and function of root system, much more root research is necessary to improve rice production.
Shigenori Morita